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When Does a Shoe Fit?<br />
How is Chromium(VI) Formed<br />
in Leather and Leather Goods?<br />
Mould Resistance<br />
of Leathers and Intermediate Products<br />
Still Just a Dream?<br />
The Eco Shoe<br />
Newsletter<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens
2<br />
Newsletter<br />
Contents<br />
Contents<br />
Contents<br />
................................................................... 02<br />
Editorial ................................................................... 04<br />
News<br />
Radioactive Contamination<br />
of Goods from Asia? .................................................. 05<br />
Point of Shoes Well Received .................................... 06<br />
International Footwear Trade Expert ....................... 08<br />
Kai Tinschert Joins Physics Section ............................. 09<br />
Professor Klaus Mattil Turns 75 ................................. 09<br />
DSF Alumni Reunion in August ................................. 10<br />
Biotechnology<br />
The Eco Shoe – Still Just a Dream? ............................ 12<br />
Pirmasens Energy Park All Set to Go ......................... 16<br />
<strong>PFI</strong> Expands International<br />
Research Activities ...................................................... 18<br />
Research<br />
01.2011<br />
01.2011<br />
When Does a Shoe Fit? .............................................. 20
Chemistry<br />
How is Chromium(VI) Formed<br />
in Leather and Leather Goods? ................................ 24<br />
Microbiology<br />
Mould Resistance of Leathers<br />
and Intermediate Products ....................................... 28<br />
Changes to ASTM E2149 /<br />
Challenge Test Method ............................................. 30<br />
Physics<br />
Shoe Accessory with Core Strength .......................... 36<br />
Masthead<br />
Publisher: <strong>PFI</strong> Test and Research Institute Pirmasens<br />
Prüf- und Forschungsinstitut Pirmasens e. V.<br />
Member of <strong>PFI</strong> <strong>Group</strong><br />
Director of Institute: Dr. Gerhard Nickolaus<br />
Address: Marie-Curie-Straße 19<br />
66953 Pirmasens / Germany<br />
Phone: +49 6331 2490 0<br />
Fax: +49 6331 2490 60<br />
E-Mail: info@pfi-germany.de<br />
Internet: www.pfi-germany.de<br />
Editor: Elisabeth Rouiller<br />
Translation: Tony Rackstraw<br />
Design Concept and Layout:<br />
Konzept fünf - Agentur für Werbung und Design<br />
Internet: www.konzept-fuenf.de<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Pictures:<br />
Fotolia (p. 5),<br />
August Herzog Maschinenfabrik GmbH & Co KG (p. 38),<br />
<strong>PFI</strong>, ISC<br />
Reprint – extracts included – only with authorisation<br />
of the <strong>PFI</strong>.<br />
The online-version of the <strong>PFI</strong>-Newsletter is available<br />
under www.pfi-group.org/newsletter.html<br />
3
4<br />
Editorial<br />
Newsletter<br />
Dear Readers,<br />
The latest issue of the <strong>PFI</strong> Newsletter has now been<br />
published. We trust that it will again provide you<br />
with a wealth of valuable and interesting information<br />
about the research activities and services offered by<br />
<strong>PFI</strong>. Like any other dynamic organisation, <strong>PFI</strong> is in a<br />
state of constant flux; traditional areas of activity are<br />
contracting, new areas are expanding.<br />
EDIToRIAL<br />
Thus our Biotechnology Department is currently moving<br />
ahead under full steam, undoubtedly having received<br />
an additional boost from recent events in Japan.<br />
Alternative approaches to power generation, decentralised<br />
solutions for conservation of fossil resources<br />
and reduction of effective CO emissions, as well as the<br />
2<br />
synthesis of raw materials and plastics from renewable<br />
resources are all much in demand. We have our eye on<br />
the ball. Of course, we cannot claim to be able to solve<br />
the fundamental problems of energy generation, but<br />
we can make an important contribution to the mosaic<br />
of future energy supplies. For our original area of core<br />
competence, the footwear industry, attractive possibilities<br />
resulting from use of biodegradable polymers<br />
produced from renewable resources can open up new<br />
markets.<br />
We greatly appreciate your interest in current developments<br />
and projects undertaken at <strong>PFI</strong>. Do not hesitate<br />
to contact us if you have any questions or suggestions.<br />
Contact details of our department heads will be found<br />
in this publication. And, of course, I am also glad to be<br />
of assistance wherever I can.<br />
Yours Dr. Gerhard Nickolaus<br />
<strong>PFI</strong> <strong>Group</strong>
NEWS<br />
The accident at the Fukushima nuclear power station<br />
in Japan and the subsequent escape of radioactive<br />
nuclides, which have been and still are at the centre<br />
of world-wide attention, are a cause for concern for<br />
companies which manufacture goods in the Far East<br />
or import goods produced in factories located in that<br />
region. After all, those persons who place products on<br />
the market are ultimately responsible for them. The<br />
question arises whether the goods are radioactively<br />
contaminated, and if so to what extent. It is also necessary<br />
to establish whether, and if so which, safety<br />
measures are appropriate, for example whether tests<br />
for radioactive contamination prior to shipment are<br />
advisable.<br />
In the estimation of the German Federal Institute for<br />
Risk Assessment and the Federal Ministry of the Environment,<br />
Nature Conservation, and Reactor Safety,<br />
goods from other Asian countries (such as China or<br />
India) were not subject to any specific threat of radioactive<br />
contamination at the time of going to press.<br />
Hence footwear manufacturers with production facilities<br />
in Asian countries other than Japan need not expect<br />
any such risks and therefore need not adopt any<br />
additional precautionary measures. It is difficult to assess<br />
the situation regarding goods from Japan itself.<br />
Shipping companies and airlines have adopted appropriate<br />
measures and have avoided or continue to<br />
avoid the area.<br />
Goods entering Germany from Japan are subjected<br />
to random testing for radioactivity by the customs<br />
authorities. EU-wide fast-track legislation has been<br />
enacted and direct safety precautions introduced for<br />
foods imported from Japan, which pose a significantly<br />
greater risk of radioactive contamination and an associated<br />
health hazard for the consumer.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Possible Consequences of the Nuclear Accident at Fukushima<br />
Radioactive Contamination<br />
of Goods from Asia?<br />
A direct threat of radioactive contamination in and for<br />
Germany is ruled out by experts. However, the situation<br />
regarding consumer goods may change at short notice<br />
in view of the dynamic course of developments.<br />
Current information about the situation both in general<br />
and with regard to the consequences, particularly<br />
in Germany, can be found at: http://www.bfr.bund.de<br />
or http://www.bmu.de.<br />
Further information:<br />
Dipl.-Biologin Michaela Würtz<br />
Phone: +49 6331 2490 550,<br />
E-Mail: michaela.wuertz@pfi-germany.de<br />
5
6<br />
Newsletter<br />
The third Point of Shoes – International Fair for Fashion,<br />
Materials and Production (PoS), which took place<br />
at Pirmasens on 19 and 20 April, got off to a resounding<br />
start. Although the event took place during the Easter<br />
holiday period, almost 450 visitors were present on<br />
both days of the show and displayed an avid interest<br />
in the offerings of the 77 exhibitors. “Almost all the<br />
German footwear manufacturers were represented,<br />
meaning that we have attained the important goal of<br />
again attracting the domestic companies en bloc to<br />
Pirmasens”, summarised PoS organiser Uwe Thamm.<br />
Shoe machines were a special feature of this PoS; 15<br />
companies showcased their innovations. This technology<br />
platform will be featured every two years. And<br />
the PoS lecture programme, devoted this time to the<br />
Keynote Topic of sustainability, generated keen interest.<br />
“According to the latest available statistics dating from<br />
2009, the German footwear industry comprises 45 companies<br />
with more than 50 employees – and the registration<br />
data clearly show that the PoS attendees represent<br />
the entire domestic footwear sector”, says Uwe Thamm.<br />
“Companies which for many years have only travelled<br />
to Bologna are now coming back to Pirmasens. And<br />
most importantly: The decision makers are coming.”<br />
NEWS<br />
High Level of Visitor Acceptance, Top-Quality Lectures<br />
Point of Shoes<br />
Well Received<br />
“We were surprised by the quality of the discussions<br />
and were able to establish new contacts”, said<br />
Christopher Thornhill of Molina & Bianchi.<br />
Confirmation comes from the exhibitors: “The delegations<br />
coming to the show are generally made up of just<br />
two or three people, but they are very knowledgeable<br />
experts who are authorised to make decisions. Window<br />
shoppers and gawkers, on the lookout for cookies<br />
and ball-point pens, don’t come here”, according<br />
to Sam Neuer of the Zweibrücken-based company Innovatec.<br />
“We were surprised by the quality of the discussions<br />
and were able to establish new contacts; our<br />
expectations were thus surpassed”, said Christopher<br />
Thornhill of Molina & Bianchi. A hint of reservation<br />
was nevertheless expressed by some of the exhibitors:<br />
“It could all be somewhat more international.”
NEWS<br />
“We shall gladly pursue that point”, was the response<br />
of Uwe Thamm. “Now that we have attained our<br />
first objective, that of bringing the German footwear<br />
manufacturers back to Pirmasens, and now that Italian,<br />
Spanish, Portuguese, Czech, and even Chinese<br />
companies number among the exhibitors at PoS, we<br />
shall initially concentrate on attracting visitors from<br />
neighbouring countries. However, we should not expect<br />
miracles: Attracting international visitors will<br />
take time. But we are working on it.”<br />
The concluding discussion, chaired by Petra Salewski,<br />
Editor-in-Chief of the trade journals Schuhkurier and<br />
Steptechnik, has meanwhile become a traditional<br />
feature of PoS. The conclusion to be drawn from this<br />
discussion, attended mainly by exhibitors, was that no<br />
consensus can be reached in the matter of dates: The<br />
proponents of an earlier date and of a later date split<br />
into two fairly irreconcilable groups. And then there<br />
are additional constraints imposed by space allocation<br />
in the exhibition halls and public holidays. “The next<br />
PoS will take place on 3 and 4 November 2011, as was<br />
decided on the basis of exhibitor and visitor questionnaires<br />
in September 2010. In November we shall know<br />
the key data for 2012 and again strive to find ‘ideal’<br />
dates”, explained Thamm.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
PoS organiser and ISC Head<br />
Uwe Thamm gave a positive assessment<br />
of the April Point of Shoes<br />
It has already been decided that the November PoS<br />
Fair will close at 2 p.m. on the second day. The second<br />
day of the event is still necessary, even if there are not<br />
so many visitors as on the first day: After all, about one<br />
third of the attendees only came on the second day.<br />
It has also been decided to move the open discussion<br />
session with exhibitors and visitors forward to 5 p.m.<br />
on the first day.<br />
The New Keynote Topic for the November PoS will be<br />
“Ten Years into the Future. Global Scenarios for the<br />
European Footwear Industry 2021”.<br />
“And another matter of great concern to us is the provision<br />
of a WLAN connection in the exhibition halls”,<br />
was Uwe Thamm’s final observation. “We sincerely<br />
hope that the City of Pirmasens can arrange for its installation<br />
between now and the next PoS.”<br />
Contact<br />
Point of Shoes contact partner at ISC is Steffen Korf.<br />
E-Mail: steffen.korf@isc-germany.com<br />
Phone: +49 (0)6331 145334-17<br />
Fax: +49 (0)6331 145334-30<br />
Further information can be found at<br />
www.point-of-shoes.com.<br />
PoS is organised by:<br />
International Shoe Competence Center<br />
Pirmasens gGmbH<br />
Director: Dipl.-Ing. (FH) Uwe Thamm<br />
Marie-Curie-Straße 20<br />
66953 Pirmasens / Germany<br />
Phone: +49 6331 145334-0<br />
E-Mail: info@isc-germany.com<br />
Internet: www.isc-germany.com<br />
7
8<br />
Newsletter<br />
The Chamber of Industry and Commerce (Industrieund<br />
Handelskammer, IHK) and the International<br />
Shoe Competence Center Pirmasens have together<br />
launched a new certification course: Qualification as<br />
“International Footwear Trade Expert” meets a real<br />
demand and can be completed over a period of nine<br />
weekends.<br />
The “International Footwear Trade Expert” course is<br />
designed for employees of footwear manufacturers,<br />
suppliers to the footwear industry, and footwear dealers<br />
without a background in footwear. The participants<br />
acquire the general and footwear-specific know-how<br />
necessary for a job in the international shoe trade.<br />
72 Hours Packed Full of Challenges<br />
The new course can be completed on nine Saturdays<br />
by persons in regular employment and concludes with<br />
a certification exam. The participants will spend six of<br />
the nine Saturdays at ISC Germany, where they can<br />
benefit from the facilities of the ISC “training factory”,<br />
and three at the Chamber of Industry and Commerce<br />
in Pirmasens. The course covers the following topics:<br />
International trade and customs procedures<br />
Logistics<br />
Quality demands placed on footwear<br />
Certificates of origin<br />
Makes, production methods<br />
Footwear terminology and footwear English<br />
Business fundamentals<br />
Complaints management<br />
Hazardous substances<br />
NEWS<br />
New IHK / ISC Certification Course<br />
International<br />
Footwear Trade Expert<br />
Future footwear trade experts will be able to begin<br />
their training at ISC Germany in the course of 2011<br />
“Today’s footwear industry is totally internationalised,<br />
which also means that the procurement chains<br />
are becoming ever longer and more complex”, according<br />
to Uwe Thamm, Head of ISC Germany. “The new<br />
certification course fills a training gap by providing,<br />
in compact and highly practical manner, the specialist<br />
knowledge necessary to confidently cope with all<br />
aspects of procurement.”<br />
The first footwear trade experts can start the course in<br />
the fourth quarter of 2011 and receive their certificate<br />
in the first quarter of 2012. The course will cost approximately<br />
1700 Euro.<br />
Contact:<br />
Dipl.-Ing. Uwe Thamm<br />
International Shoe Competence<br />
Center Germany gGmbH<br />
Marie-Curie-Straße 20<br />
66953 Pirmasens / Germany<br />
Phone: +49 6331 14 53 34 0<br />
E-Mail: info@isc-germany.com´<br />
Internet: www.isc-germany.com
NEWS<br />
Welcome to the Team<br />
Kai Tinschert<br />
Joins Physics Section<br />
Kai Tinschert completed his studies for a Diplom-Ingenieur<br />
degree in textile engineering specialising in<br />
surface engineering at the Pirmasens Campus of the<br />
Kaiserslautern University of Applied Sciences in August<br />
2009. He went on to gain practical experience at<br />
a leading manufacturer of special elastic fabrics for<br />
medical products.<br />
In January 2011 he joined the Physical Materials Testing<br />
and Research team at <strong>PFI</strong>. After first familiarising himself<br />
with all areas of activity and procedures, his main<br />
field of work will be in research and testing of textiles.<br />
Congratulations<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Professor Klaus Mattil Turns 75<br />
A thoroughbred shoemaker, exceptionally gifted engineer<br />
and teacher, ever-helpful colleague, and dyedin-the-wool<br />
native of the Palatinate is how we can<br />
best describe Professor Klaus Mattil. over the 30-year<br />
period from 1969 to 1999 he headed the Technical Department<br />
of <strong>PFI</strong>. on 3 May 2011 he celebrated his 75th<br />
birthday. The entire staff at <strong>PFI</strong> joins together in congratulating<br />
him on this occasion.<br />
This living idea generator Klaus Mattil has instigated<br />
innumerable projects and developments, and he continues<br />
to work with an enormous level of commitment<br />
to this day – far beyond the usual age of retirement.<br />
Particularly impressive is the energy he invested in his<br />
pioneering and trend-setting activities at <strong>PFI</strong>, and subsequently<br />
as <strong>PFI</strong> consultant and professor at Kaiserslautern<br />
University of Applied Sciences, where he continues<br />
to communicate his profound knowledge to students.<br />
“My wish for the footwear world is that Professor Mattil<br />
will long continue to place his knowledge and his energy<br />
in its service”, is how <strong>PFI</strong> Director Dr. Gerhard Nickolaus<br />
expressed his sentiments. “Congratulations, Professor<br />
Mattil, and long may you carry on the good work!”<br />
9
10<br />
Newsletter<br />
German College of Footwear Design and Technology<br />
DSF Alumni Reunion<br />
in August<br />
Just over two years ago, students and members of the<br />
teaching staff of the German College of Footwear Design<br />
and Technology (Deutsche Schuhfachschule, DSF)<br />
undertook a study trip to Portugal to visit a number of<br />
footwear factories. The trip was, of course, interesting<br />
and informative. However, among the highlights<br />
of the excursion, top place went to the discussions<br />
held with DSF alumni who now live and work in Portugal.<br />
In fact, these meetings were so interesting that<br />
the wish arose to pursue exchange of information<br />
and experience with other DSF alumni, wherever they<br />
might be in the world. Thus the idea of organising an<br />
inter-year reunion for DSF graduates was born.<br />
open-ended clicking presses<br />
at the Footwear College<br />
in the mid-1950s<br />
NEWS<br />
A date has now been set for this meeting: Alumni of all<br />
entry years of the German College of Footwear Design<br />
and Technology as well as friends and sponsors of the<br />
college are cordially invited to the grand reunion starting<br />
at 5 p.m. on 20 August 2011. The meeting points<br />
are located on the premises of the German College of<br />
Footwear Design and Technology at the International<br />
Shoe Competence Center (ISC Germany, Marie-Curie-<br />
Str. 20, 66953 Pirmasens) and at the Pirmasens Festival<br />
Hall from 7 p.m. onwards.<br />
The new premises of the Footwear College at ISC can<br />
be viewed during a champagne reception starting at<br />
5 p.m. A photo exhibition will tell the history of the<br />
Footwear College from its foundation in 1927 right<br />
up to the present day. The pictures illustrate everyday<br />
aspects and highlights in the life of the Footwear College<br />
and also track changes in the facilities and equipment<br />
at the school in the course of time. Of course,<br />
class photos of all the graduation years are an absolutely<br />
essential component of any such exhibition. Numerous<br />
exhibits will also relate individual stories from<br />
the long history of our College. All participants will<br />
receive a brochure showing highlights of this exhibition.<br />
Anybody who has additional photos or materials<br />
is kindly asked to make these documents available for<br />
20 August.
The response of alumni has been so overwhelming<br />
that the main celebration originally planned to take<br />
place on the premises of ISC had to be relocated to the<br />
Pirmasens Festival Hall. Graduates are eagerly anticipating<br />
this evening and meeting and conversing with<br />
former students and teachers. In order to facilitate<br />
planning of the event, all interested persons should<br />
register as soon as possible and inform the Footwear<br />
College of their contact details by e-mail or letter. A<br />
registration form can be found at www.bbspirmasens.<br />
de. Further information will be distributed prior to the<br />
meeting on 20 August. And do not forget to inform all<br />
alumni with whom you have kept in touch!<br />
Contact<br />
Deutsche Schuhfachschule<br />
at BBS Pirmasens<br />
Adlerstraße 31<br />
66955 Pirmasens / Germany<br />
Phone: +49 (0)6331-24010<br />
Fax: +49 (0)6331-240120<br />
Internet: www.bbspirmasens.de<br />
E-Mail: schuhfachschule@freenet.de<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Modern clicking presses and cutting tables<br />
in the well-equipped machine shop of ISC,<br />
the new home of the German College of<br />
Footwear Design and Technology<br />
11
12<br />
Newsletter BIoTECHNoLoGY<br />
Joint Project of <strong>PFI</strong> and Kaiserslautern University of Applied Sciences<br />
The Eco Shoe – Still<br />
Just a Dream?<br />
Just imagine there were such a thing, a 100 percent<br />
eco shoe … no recycling problems, great consumer<br />
acceptance, tomorrow’s ultimate product. Today’s<br />
reality looks very different: up to the present shoes<br />
remain a disposal nightmare. The situation is untenable<br />
and that is why <strong>PFI</strong>’s Biotechnology Department<br />
and Kaiserslautern University of Applied Sciences are<br />
planning a joint project with the principal goal of developing<br />
a shoe that can be bio-recycled.<br />
Two facts are indisputable: Consumer demand for ecofriendly<br />
products is steadily increasing and regulatory<br />
demands are becoming ever more stringent. For this<br />
reason <strong>PFI</strong> has set up a research project bearing the<br />
name “Development of Shoe Production Based on Renewable<br />
and Fermentable Materials”. The declared<br />
aim is 100 % bio-recycling of footwear at the end of<br />
its product life cycle together with all waste from the<br />
production process, with complete utilisation of all the<br />
material and energetic resources present in the materials.<br />
Another aim of the project is to promote sales of<br />
ecologically valuable footwear in Germany and thus<br />
to open up a new market for SMEs belonging to the<br />
footwear industry and its suppliers.<br />
Greater Environmental<br />
Consciousness<br />
More and more enquiries about eco-friendly products<br />
are reaching footwear manufacturers and <strong>PFI</strong>; a sure<br />
indication that the ecological awareness of consumers<br />
is on the increase. Topics such as sustainable material<br />
and product development, energy efficiency,<br />
and conservation of resources are of interest to everincreasing<br />
numbers of consumers or to that steadily<br />
growing group of person who consciously strive<br />
to pursue an eco-friendly lifestyle. Whether or not a<br />
product has been sustainably developed and produced<br />
clearly influences purchasing decisions made by these<br />
consumers. At the same time, manufacturing industry<br />
has understood – not least because of increasing material<br />
and energy prices – that sustainable operation<br />
and effective, and where possible waste-free, utilisation<br />
of resources are worthwhile. While earth-muffiny<br />
niche products have long been available, the footwear<br />
industry has now begun large scale use of materials<br />
which fulfil two principal purposes: On the one hand,<br />
they yield products of excellent ecological value manufactured<br />
by sustainable production processes wherever<br />
possible; on the other, they permit recycling of as<br />
many as possible of the raw materials and components<br />
used in production which are still present at the end<br />
of the product life cycle. In a parallel development, increasingly<br />
stringent regulations are compelling companies<br />
to recycle ever greater proportions of their<br />
waste and to design their products in compliance with<br />
ecological standards.
THE ECo SHoE - STILL JUST A DREAM?<br />
Footwear Problems:<br />
Material Diversity and Composites<br />
The footwear industry faces the particularly challenging<br />
task of offering ecologically valuable products in<br />
combination with efficient utilisation of resources, because<br />
a shoe represents a combination of widely differing<br />
materials. Furthermore, only limited use is presently<br />
made of ecologically valuable materials.<br />
An automated separation unit for all materials would<br />
give rise to certain ecological burdens. It would also<br />
significantly increase disposal costs. Unlike in the electrical<br />
and electronics industry, for example, which<br />
processes noble metals whose recycling is definitely<br />
worthwhile, footwear does not contain any high-price<br />
materials. It is therefore questionable whether such<br />
a sorting unit would be really worthwhile. If such a<br />
separation unit for shoes were to operate profitably,<br />
it could only do so by processing comparatively large<br />
amounts of waste. That would create disposal problems,<br />
above all for SMEs. In addition, only thermoplastics<br />
and metals would be to some degree recyclable,<br />
all the other waste could only be utilised thermally. It<br />
would also be necessary to demonstrate that the energy<br />
generated exceeds the amount of energy invested<br />
in the separation process.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Project partner of <strong>PFI</strong> is the Western Palatinate Institute<br />
of Plastics Engineering on the Pirmasens Campus<br />
of Kaiserslautern University of Applied Sciences<br />
Conventional approaches to the recycling of industrial<br />
wastes from footwear production are based either on<br />
the principle of reutilising certain classes of substances,<br />
which can be admixed to a certain extent with new<br />
material, or on the principle of thermal utilisation.<br />
However, the (largely fossil) material resources would<br />
be lost on combustion. At the same time, residues<br />
proving difficult to dispose of, such as slag or spent<br />
combustion plant filters, would also arise.<br />
13
14<br />
Newsletter<br />
Joint Project of <strong>PFI</strong> and Kaiserslautern University of Applied Sciences<br />
The Eco Shoe – Still<br />
Just a Dream?<br />
New hydrothermal and enzymatic digestion plant<br />
in the <strong>PFI</strong> engineering lab<br />
BIoTECHNoLoGY<br />
New Materials<br />
and Recycling Methods<br />
The joint project of <strong>PFI</strong> Biotechnology Department and<br />
Kaiserslautern University of Applied Sciences envisages<br />
that development and selection of special materials<br />
(cellulose, starch blends, as well as other biopolymers)<br />
and processing methods will enable all the materials<br />
used in footwear together with the waste generated<br />
during production first to be comminuted and<br />
then merged together. Hydrothermal and enzymatic<br />
digestion cleave the substances into smaller building<br />
blocks and the resulting monomers or oligomers can<br />
be transformed by microorganisms into new starting<br />
materials such as biopolymers in a fermentation process.<br />
Any remaining components that cannot be put to<br />
material use are converted into biomethane (methane<br />
produced from biomass). The objective is optimum<br />
utilisation of all the energy and material resources<br />
present in the footwear materials. Headed by Professor<br />
Dr.-Ing. Jens Schuster, the Western Palatinate Institute<br />
of Plastics Engineering (Institut für Kunststofftechnik<br />
Westpfalz, IKW) on the Pirmasens Campus of Kaiserslautern<br />
University of Applied Sciences serves as second<br />
research establishment for the polymeric components<br />
of footwear. In the course of the project it is intended<br />
to develop an outsole material which has the rubberyelastic<br />
properties of a conventional sole material while<br />
also fulfilling all biodegradability criteria.
THE ECo SHoE - STILL JUST A DREAM?<br />
Material Database<br />
Depending upon their field of use in footwear, the<br />
newly developed materials are tested for their suitability<br />
for footwear manufacture in the Physical Materials<br />
Testing Department of <strong>PFI</strong>. The neighbouring<br />
ISC subsequently produces sample shoes in close cooperation<br />
with shoe manufacturers and suppliers to the<br />
footwear industry. The data collected in the course of<br />
the research project, concerning, for example, the fermentability<br />
or the mechanical properties of the biodegradable<br />
materials, are to be compiled in a database<br />
and subsequently published. This information provides<br />
footwear manufacturers with an opportunity to<br />
increasingly attune their products to ecological needs<br />
and future regulatory requirements. The knowledge<br />
gained, together with the database for all materials<br />
used in footwear production, should open the door<br />
to ecologically appropriate footwear production by<br />
making components such as linings, upper materials,<br />
or adhesives biodegradable. The results of outsole development<br />
illustrate the huge development potential<br />
of biodegradable elastic polymers. They also provide<br />
a basis for further projects focussing on the development<br />
of ecologically valuable hard-wearing footwear.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
<strong>PFI</strong> Combines Footwear Competence<br />
with Biotechnology<br />
With this project <strong>PFI</strong> intends to establish a link between<br />
the original core competence of the organisation, i.e.<br />
footwear engineering, and the relatively young <strong>PFI</strong><br />
Biotechnology Department, gain further experience<br />
in the area of biopolymers, and demonstrate practical<br />
applications of developments ensuing from the on-going<br />
project concerning production of PHB undertaken<br />
together with the Johannes Gutenberg University at<br />
Mainz (Report: Newsletter 1.2010 – pp. 7 et seqq.).<br />
The research project has already received a favourable<br />
response. A 2011 project starting date is envisaged.<br />
Further information:<br />
Dipl.-Ing. (FH) Christian Schadewell<br />
Phone: +49 6331 2490 - 843<br />
E-Mail: christian.schadewell@pfi-germany.de<br />
15
16<br />
Newsletter<br />
Pirmasens Energy Park All Set to Go<br />
Purchase of a site in the Winzeln industrial zone of Pirmasens<br />
by <strong>PFI</strong> has set the scene for practice-oriented<br />
international research into material and energetic utilisation<br />
of biomass.<br />
The Biotechnology Department came into existence<br />
when <strong>PFI</strong> moved to the Husterhöhe area of Pirmasens<br />
in 2003. From the very beginning, research focussed<br />
on the fast and efficient digestion of biomass. And<br />
work was by no means limited to production of biogas<br />
as an energy source; the goal was also to produce<br />
high-value fermentation products with the aid of biotechnological<br />
processes. Thus the production of xylose<br />
from straw and its microbiological transformation into<br />
xylitol was initially optimised. Other target products<br />
followed, such as lactic acid and polyhydroxybutyric<br />
acid (PHB) which can be used for biopolymer production.<br />
In the course of time it became apparent that<br />
economic production of energy and raw materials<br />
from biomass is possible only if the necessary production<br />
processes performed in decentralised facilities are<br />
properly matched to one another, thus resulting in<br />
synergy effects. It is also necessary to intensify the use<br />
of lignocellulose-containing residual biomass such as<br />
straw as co-substrate in order to conserve agricultural<br />
land for food production.<br />
BIoTECHNoLoGY<br />
<strong>PFI</strong> Invests in Pilot Plant<br />
for Biomass Fermentation<br />
The scientific and technical basis for practical implementation<br />
of the idea has been established in various<br />
individual projects. Thus thermal pressure hydrolysis<br />
for activated sludge was tested on an industrial scale<br />
at the Blümelstal sewage plant in Pirmasens and was<br />
found to increase biogas production by up to 25 percent.<br />
“Process-controlled enzymatic hydrolysis” (PEH)<br />
is used to accelerate the degradation of cellulose in an<br />
agricultural biogas plant at Wallhalben near Pirmasens<br />
in order to double the throughput of the plant without<br />
detrimental effects on the process biology. Other<br />
experimental units for straw digestion were also tested<br />
in the <strong>PFI</strong> engineering laboratory. In spite of the success<br />
of individual projects, it has so far proved impossible<br />
to integrate all the technical developments accomplished<br />
by the Biotechnology Department into a single<br />
practically functioning plant in order to scrutinise the<br />
expected synergy effects. Such scrutiny should become<br />
possible and a basis created for further research<br />
projects and technical developments on construction<br />
of a demonstration plant.<br />
The projected fermentation plant is intended to process<br />
5,000 t of sugar beet, 3,000 t of maize silage, 1,000<br />
t of straw, and 500 t each of whole-crop cereal silage<br />
(WCCS) and grass silage per year. Annual production<br />
of 100 t of xylitol and 400 t PHB is the set goal. In addition,<br />
the plant will generate 500 kW of electrical energy<br />
to be fed into the grid and 500 kW of thermal<br />
energy for the provision of process heat. This corresponds<br />
to an efficiency of over 80 percent in terms of<br />
the biomass consumed. On average only about 40 to<br />
60 percent of the biomass used is currently converted<br />
into electrical and thermal energy.
<strong>PFI</strong> INVESTS IN PILoT PLANT<br />
The following plant components newly developed by<br />
<strong>PFI</strong> and its partner organisations will be installed to<br />
implement the innovative concept:<br />
Lagoons holding liquid sugar beet silage for<br />
automatic charging of the fermenters<br />
Digestion unit for hydrothermal degradation<br />
of lignocelluloses<br />
PEH reactor for mixing and liquefying the richly<br />
structured biomass and acceleration of cellulose<br />
degradation<br />
Fixed-bed fermenter for lactic acid production<br />
and acceleration of the biogas process<br />
Evaporation unit for concentration of the hydro-<br />
lysis and fermentation digestates<br />
Cogeneration unit for energetic utilisation of<br />
hydrogen-rich biogas<br />
High-temperature heat pump for generation<br />
of process heat for the evaporation process<br />
Digestate processing plant for fixation of<br />
ammoniacal nitrogen in the fermentation residue<br />
A central building at the demonstration plant is to<br />
house a training room and a control centre from which<br />
the various processes can be controlled and optimised<br />
under the supervision of engineers and scientists.<br />
Practical information and training sessions can also be<br />
offered. The premises will also accommodate members<br />
of various international research establishments<br />
working as teams on multi-year research projects. In<br />
particular, close scientific collaboration in the area of<br />
biomass utilisation is planned between Rhineland-<br />
Palatinate and Lorraine. Being so close to France, the<br />
projected demonstration plant should also help intensify<br />
collaboration between farmers and companies<br />
from the two regions. Supporting roles are envisaged<br />
for agricultural associations and the chambers of industry<br />
and commerce. Pro-rata funding for the projected<br />
demonstration plant is expected from the Life+<br />
Programme of the European Union. Applications for<br />
funding of cross-border cooperation between Rhineland-Palatinate<br />
and Lorraine are to be submitted via<br />
the Interreg IV programme.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Now that the plot has been purchased, <strong>PFI</strong> can proceed<br />
with permit planning. This will be undertaken in close<br />
consultation with the City of Pirmasens and Bioenergie<br />
Pirmasens, a subsidiary of the Pirmasens municipal<br />
utility company. In total, three plants are planned for<br />
the Pirmasens Energy Park: a steam gasification unit<br />
for wood, a methanisation plant for biogenic municipal<br />
waste, and the above fermentation plant for agricultural<br />
biomass. Construction of the last-mentioned<br />
demonstration plant is scheduled to begin in mid-<br />
2012.<br />
Silo for maize<br />
and grass silage<br />
Straw storage<br />
Fermentation technology<br />
and product preparation<br />
Storage tank<br />
Straw digestion<br />
plant<br />
Projected <strong>PFI</strong> demonstration plant at the<br />
Pirmasens-Winzeln energy park<br />
Further information:<br />
Dipl.-Ing. (FH) Benjamin Pacan<br />
Phone: +49 6331 2490 - 840<br />
E-Mail: benjamin.pacan@pfi-biotechnology.de<br />
Control center and<br />
training room<br />
PEH reactor<br />
CHP container<br />
Lagoon for liquid<br />
sugar beet silage<br />
Methane<br />
digester<br />
Fixed-bed<br />
fermenter<br />
17
18<br />
Newsletter<br />
In past years <strong>PFI</strong> has repeatedly initiated EU projects<br />
related to its core competence of footwear engineering.<br />
It is no secret that the level of funding in this area<br />
has meanwhile started to fall owing to the transfer of<br />
footwear production to Asia. The alternative is to acquire<br />
EU funding for <strong>PFI</strong>’s new key research activities<br />
biotechnology and regenerative energies. To achieve<br />
this goal the Engineering and Biotechnology Departments<br />
will be collaborating even more closely.<br />
Owing to the expected participation of more than six<br />
countries and bureaucratic hurdles in the application<br />
phase, many of the funding possibilities set out in the<br />
7th EU Framework Research Programme require a<br />
high commitment of human resources. The low success<br />
rate, which often lies below 15 percent, also poses<br />
a considerable financial risk for the applicant. In order<br />
to minimise expenditure of effort and risks, submission<br />
of applications for transnational projects involving<br />
only two to three European partners was first considered.<br />
In response to the current call for proposals,<br />
a CORNET project on the topic «Upgrading of Waste<br />
Heat to Process Heat for Different Industries» (for<br />
short «From Waste Heat to Process Heat») was submitted<br />
by <strong>PFI</strong> together with Papiertechnische Stiftung of<br />
Munich (coordinator), University College of West Flanders,<br />
Ghent University, Université de Liège, and the<br />
Flemish User <strong>Group</strong>.<br />
BIoTECHNoLoGY<br />
New EU Project Proposals Submitted<br />
<strong>PFI</strong> Expands International<br />
Research Activities<br />
CORNET stands for Collective Research Networking, i.e.<br />
networking of national and regional programmes of<br />
community research in Europe. The ERA-NET CORNET<br />
coordinated by the German Federation of Industrial<br />
Research Associations involves participation of 21 ministries<br />
and lead partners from 17 countries and regions<br />
of Europe. The objective is to intensify European coordination<br />
between national and regional programmes<br />
of community research. CORNET organises two rounds<br />
of calls for proposals per year for jointly funded community<br />
research projects.<br />
The high-temperature heat pump to be developed in<br />
this project is an important technical aid for concentration<br />
of sugar solutions by two-stage vacuum evaporators<br />
prior to fermentation. In addition, process water<br />
can also be recovered for straw digestion. Improved<br />
utilisation of waste heat from the cogeneration unit<br />
permits use of more straw as substrate for the fermentation<br />
plant. After determination of the thermal<br />
energy required for the various sub-processes of the<br />
innovative biomass processing plants, the <strong>PFI</strong> Engineering<br />
Department will develop an intelligent control<br />
system for heat management in connection with<br />
the high temperature heat pump. The Biotechnology<br />
Department will undertake practical tests and develop<br />
optimisation proposals. The SMEs participating in the<br />
project (for example, a biogas plant operator) should<br />
be placed in a position to better utilise the waste heat<br />
from cogeneration plants. Furthermore, economic aspects<br />
are to be considered and design parameters determined<br />
for the use of high temperature heat pumps.
NEW EU-PRoJECT PRoPoSALS SUBMITTED<br />
In view of the European Union’s aims of raising the<br />
contribution of renewable energy sources to power<br />
generation to over 20 percent by 2020 and of doubling<br />
the current eight to ten percent market share of<br />
bio-based products by 2020, <strong>PFI</strong> is expecting a significant<br />
increase in research funding in these areas in the<br />
coming years. The nuclear catastrophe at Fukushima<br />
and increasing oil prices will certainly further boost<br />
this trend.<br />
A planned Interreg IV project should serve as an introduction<br />
to transnational collaboration in the increased<br />
use of biomass. <strong>Here</strong> <strong>PFI</strong> wishes to cooperate with the<br />
Lorca Agricultural Cooperative, the Lorraine Farmers’<br />
Association, and the “Ecole Nationale Supérieure<br />
d'Agronomie” as well as SMEs in Rhineland-Palatinate<br />
and Lorraine. The planned project encompasses the<br />
following tasks:<br />
Advice on plant cultivation, harvesting, and<br />
transportation logistics<br />
Cultivation, supply, and preservation of energy crops<br />
Construction, operation, and development of<br />
digestion and fermentation plants<br />
Optimisation of the fertilising action of digestion<br />
residues<br />
Waste Biomass<br />
Digester<br />
Xylitol<br />
as a Sugar Substitute<br />
Biogas<br />
Waste Heat<br />
Residual Biomass<br />
Electrical<br />
Energy<br />
Combined Heat<br />
and Power Plant<br />
Engine Cooling System<br />
High-temperature<br />
Heat Pump<br />
Fermentation<br />
Plant<br />
Biotechnological<br />
Conversion<br />
Projected use of a high-temperature heat pump in a biomass processing plant<br />
Organisation of information events and seminars<br />
Exhaust Heat<br />
Process Heat<br />
Waste Heat<br />
Lignocellulosic<br />
Biomass<br />
TPH<br />
Vacuum<br />
Evaporator<br />
Hydrolyzate Concentrate<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Biopolymers as Polyhydroxyalkanoates<br />
(PHA) from Glucose and organic Acids<br />
The planned transnational research projects should<br />
provide a basis for further European research activities.<br />
In the future, <strong>PFI</strong> plans to submit several project<br />
proposals yearly in the 7th EU Framework Research<br />
Programme. Staff members of various European research<br />
institutions will spend time working at <strong>PFI</strong> in<br />
order to establish an appropriate network. A European<br />
research and development manager will be appointed<br />
at <strong>PFI</strong> to coordinate these activities. Small and<br />
medium-sized enterprises are invited to participate.<br />
<strong>PFI</strong> will be glad to help with preparation of the necessary<br />
project documentation.<br />
Further information:<br />
Dipl.-Ing. (FH) Benjamin Pacan<br />
Phone: +49 6331 2490 - 840<br />
E-Mail: benjamin.pacan@pfi-biotechnology.de<br />
19
20<br />
Newsletter<br />
Innovative Method for Fitting Shoes<br />
When Does a Shoe Fit?<br />
Fortunately, proper fit has returned to the focus of attention<br />
of footwear manufacturers, retailers, and customers.<br />
This interest was rekindled by the results of a<br />
Germany-wide foot measuring campaign undertaken<br />
in an AiF research project (the results are to be found<br />
in a German-language publication entitled “The Foot<br />
Report” which can be ordered from the address given<br />
at the end of this article). AiF is the German Association<br />
of Industrial Research organisations. This study<br />
showed that properly fitting shoes are hard to find<br />
by conventional methods of shoe selection. A further<br />
AiF research project was therefore launched in order<br />
to develop an innovative and economically practicable<br />
shoe selection method permitting choice of better<br />
fitting shoes.<br />
Cumulative frequency in %<br />
Fig. 1:<br />
Level of provision<br />
of different widths<br />
for women<br />
Availability<br />
of a width<br />
19%<br />
4 Widths<br />
6 Widths<br />
8 Widths<br />
Women<br />
Width according to FAGUS 52<br />
(Frequency of widths in all sizes)<br />
RESEARCH<br />
The foot is a part of the body and by its very nature<br />
three dimensional. Hitherto, however, selection of<br />
shoes has been based almost exclusively on shoe size,<br />
a one-dimensional measure of foot length. The width,<br />
i.e. a measure of ball girth, is given for only few shoes.<br />
In addition, no uniform set of tables exists for determining<br />
the width; instead, there are many tables<br />
which also differ from one another – albeit only slightly<br />
in most cases. Most people are unaware of their foot<br />
width. Of course, customers generally know whether<br />
they have wide or very narrow feet, if only because<br />
they have serious problems in finding properly fitting<br />
shoes.<br />
In order to supply 90 percent of the population with<br />
properly fitting shoes, each shoe size would have to<br />
be available in eight widths. But the costs would be<br />
prohibitive. If every shoe size were available in four<br />
widths, then 60 percent of customers could be properly<br />
provided for (Fig. 1). Yet even then, there would<br />
still be a substantial risk that shoes would not fit. Additional<br />
foot measurements should be introduced to<br />
facilitate correct choice, but that would drive up costs<br />
out of all proportion.<br />
Anatomical<br />
ball circumference<br />
260<br />
250<br />
240<br />
230<br />
220<br />
210<br />
200<br />
190<br />
Anatomical ball circumference<br />
Women (age dependent)<br />
15-20 21-30 31-40<br />
Age group (years)<br />
51-50 51-60 61-70<br />
- Sigma Mean value + Sigma<br />
Fig. 2: Variation of the anatomical ball girths<br />
of women
WHEN DoES A SHoE FIT?<br />
Search for Correlations<br />
Investigations for the new project were undertaken<br />
on the basis of the foot measurements recorded during<br />
the foot measuring campaign. To this end, the foot<br />
measurements were analysed and any correlations<br />
were sought which could be of value for improved<br />
shoe selection. Apart from circumference measurements,<br />
width and height also appeared to be of interest.<br />
However, these investigations did not lead to any<br />
useful solution because the measurements showed a<br />
huge range of variation but no unequivocal correlations.<br />
The anatomical ball girth, measured over the big<br />
toe and little toes joints, is mentioned as example: The<br />
mean value for women was 231.3 mm, but the variation<br />
was large for all age groups (see Fig. 2).<br />
In summary, it was concluded that all combinations<br />
of measurements can occur in feet. No foot types can<br />
be deduced from the measurements. This finding was<br />
considered unsatisfactory, especially since different<br />
foot shapes became apparent on evaluation of the<br />
measurements, as can be seen in Fig. 3.<br />
Table 1: Foot types<br />
Variant Limit of<br />
heel-instep<br />
width<br />
difference<br />
in mm<br />
Limit of<br />
instep-ball<br />
widht<br />
difference<br />
in mm<br />
Percentage<br />
of foottype<br />
A1<br />
Percentage<br />
of foottype<br />
A2<br />
Percentage<br />
of foottype<br />
B1<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Defining Different Foot Shapes<br />
A different approach to examination of the<br />
foot measurements was therefore adopted.<br />
The question posed was: What makes the<br />
difference between the individual foot<br />
shapes? The answer lies in the differences<br />
between the width measurements. These<br />
obvious differences were therefore studied.<br />
The measurements used were the maximum<br />
heel width at 20 percent of the foot length,<br />
the instep width at 50 percent of the foot<br />
length, and projected maximum ball width<br />
(Fig. 4).<br />
The difference between the individual measurements<br />
was calculated and the feet assigned to certain foot<br />
types (see Table 1). Foot types A1, A2, B1, were B2 defined.<br />
The letter of the alphabet describes the backfoot<br />
and the numeral the forefoot. Among the female test<br />
persons, a difference between heel width and instep<br />
width smaller than or equal to 17 mm classified the foot<br />
as type A. If the difference was greater than 17 mm, the<br />
foot corresponded to type B. At a difference between<br />
the projected ball width and the instep width less than<br />
or equal to 11 mm, the foot was of type 1; at a difference<br />
greater than 11 mm the foot was of type 2.<br />
Percentage<br />
of foottype<br />
16_9 16 9 5% 31% 20% 44%<br />
16_11 16 11 10% 25% 35% 30%<br />
16_12 16 12 14% 21% 42% 23%<br />
16_13 16 13 18% 17% 49% 16%<br />
14_11 14 11 5% 15% 40% 40%<br />
15_11 15 11 7% 20% 38% 36%<br />
16_11 16 11 10% 25% 35% 30%<br />
17_11 17 11 14% 31% 31% 25%<br />
18_11 18 11 19% 36% 26% 19%<br />
B2<br />
Fig. 3: Various foot shapes<br />
21
22<br />
Newsletter<br />
Innovative Method for Fitting Shoes<br />
This assignment procedure is illustrated by a number<br />
of examples:<br />
For a given foot the maximum heel width was 61 mm,<br />
the maximum instep width 77 mm, and the projected<br />
ball width 86 mm. The difference between the instep<br />
width and the heel width is then 77 – 61 = 16 mm, i.e. the<br />
difference is smaller than 17 mm; the<br />
backfoot is of type A.<br />
The difference between the projected<br />
ball width and the instep width<br />
is 86 – 77 = 9 mm, i.e. the difference<br />
is smaller than 11; the forefoot is of<br />
type 1. The complete foot was classified<br />
as type A1 (example in Fig. 4).<br />
In the case of another foot the<br />
maximum heel width was 64 mm,<br />
the maximum instep width 88 mm,<br />
and the projected ball width 104<br />
mm. The difference between the<br />
instep width and the heel width is<br />
then 88 – 64 = 24 mm, i.e. the difference<br />
is greater than 17 mm; the<br />
backfoot is of type B (see Fig. 5).<br />
The difference between the projected ball width and<br />
the instep width is 104 – 88 = 16 mm, i.e. the difference<br />
is greater than 11; the forefoot is of type 2. The<br />
complete foot was classified as type B2 (see Fig. 6).<br />
These different foot types cannot be obtained by conventional<br />
grading because the heel would be scaled<br />
up or down in proportion to the ball measurement.<br />
RESEARCH<br />
When Does a Shoe Fit?<br />
Fig. 4:<br />
Test person of<br />
foot type A1<br />
Fig. 5:<br />
Test person of<br />
foot type B2<br />
Last Development<br />
The foot measurements for all shoes sizes were subsequently<br />
sorted according to these foot types and the<br />
distribution of the various other foot measurements<br />
examined in order to be able to assign further measurements<br />
to these types. On the basis of these results<br />
the measurements were determined for lasts for closed<br />
street shoes with a flat toe spring. For sample size 37<br />
a heel width of 58 mm was assigned to the sole of the<br />
type A last, and one of 55 mm in the case of the type<br />
B last. A medium width, width number 5, corresponding<br />
to a girth of 215 mm was selected for the type A1<br />
foot, width number 6 (220 mm girth) for types A2 and<br />
B1, and width number 7 (225 mm girth) for type B2.<br />
Comparison of the types showed that types A2 and B1<br />
differed only in the heel width. For the tests a further<br />
last was produced as a combination of these two. Accordingly,<br />
type A2B1 differs only in the heel width of<br />
the last sole, which is 57 mm. The instep height was<br />
the same for all types at 65 mm.<br />
The same was done for court shoe lasts, for which<br />
somewhat different, narrower values were selected<br />
for the heel width. Type A had a heel width of 54 mm<br />
and type B a width of 50 mm. The court shoes had a<br />
heel pitch of 60 mm. No A2B1 combination last was<br />
made in this case because the more stringent fitting<br />
demands on this kind of shoe allow no room for compromises.<br />
Fig. 6: Test person with shoe type B2
WHEN DoES A SHoE FIT?<br />
Wearing Tests<br />
The lasts were used to make shoes for wearing tests.<br />
The feet of the test persons were measured and assigned<br />
to the corresponding foot type. All the shoes<br />
were tried on for evaluation, or, in the case of a readily<br />
recognisable foot type, the appropriate shoe was immediately<br />
selected. Evaluation was undertaken both<br />
by the test person and by the person carrying out the<br />
tests.<br />
The wearing tests showed that, in addition to the<br />
width, the fit of the heel is very important. Shoes of<br />
type B fitted test persons with a slender heel more<br />
comfortably than those of type A. In contrast, test persons<br />
with a wide heel felt better in shoes of type A.<br />
However, the test persons included a number of people<br />
for whom the available widths did not come into<br />
question because their feet required an even narrower<br />
width. Combination of the results of this project and<br />
greater gradation steps (see final report of AiF Research<br />
Project 14993) can assure a significantly better<br />
supply of correctly fitting shoes.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
The detailed results can be found in <strong>PFI</strong>’s final report<br />
on AiF Project 15857. The research project was funded<br />
by the Federal German Ministry of Economics and<br />
Technology via the German Association of Industrial<br />
Research Organisations (AiF) in accordance with a resolution<br />
adopted by the German Parliament.<br />
Contact:<br />
Dr. Monika Richter<br />
<strong>PFI</strong> Pirmasens e.V.<br />
Phone: +49 6331 - 249027<br />
E-Mail: monika.richter@pfi-germany.de<br />
23
24<br />
Newsletter<br />
Joint <strong>PFI</strong> and LGR Research Project<br />
The pronounced toxicity of chromium(VI) and the introduction<br />
of a limit value for chromium(VI) in leather<br />
articles of daily use have made elucidation of the<br />
mechanisms of chromium(VI) formation in leather a<br />
matter of prime concern. In a joint research project,<br />
the Test and Research Institute Pirmasens (Prüf- und<br />
Forschungsinstitut Pirmasens, <strong>PFI</strong>) and the Tanning<br />
School Leather Institute Reutlingen (Lederinstitut<br />
Gerberschule Reutlingen, LGR) have investigated<br />
how total chromium, soluble total chromium, and the<br />
substances naturally present in hides are interrelated<br />
with chromium(VI) formation in leather und leather<br />
goods.<br />
CHEMISTRY<br />
How is Chromium(VI) Formed<br />
in Leather and Leather Goods?<br />
Tests for contaminants in footwear and leather goods<br />
repeatedly reveal the presence of highly hazardous<br />
chromium(VI). In a recent laboratory study on<br />
60 shoes of various kinds, some of which contained<br />
several different kinds of leather, six were found to<br />
contain high levels of chromium(VI). Among the other<br />
54 shoes without conspicuous initial chromium(VI) values,<br />
chromium(VI) could be detected in 11 after they<br />
had been subjected to an ageing process in which the<br />
leathers were incubated for 24 hours at 80 °C. The<br />
German Federal Institute for Risk Assessment had<br />
long recommended a ban on leather goods with a<br />
chromium(VI) content exceeding 3 mg/kg. The eighteenth<br />
amendment to the German Consumer Goods<br />
Ordinance of 3 August 2010 therefore includes a provision<br />
for chromium(VI). Consumer goods exceeding<br />
the chromium(VI) limit value may no longer be placed<br />
on the market and must be removed from the market.<br />
This can mean serious economic damage for manufacturers<br />
and the trade.<br />
Chromium as Tanning Agent<br />
Tanning with chromium(III) salts is the principal<br />
method of leather tanning. Chrome-tanned leather<br />
is characteristically strong and supple. Its properties<br />
make it suitable for use in numerous products: for<br />
footwear and apparel, and also for furniture and<br />
car interiors.<br />
What is the Function<br />
of Chromium in Tanning?<br />
Leather is a product derived from animal hides preserved<br />
by tanning. During the tanning process the<br />
tanning agent chromium binds to the collagen in the
JoINT <strong>PFI</strong> AND LGR RESEARCH PRoJECT<br />
The Project and Its objectives<br />
The complete title of the research project is “Studies to<br />
Determine the Relations between Soluble Total Chromium<br />
as well as Hide Constituents and Chromium(VI)<br />
Formation in Leather and Leather Goods”. It was funded<br />
as IGF Project No. 15845 N of the Leather Research<br />
Association (Forschungsvereinigung Leder, FGL) by<br />
the German Federal Ministry of Economics and Technology<br />
through the German Federation of Industrial<br />
Research Associations (AiF) within the IGF programme<br />
for promoting industrial cooperative research and development.<br />
The objective of the joint research project undertaken<br />
by <strong>PFI</strong> and the Tanning School Leather Institute was to<br />
elucidate the interrelations between total chromium<br />
content, soluble total chromium content, the hide<br />
constituents, and the formation of chromium(VI) and<br />
to understand the mechanisms involved.<br />
hides. The leather thus does not shrink; it remains<br />
supple and retains its strength. The chromium(III)<br />
salts used in chrome tanning are only very slightly<br />
toxic since they are only poorly absorbed by the body.<br />
Chromium(III) can cause local skin irritation in sensitive<br />
persons. Extremely hazardous chromium(VI)<br />
can be formed from chromium(III) in reactions favoured<br />
by oxidation processes and alkaline pH<br />
values. According to our current state of knowledge,<br />
chromium(VI), in contrast to chromium(III),<br />
can penetrate the cell membrane. Chromium(VI)<br />
is highly toxic, allergenic, and carcinogenic.<br />
Procedure<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
In order to undertake the project, various upper and<br />
lining leathers were first produced: leathers with high<br />
and with low chrome tanning agent contents; with and<br />
without fixation; with various fatting agents; leathers<br />
of high layer thickness; and leathers with a high<br />
chromium(VI) content. Total chromium, total soluble<br />
chromium, and chromium(VI) were measured. What<br />
information is provided by these measured values?<br />
Total chromium refers to the total amount of chromium<br />
present in a leather. Its determination requires<br />
destruction of the leather by action of acid.<br />
Total soluble chromium designates that chromium<br />
fraction of a leather which can be dissolved out of<br />
the leather by the action of aqueous salt solutions resembling<br />
human perspiration without destroying the<br />
leather. This simulates the possible chromium exposure<br />
of a person that can result on wearing of leather<br />
products.<br />
Chromium(VI) is also dissolved out of leather by the<br />
action of aqueous salt solutions. The difference is that<br />
only chromium in the +6 oxidation state is determined<br />
in this case. The principal question is whether the three<br />
measured values are correlated, and if so, how? Laboratory<br />
tests for chromium(VI) are generally performed<br />
prior to or at the beginning of footwear production. It<br />
was therefore important to include the effects of storage,<br />
heat, light, and adhesives in the investigations.<br />
Chrome III<br />
oxidation<br />
Reduction<br />
Simplified representation of transformation<br />
of chromium(III) into chromium(VI)<br />
Chrome VI<br />
25
26<br />
Newsletter<br />
Joint <strong>PFI</strong> and LGR Research Project<br />
Results for Different Leathers<br />
Fatting and Amount of Chrome Tanning<br />
Agent Used<br />
The choice of fatting agent was crucial for chromium(VI)<br />
formation during leather production. In contrast, the<br />
animal hide constituents present in leather have no<br />
influence on the chromium(VI) values. Use of greater<br />
quantities of chrome tanning agent led to high contents<br />
of total chromium and soluble total chromium in<br />
leather. The amount of soluble total chromium could<br />
be reduced by fixation of the leather with dicarboxylic<br />
acids. No correlation could be seen between high total<br />
chromium contents or high soluble total chromium<br />
contents and the chromium(VI) content of the leathers.<br />
Ageing and UV Irradiation<br />
A considerable influence on chromium(VI) formation<br />
in leathers could be ascribed to ageing and UV irradiation.<br />
This is also apparent from studies on the different<br />
layers of leather. To this end, the leathers were split<br />
into four layers. The chromium(VI) contents proved to<br />
be higher in the outer layers directly exposed to the<br />
environment than in the inner layers.<br />
CHEMISTRY<br />
How is Chromium(VI) Formed<br />
in Leather and Leather Goods?<br />
Adhesives and Heat<br />
Furthermore, the effect of three different adhesives<br />
on chromium(VI) formation was also examined. Thus<br />
the leathers were treated with a natural latex adhesive,<br />
a synthetic latex adhesive, and a PU dispersion<br />
adhesive. The leathers were additionally subjected to<br />
heating to simulate the footwear production process.<br />
Application of adhesive led to significantly higher<br />
chromium(VI) contents in some of the tested lining<br />
leathers, whereas upper leathers showed hardly any<br />
increase in chromium(VI) levels. Adhesive treatment<br />
and heat tended to slightly reduce the chromium(VI)<br />
levels in leathers with a high initial chromium(VI) concentration.<br />
A slight increase in chromium(VI) levels<br />
was noted in the case of low initial chromium(VI) contents.<br />
Reducing Agents<br />
In addition, the effect of reducing agents on the<br />
chromium(VI) contents of leathers was also investigated,<br />
both in a vat process and after spray application.<br />
On the one hand, reducing agents prevent the formation<br />
of chromium(VI); on the other, they lower the<br />
concentration of existing chromium(VI). Use of reducing<br />
agents consistently leads to lower chromium(VI)<br />
contents of leathers. The reducing action also withstood<br />
treatment with heat and adhesives.<br />
Leather lining<br />
attached to shoe upper
JoINT <strong>PFI</strong> AND LGR RESEARCH PRoJECT<br />
The leather was split fourfold<br />
in order to examine the<br />
individual layers<br />
Tests on Footwear<br />
In addition to the studies on leather samples, items of<br />
footwear were also produced and the leathers subsequently<br />
examined in the laboratory. Upper and lining<br />
leathers with different contents of chrome tanning<br />
agent were selected for shoe production and two different<br />
adhesives were used. Four upper leathers and<br />
four lining leathers were used in one shoe, for the toe,<br />
the heel, the left side, and the right side, respectively.<br />
None of the leathers used had a chromium(VI) content<br />
exceeding 3.0 mg/kg prior to shoe production. In total,<br />
32 upper leathers and 32 lining leathers from the shoes<br />
were examined for their chromium(VI) content. None<br />
of the upper leathers used in the shoes showed increased<br />
chromium(VI) levels. Five of the lining leathers<br />
were found to have chromium(VI) values exceeding 3.0<br />
mg/kg. A long-term test of the shoes over a period of<br />
three months showed a slight increase of chromium(VI)<br />
values depending upon the amount of chrome tanning<br />
agent used. The increased chromium(VI) levels in the<br />
shoes could be greatly lowered by spray application<br />
of reducing agents. After a four-week treatment of<br />
the shoes with reducing agents, the individual leathers<br />
of the shoes were again examined with regard to<br />
their chromium(VI) contents. The reducing agent lost<br />
some of its potential, but the chromium(VI) levels of<br />
the leathers of the shoes still lay below the legal limit<br />
value for chromium(VI) of 3.0 mg/kg.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
The findings demonstrate that adoption of specific<br />
measures can minimise the risk of chromium(VI) formation<br />
in leather products – in the interests of preventative<br />
consumer health care. The complete research<br />
report is available from the contact address.<br />
Contact:<br />
Dr. Kerstin Schulte<br />
Head of Chemical Analysis and Research<br />
Prüf- und Forschungsinstitut Pirmasens<br />
Marie-Curie-Straße 19<br />
66953 Pirmasens<br />
Phone: +49 6331 2490 712<br />
Fax: +49 6331 2490 60<br />
E-Mail: kerstin.schulte@pfi-germany.de<br />
27
28<br />
Newsletter<br />
<strong>PFI</strong> Participates in Wet-White Round-Robin Test<br />
Mould Resistance of Leathers<br />
and Intermediate Products<br />
Mould infestation of raw materials and finished products<br />
repeatedly gives rise to considerable financial<br />
losses and may also adversely affect the health of employees.<br />
Such infestation is frequently triggered by a<br />
high water or moisture content of intermediate products<br />
that are susceptible to microbial attack and/or<br />
adverse climatic conditions (rainy season) in the production<br />
centres of the Far East. For this reason, tests<br />
for mould resistance of leather intermediate products<br />
are not only helpful but absolutely essential features<br />
of quality control. In this way, substandard materials<br />
can be eliminated and possible infestation and further<br />
spread of mould can be effectively prevented.<br />
MICRoBIoLoGY<br />
Tegewa (an association of manufacturers of textile,<br />
paper, leather, and fur auxiliaries and colourants, surfactants,<br />
complexing agents, antimicrobial agents,<br />
polymeric flocculants, cosmetic raw materials, pharmaceutical<br />
excipients, and allied products) addresses<br />
current topics relating to the above areas with the aim<br />
of offering its members and the market appropriate<br />
practical solutions.<br />
Last summer the leather auxiliary section of Tegewa<br />
set up the “Mould Resistance” Project <strong>Group</strong> which is<br />
concerned with questions surrounding this topic. The<br />
members of the Project <strong>Group</strong> come from industry and<br />
from research institutes.<br />
Over the years, there have been changes in the preservation<br />
methods used for leather products and intermediates.<br />
The question thus arises whether the reliable<br />
yet relatively straightforward laboratory method<br />
for testing the mould resistance of so-called wet-blue<br />
(chrome-tanned leather products) published in 1996<br />
by the above Section is also applicable to wet-white<br />
(glutaraldehyde-tanned leather products).<br />
To this end a round-robin test was carried out by five<br />
participants, including <strong>PFI</strong>, at the close of 2010.
Round-Robin Test Methodology<br />
The method is based on an agar diffusion test. Punched<br />
out specimens are placed with both the flesh side and<br />
the grain side in contact with an agar plate uniformly<br />
inoculated with spores of a given test organism and<br />
incubated at elevated temperature and moisture levels.<br />
The test organism, a mould fungus, then grows<br />
initially on the agar and, depending upon the state of<br />
preservation, possibly also on the specimen. The condition<br />
of the sample is evaluated on a weekly basis.<br />
Any inhibition zone appearing around the specimen is<br />
recorded and measured.<br />
If there is a lack of mould resistance (evaluation 1/A, A<br />
= growth area) mould growth generally begins at the<br />
outer edge and gradually proceeds over the test sample;<br />
the extent of growth was also measured.<br />
If preservation is adequate the samples will show no<br />
mould growth (evaluation 0/0) at the end of the incubation<br />
period or possibly also an additional zone devoid<br />
of fungal growth immediately surrounding the<br />
samples (evaluation 0/H, H = extent of inhibition zone<br />
in mm) and the material thus fulfils the demands of<br />
stability toward mould growth over this time interval.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Test samples, glutaraldehyde tanned „Wet white“<br />
Control plates with various test organisms (left to<br />
right): Aspergillus niger, Penicillium sp., Trichoderma<br />
viridae, Hormoconis resinae<br />
a b c d<br />
Mould formations due to bioburden, outer left on<br />
untreated samples (a); samples with three different,<br />
increasing concentrations of an active substance<br />
(right, b to d) exhibit mould resistance<br />
29
30<br />
Newsletter<br />
<strong>PFI</strong> Participates in Wet-White Round-Robin Test<br />
Mould Resistance of Leathers<br />
and Intermediate Products<br />
Round-Robin Test Procedure<br />
The original method was updated on the basis new<br />
findings and experience gained by the participants.<br />
The experts agreed to adopt a number of modifications,<br />
such as optimisation of the culture conditions<br />
and prolongation of the incubation time from 21 to<br />
28 days while retaining weekly evaluation. In addition,<br />
the range of test organisms was extended to include<br />
Hormoconis resinae, which can cause material damage<br />
and is frequently found on leather products. The range<br />
of test microorganisms thus comprises: Aspergillus sp.,<br />
Penicillium sp., Trichoderma viridae, and the abovementioned<br />
Hormoconis resinae. Use of a mixture of<br />
fungal spores (as in the original methods) was categorically<br />
excluded in the interest of obtaining reproducible<br />
microbiological results. Determination of the<br />
Mould resistance towards Penicillium sp. after<br />
seven days; inhibition zone formation in the case of<br />
treated samples (b to d)<br />
MICRoBIoLoGY<br />
bioburden and internal controls on untreated samples<br />
were also considered in revision of the procedure.<br />
Samples for the round-robin test were provided<br />
by Südleder GmbH & Co. Tests were performed on<br />
samples without active substance and with four<br />
different concentrations of the mould inhibitor<br />
2-(thiocyanomethylthio)benzothiazole (TCMTB). The<br />
content of active substance was determined at the Research<br />
Institute for Leather and Plastic Sheeting (Forschungsinstitut<br />
für Leder und Kunststoffbahnen, FILK),<br />
which also participated in the round-robin test.<br />
a b c d a b c d<br />
Mould resistance towards Aspergillus niger, untreated<br />
samples are completely covered by mould growth (a)<br />
and samples with a low degree of preservation only at<br />
the edges (b). Samples with a higher concentration of<br />
active substance exhibit adequate mould resistance (c, d).
Results and Conclusion<br />
A correlation exists between the actual concentration<br />
of the active compound and the resistance to<br />
growth of the test microorganisms. Untreated samples<br />
showed mould infestation after just a few days. Above<br />
a certain concentration of active substance all the samples<br />
prove resistant to mould attack, remaining free<br />
from infestation even after an incubation time of four<br />
weeks. Some of them even show inhibition zones over<br />
a period of two weeks, as in the case of Hormoconis<br />
resinae. Flesh and grain sides show only slight, if any,<br />
differences. Nevertheless, examination of both sides is<br />
urgently recommended.<br />
1/A<br />
0/0<br />
Trichoderma viridae<br />
0% 0,05% 0,1% 0,2%<br />
Agent concentration (in %)<br />
Concentration-dependent mould resistance<br />
towards Trichoderma viridae<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Summarising, it can be stated that the above updated<br />
method is suitable for testing and evaluating the<br />
mould growth resistance of wet-white.<br />
It should, however, be noted that stability to mould infestation<br />
tested under laboratory conditions does not<br />
represent an absolute guarantee of mould resistance.<br />
Additional conventional countermeasures against<br />
mould infestation are appropriate and advisable.<br />
The results of the round-robin test were presented<br />
at the Annual Meeting of the Association for Tanning<br />
Chemistry and Technology (Verein für Gerberei<br />
Chemie und Technik, VGCT) at ISC in May 2011.<br />
Further information:<br />
Dipl.-Biologin Michaela Würtz<br />
Phone: +49 6331 2490 550<br />
E-Mail: michaela.wuertz@pfi-germany.de<br />
7d<br />
14d<br />
21d<br />
28d<br />
31
32<br />
Newsletter<br />
Changes to ASTM E2149 Challenge Test Method<br />
Test Method for Antibacterial<br />
Activity Updated<br />
The American standard test method for determination<br />
of antibacterial activity – ASTM-E2149 – was updated<br />
at the end of 2010. The procedure is a so-called<br />
challenge test method which is used in the footwear<br />
industry, especially for composite materials and complex<br />
shoe components.<br />
State-of-the-art materials with an antibacterial finish<br />
are frequently used in the clothing sector, including<br />
shoes and shoe components, to minimise the side effects<br />
and consequences of bacterial attack.<br />
Shake flask test under dynamic contact conditions Sampling<br />
MICRoBIoLoGY<br />
Beyond the shores of the USA, the ASTM E2149 standard<br />
test method is widely used internationally for determination<br />
of the antibacterial activity of correspondingly<br />
finished materials and composite systems, such as<br />
insoles, in which the active antimicrobial substance is<br />
immobilised and not subject to diffusion or leaching.<br />
This test is used particularly frequently by surface finishers<br />
and developers of antibacterial products and by<br />
vendors who place goods advertised as having antimicrobial<br />
properties on the market and wish to perform<br />
random checks for purposes of quality assurance.
Procedure Widely Used<br />
in the Footwear Industry<br />
The advantage of this challenge test method is that it<br />
can be reproducibly performed in the laboratory, particularly<br />
on complex composite systems and samples<br />
that are non-planar or irregularly shaped, as is generally<br />
the case with footwear components. Moreover, in<br />
contrast to other test methods, no identical untreated<br />
control material is necessary to perform testing and<br />
evaluation of antibacterial activity. These features<br />
have led to widespread use of the method in the footwear<br />
industry.<br />
Plating of the samples for enumeration<br />
of the viable microorganisms<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
In this quantitative method, samples treated with<br />
antibacterial agents (and where appropriate also untreated<br />
control materials) are shaken in a bacterial suspension<br />
with a defined microbial concentration of a<br />
given test organism, hence the commonly used name<br />
‘shake-flask test’. The initial microbial concentration is<br />
first determined. After incubation under dynamic conditions<br />
for specified periods, the viable bacteria are<br />
enumerated and the antibacterial activity calculated.<br />
33
KBE<br />
1,0E+08<br />
1,0E+07<br />
1,0E+06<br />
1,0E+05<br />
1,0E+04<br />
1,0E+03<br />
1,0E+02<br />
1,0E+01<br />
1,0E+00<br />
34<br />
Newsletter<br />
MICRoBIoLoGY<br />
Changes to ASTM E2149 / Challenge Test Method<br />
Test Method for Antibacterial<br />
Activity Updated<br />
Incubation of the culture medium plates<br />
Example of a material showing antibacterial<br />
activity towards Klebsiella pneumoniae<br />
0h<br />
1h<br />
5,0E+05<br />
2h<br />
6,9E+04<br />
3h<br />
3,3E+06<br />
4h<br />
5h<br />
6h<br />
7h<br />
8h<br />
9h<br />
10h<br />
11h<br />
12h<br />
13h<br />
Time<br />
14h<br />
15h<br />
16h<br />
17h<br />
Antibacterial Activity Can Also<br />
Be Expressed in “Log Steps”<br />
According to the updated version of the test method,<br />
the antibacterial activity can be stated, as desired, either<br />
as a percentage reduction of microbial count or as<br />
the difference of the decadic logarithms, known colloquially<br />
as ‘log steps’. These are just two different ways<br />
of expressing the laboratory values determined.<br />
Depending upon the material, the antibacterial agent,<br />
and the field of application, differing requirements<br />
have to be satisfied which need to be agreed between<br />
the contracting parties. The above standard method is<br />
used to determine antibacterial activity, not to evaluate<br />
the results.<br />
A test for antibacterial efficacy should always include<br />
independent testing towards a gram-positive and a<br />
gram-negative bacterium, because the two differ in<br />
their cell structure. Antibacterial efficacy is assured<br />
only if there is activity against both groups of bacteria.<br />
18h<br />
19h<br />
20h<br />
21h<br />
22h<br />
23h<br />
4,2E+07<br />
24h 1,0E+00<br />
Material<br />
Control
Changes Concerning<br />
the Test organisms<br />
Changes to the standard concern mainly the test organism.<br />
In place of the gram-negative test organism<br />
Klebsiella pneumoniae used in previous versions of the<br />
standard, the latest version stipulates the closely related<br />
organism Escherichia coli, which is easier to handle<br />
in the laboratory. Nevertheless, tests can only be performed<br />
by trained personnel in a Category 2 microbiological<br />
safety laboratory because both organisms are<br />
potential pathogens.<br />
The failure to specifically address the gram-positive<br />
bacteria differing in their cell structure in the course of<br />
the revision process remains a drawback. In the stated<br />
objective of the revised standard, mention is made of<br />
its use for a wide range of microorganisms, meaning<br />
that the use of additional or other microorganisms is<br />
permissible.<br />
<strong>PFI</strong> therefore continues to offer the existing, accredited<br />
test method with the test organisms Staphylococcus<br />
aureus (gram-positive bacterium) and either Klebsiella<br />
pneumoniae or Escherichia coli (gram-negative<br />
bacterium).<br />
Although the ASTM E2149 standard test method for<br />
determining the antibacterial activity of antimicrobial<br />
treated specimens was updated in 2010, only modest<br />
changes were actually made.<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Enumeration of viable microorganisms:<br />
Each colony (spot) corresponds to a viable<br />
bacterial cell in the original sample<br />
Participants in a seminar on this and other test methods<br />
for determining antimicrobial efficacy towards<br />
bacteria and microfungi, held in late May at the International<br />
Shoe Competence Center in Pirmasens, were<br />
able to gain a deeper insight into this topic.<br />
Further information:<br />
Diplom Biologin Michaela Würtz<br />
Phone: +49 6331- 24 90 550<br />
E-Mail: michaela.wuertz@pfi-germany.de<br />
35
36<br />
Newsletter<br />
By No Means Trivial<br />
Shoe Accessory with Core Strength<br />
Everybody is familiar with them. Everybody uses<br />
them. Even oetzi, the famous glacier mummy, is considered<br />
to have been aware of their great advantages<br />
and every child has to laboriously learn how to tie<br />
them. We are talking shoelaces. Yet although it is hard<br />
to imagine everyday life without shoelaces, only few<br />
people have probably ever asked how they are actually<br />
made. Since this question has been put to us, we<br />
would like to provide an insight into shoelace production.<br />
Shoelace with a<br />
tubular knitted core<br />
PHYSICS<br />
Whether they are called shoelaces, bootlaces, or shoestrings,<br />
these generally braided or woven textile products<br />
have long been in use and come in a wide variety<br />
of shapes and designs: round and flat variants are just<br />
as common as finely worked laces worthy of wedding<br />
shoes or coarse and robust laces for doing up work<br />
boots.<br />
Sometimes the surface has been treated, sometimes it<br />
has not. Colour is also of optical importance, with both<br />
plain coloured and multicoloured laces being present<br />
on the market. The material used also differs. While<br />
some laces are made of natural fibres such as cotton,<br />
others consist of man-made fibres such as polyethylene<br />
or polyamide, of mixed fibres, or even of leather.<br />
The structure and material used largely determine the<br />
properties of the laces.
Which Shoelace<br />
is Suitable for Which Shoe?<br />
Or more fittingly: What must a shoelace be able to<br />
endure and what should it look like? These are in<br />
fact the principal aspects determining the proper<br />
choice:<br />
Since professional, work, safety, or hiking footwear<br />
has to withstand substantially greater stresses than<br />
lightweight leisure shoes, the laces clearly have to<br />
cope with more stringent demands. <strong>Here</strong> it is recommended<br />
to use thick, robust, high tensile strength<br />
laces made of synthetic fibres. Ideally, they should<br />
also have a round cross section because they can then<br />
accommodate a core at their centre – as described in<br />
this article – which enhances their strength. Shoelaces<br />
made in this way resist abrasion and withstand<br />
high tensile forces better than flat laces made of<br />
cotton. Anybody who has tried their hand at mountaineering<br />
will certainly appreciate the importance<br />
of strong laces and the security of firmly laced-up<br />
footgear.<br />
Casual leisure footwear or seasonal goods which just<br />
happen to be in fashion are subject to far less stress.<br />
Imagination knows no bounds with regard to material,<br />
colour, and production method. Even shoes with<br />
zip fasteners may have additional laces. Their original<br />
purpose as a means of closing a shoe no longer<br />
plays any role. The laces merely serve as decoration.<br />
The visual appearance and the colour of laces and<br />
the way in which they are tied have been playing an<br />
ever-greater role in recent years. There are even web<br />
pages devoted to the art of lace tying, which present<br />
a wealth of extraordinary and quirky ways of lacing<br />
shoes – just try googling “tying shoelaces”!<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
In the sports sector, flat, flexible, and extensible<br />
laces have proved their value for running shoes because<br />
they are not so stiff as thick round laces. The<br />
elasticity of such shoelaces also assures a firmer fit<br />
of the shoes. Moreover, knots in such laces do not<br />
come undone so quickly. This distinct practical advantage<br />
predestines the flat variants for use in children’s<br />
shoes: fewer undone shoelaces mean fewer<br />
tumbles.<br />
There can be many reasons for shoelaces coming undone:<br />
On the one hand, the choice of material plays<br />
an importance role. If it is fairly rough it will offer<br />
more resistance to opening of knots and bows. On<br />
the other hand, the thickness and structure of the<br />
laces (density of braiding) will have an effect on their<br />
stiffness. The more inflexible the laces, the easier the<br />
carefully laced-up shoe will come undone. In addition<br />
to starting material and method of production,<br />
substances applied to the material in the course of<br />
production also play an important role. They may<br />
influence not only the roughness but also the flexibility<br />
of the laces. There is currently no standard<br />
test proceedure for assessing how readily shoelaces<br />
come undone during wear or which laces have superior<br />
properties in this respect compared to competing<br />
products. However, <strong>PFI</strong> does undertake a test<br />
to estimate the probability that a knot will come<br />
undone, paying due attention to structure, stiffness,<br />
and frictional properties of laces and material.<br />
On no account should we forget the kind of footwear<br />
which has to meet particularly stringent demands,<br />
such as firefighter boots. These have to withstand<br />
heat and fire and should clearly never catch<br />
alight. They therefore contain a certain amount of<br />
fire retardants.<br />
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By No Means Trivial<br />
How a Braided<br />
Shoelace Is Made<br />
Shoelaces are produced on braiding machines. Yarns<br />
supplied for processing first have to be rewound onto<br />
special bobbins suitable for use on braiding machines.<br />
The bobbins fully wound with yarn are placed on carriers.<br />
These are mounted on flyer wheels (Fig. 1) which<br />
rotate continuously during the braiding process.<br />
PHYSICS<br />
Shoe Accessory with Core-Strength<br />
Fig. 1: Herzog braiding machine with two braiding<br />
heads and 16 bobbin carriers (source: August Herzog<br />
Maschinenfabrik GmbH & Co. KG)<br />
When the braiding machine is set in motion (see Fig.<br />
2), the bobbin carriers travel – some in a clockwise direction,<br />
some in an anticlockwise direction – in a serpentine<br />
fashion from flyer wheel to flyer wheel (cf.<br />
Fig. 1). On production of round braids and most flat<br />
braids, these form a circle with the braiding head at<br />
the centre. This where all the yarns come together to<br />
form the braid (cf. Fig. 1). While the bobbin carriers<br />
travel over the flyer wheels they sometimes come close<br />
to the braiding head and are sometimes more distant.<br />
In this way the yarns become intertwined to generate<br />
the visible structure of the braid.<br />
Fig. 2: Schematic representation of the path of the<br />
bobbin carriers (red, blue) on flyer wheels arranged<br />
in a circle
The various colour and structural effects of shoelaces<br />
are determined by the number and nature of the flyer<br />
wheels and the yarn, among other factors. Whether<br />
round or flat braids are produced is also decided at<br />
this point.<br />
Round shoelaces have yet another special feature: In<br />
addition to their visible braiding, forming the sleeve,<br />
they often have a core concealed in their interior. This<br />
usually consists of other textile materials. e.g. yarns,<br />
ply yarns, or tubular knitted material. Core material<br />
is fed into the machine separately during production<br />
and is enclosed by a braided sleeve made up of the<br />
subsequently visible yarns. But why take all the trouble?<br />
Because the core endows shoelaces with additional<br />
desired properties: they weigh more, exhibit a<br />
greater tensile strength, or have better extensibility<br />
than those without a core.<br />
The braided cords of several metres length are clearly<br />
much too long for use as shoelaces. They are therefore<br />
cut to length. The tips have to be fixed in a plastic<br />
or metal sheath, known as an aglet, to prevent them<br />
from unravelling. In the case of synthetic fibres, the<br />
ends can be welded together ultrasonically to form<br />
a moulded tip aglet. Alternatively, aglets can be produced<br />
by crimping a piece of metal onto the shoelace<br />
or by forming a plastic sleeve directly on the lace. The<br />
aglets serve not only to protect the tips but also as an<br />
aid in threading the laces through the eyelets. Oetzi<br />
can only have dreamed of such convenience!<br />
01.2011<br />
Magazine of the Test and Research Institute Pirmasens<br />
Tests<br />
for Shoelaces at <strong>PFI</strong><br />
<strong>PFI</strong> offers the following standard tests<br />
for shoelaces:<br />
Abrasion (according to DIN EN ISO 22774)<br />
- laces abrading against each other<br />
- laces abrading against eyelets<br />
Tensile strength and elongation<br />
(based on DIN EN ISO 18691)<br />
- testing in as-received condition<br />
- testing after abrasive wear<br />
Pull-out strength for aglets<br />
Moreover, <strong>PFI</strong> can perform other, albeit<br />
non-standard tests in special cases:<br />
Water fastness<br />
Mass per unit length<br />
Further information:<br />
Dipl.-Ing. (FH) Kai Tinschert<br />
Phone: +49 6331 2490 - 16<br />
E-Mail: kai.tinschert@pfi-germany.de<br />
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