Here - PFI Group

When Does a Shoe Fit? 

How is Chromium(VI) Formed 

in Leather and Leather Goods? 

Mould Resistance 

of Leathers and Intermediate Products 

Still Just a Dream? 

The Eco Shoe 

Newsletter 

01.2011 

Magazine of the Test and Research Institute Pirmasens

2 

Newsletter 

Contents 

Contents 

Contents 

................................................................... 02 

Editorial ................................................................... 04 

News 

Radioactive Contamination 

of Goods from Asia? .................................................. 05 

Point of Shoes Well Received .................................... 06 

International Footwear Trade Expert ....................... 08 

Kai Tinschert Joins Physics Section ............................. 09 

Professor Klaus Mattil Turns 75 ................................. 09 

DSF Alumni Reunion in August ................................. 10 

Biotechnology 

The Eco Shoe – Still Just a Dream? ............................ 12 

Pirmasens Energy Park All Set to Go ......................... 16 

PFI Expands International 

Research Activities ...................................................... 18 

Research 

01.2011 

01.2011 

When Does a Shoe Fit? .............................................. 20

Chemistry 


in Leather and Leather Goods? ................................ 24 

Microbiology 

Mould Resistance of Leathers 

and Intermediate Products ....................................... 28 

Changes to ASTM E2149 / 

Challenge Test Method ............................................. 30 

Physics 

Shoe Accessory with Core Strength .......................... 36 

Masthead 

Publisher: PFI Test and Research Institute Pirmasens 

Prüf- und Forschungsinstitut Pirmasens e. V. 

Member of PFI Group 

Director of Institute: Dr. Gerhard Nickolaus 

Address: Marie-Curie-Straße 19 

66953 Pirmasens / Germany 

Phone: +49 6331 2490 0 

Fax: +49 6331 2490 60 

E-Mail: info@pfi-germany.de 

Internet: www.pfi-germany.de 

Editor: Elisabeth Rouiller 

Translation: Tony Rackstraw 

Design Concept and Layout: 

Konzept fünf - Agentur für Werbung und Design 

Internet: www.konzept-fuenf.de 

01.2011 

Magazine of the Test and Research Institute Pirmasens 

Pictures: 

Fotolia (p. 5), 

August Herzog Maschinenfabrik GmbH & Co KG (p. 38), 

PFI, ISC 

Reprint – extracts included – only with authorisation 

of the PFI. 

The online-version of the PFI-Newsletter is available 

under www.pfi-group.org/newsletter.html 

3

4 

Editorial 

Newsletter 

Dear Readers, 

The latest issue of the PFI Newsletter has now been 

published. We trust that it will again provide you 

with a wealth of valuable and interesting information 

about the research activities and services offered by 

PFI. Like any other dynamic organisation, PFI is in a 

state of constant flux; traditional areas of activity are 

contracting, new areas are expanding. 

EDIToRIAL 

Thus our Biotechnology Department is currently moving 

ahead under full steam, undoubtedly having received 

an additional boost from recent events in Japan. 

Alternative approaches to power generation, decentralised 

solutions for conservation of fossil resources 

and reduction of effective CO emissions, as well as the 

2 

synthesis of raw materials and plastics from renewable 

resources are all much in demand. We have our eye on 

the ball. Of course, we cannot claim to be able to solve 

the fundamental problems of energy generation, but 

we can make an important contribution to the mosaic 

of future energy supplies. For our original area of core 

competence, the footwear industry, attractive possibilities 

resulting from use of biodegradable polymers 

produced from renewable resources can open up new 

markets. 

We greatly appreciate your interest in current developments 

and projects undertaken at PFI. Do not hesitate 

to contact us if you have any questions or suggestions. 

Contact details of our department heads will be found 

in this publication. And, of course, I am also glad to be 

of assistance wherever I can. 

Yours Dr. Gerhard Nickolaus 

PFI Group

NEWS 

The accident at the Fukushima nuclear power station 

in Japan and the subsequent escape of radioactive 

nuclides, which have been and still are at the centre 

of world-wide attention, are a cause for concern for 

companies which manufacture goods in the Far East 

or import goods produced in factories located in that 

region. After all, those persons who place products on 

the market are ultimately responsible for them. The 

question arises whether the goods are radioactively 

contaminated, and if so to what extent. It is also necessary 

to establish whether, and if so which, safety 

measures are appropriate, for example whether tests 

for radioactive contamination prior to shipment are 

advisable. 

In the estimation of the German Federal Institute for 

Risk Assessment and the Federal Ministry of the Environment, 

Nature Conservation, and Reactor Safety, 

goods from other Asian countries (such as China or 

India) were not subject to any specific threat of radioactive 

contamination at the time of going to press. 

Hence footwear manufacturers with production facilities 

in Asian countries other than Japan need not expect 

any such risks and therefore need not adopt any 

additional precautionary measures. It is difficult to assess 

the situation regarding goods from Japan itself. 

Shipping companies and airlines have adopted appropriate 

measures and have avoided or continue to 

avoid the area. 

Goods entering Germany from Japan are subjected 

to random testing for radioactivity by the customs 

authorities. EU-wide fast-track legislation has been 

enacted and direct safety precautions introduced for 

foods imported from Japan, which pose a significantly 

greater risk of radioactive contamination and an associated 

health hazard for the consumer. 

01.2011 


Possible Consequences of the Nuclear Accident at Fukushima 

Radioactive Contamination 

of Goods from Asia? 

A direct threat of radioactive contamination in and for 

Germany is ruled out by experts. However, the situation 

regarding consumer goods may change at short notice 

in view of the dynamic course of developments. 

Current information about the situation both in general 

and with regard to the consequences, particularly 

in Germany, can be found at: http://www.bfr.bund.de 

or http://www.bmu.de. 

Further information: 

Dipl.-Biologin Michaela Würtz 

Phone: +49 6331 2490 550, 

E-Mail: michaela.wuertz@pfi-germany.de 

5

6 

Newsletter 

The third Point of Shoes – International Fair for Fashion, 

Materials and Production (PoS), which took place 

at Pirmasens on 19 and 20 April, got off to a resounding 

start. Although the event took place during the Easter 

holiday period, almost 450 visitors were present on 

both days of the show and displayed an avid interest 

in the offerings of the 77 exhibitors. “Almost all the 

German footwear manufacturers were represented, 

meaning that we have attained the important goal of 

again attracting the domestic companies en bloc to 

Pirmasens”, summarised PoS organiser Uwe Thamm. 

Shoe machines were a special feature of this PoS; 15 

companies showcased their innovations. This technology 

platform will be featured every two years. And 

the PoS lecture programme, devoted this time to the 

Keynote Topic of sustainability, generated keen interest. 

“According to the latest available statistics dating from 

2009, the German footwear industry comprises 45 companies 

with more than 50 employees – and the registration 

data clearly show that the PoS attendees represent 

the entire domestic footwear sector”, says Uwe Thamm. 

“Companies which for many years have only travelled 

to Bologna are now coming back to Pirmasens. And 

most importantly: The decision makers are coming.” 

NEWS 

High Level of Visitor Acceptance, Top-Quality Lectures 

Point of Shoes 

Well Received 

“We were surprised by the quality of the discussions 

and were able to establish new contacts”, said 

Christopher Thornhill of Molina & Bianchi. 

Confirmation comes from the exhibitors: “The delegations 

coming to the show are generally made up of just 

two or three people, but they are very knowledgeable 

experts who are authorised to make decisions. Window 

shoppers and gawkers, on the lookout for cookies 

and ball-point pens, don’t come here”, according 

to Sam Neuer of the Zweibrücken-based company Innovatec. 

“We were surprised by the quality of the discussions 

and were able to establish new contacts; our 

expectations were thus surpassed”, said Christopher 

Thornhill of Molina & Bianchi. A hint of reservation 

was nevertheless expressed by some of the exhibitors: 

“It could all be somewhat more international.”

NEWS 

“We shall gladly pursue that point”, was the response 

of Uwe Thamm. “Now that we have attained our 

first objective, that of bringing the German footwear 

manufacturers back to Pirmasens, and now that Italian, 

Spanish, Portuguese, Czech, and even Chinese 

companies number among the exhibitors at PoS, we 

shall initially concentrate on attracting visitors from 

neighbouring countries. However, we should not expect 

miracles: Attracting international visitors will 

take time. But we are working on it.” 

The concluding discussion, chaired by Petra Salewski, 

Editor-in-Chief of the trade journals Schuhkurier and 

Steptechnik, has meanwhile become a traditional 

feature of PoS. The conclusion to be drawn from this 

discussion, attended mainly by exhibitors, was that no 

consensus can be reached in the matter of dates: The 

proponents of an earlier date and of a later date split 

into two fairly irreconcilable groups. And then there 

are additional constraints imposed by space allocation 

in the exhibition halls and public holidays. “The next 

PoS will take place on 3 and 4 November 2011, as was 

decided on the basis of exhibitor and visitor questionnaires 

in September 2010. In November we shall know 

the key data for 2012 and again strive to find ‘ideal’ 

dates”, explained Thamm. 

01.2011 


PoS organiser and ISC Head 

Uwe Thamm gave a positive assessment 

of the April Point of Shoes 

It has already been decided that the November PoS 

Fair will close at 2 p.m. on the second day. The second 

day of the event is still necessary, even if there are not 

so many visitors as on the first day: After all, about one 

third of the attendees only came on the second day. 

It has also been decided to move the open discussion 

session with exhibitors and visitors forward to 5 p.m. 

on the first day. 

The New Keynote Topic for the November PoS will be 

“Ten Years into the Future. Global Scenarios for the 

European Footwear Industry 2021”. 

“And another matter of great concern to us is the provision 

of a WLAN connection in the exhibition halls”, 

was Uwe Thamm’s final observation. “We sincerely 

hope that the City of Pirmasens can arrange for its installation 

between now and the next PoS.” 

Contact 

Point of Shoes contact partner at ISC is Steffen Korf. 

E-Mail: steffen.korf@isc-germany.com 

Phone: +49 (0)6331 145334-17 

Fax: +49 (0)6331 145334-30 

Further information can be found at 

www.point-of-shoes.com. 

PoS is organised by: 

International Shoe Competence Center 

Pirmasens gGmbH 

Director: Dipl.-Ing. (FH) Uwe Thamm 

Marie-Curie-Straße 20 


Phone: +49 6331 145334-0 

E-Mail: info@isc-germany.com 

Internet: www.isc-germany.com 

7

8 

Newsletter 

The Chamber of Industry and Commerce (Industrieund 

Handelskammer, IHK) and the International 

Shoe Competence Center Pirmasens have together 

launched a new certification course: Qualification as 

“International Footwear Trade Expert” meets a real 

demand and can be completed over a period of nine 

weekends. 

The “International Footwear Trade Expert” course is 

designed for employees of footwear manufacturers, 

suppliers to the footwear industry, and footwear dealers 

without a background in footwear. The participants 

acquire the general and footwear-specific know-how 

necessary for a job in the international shoe trade. 

72 Hours Packed Full of Challenges 

The new course can be completed on nine Saturdays 

by persons in regular employment and concludes with 

a certification exam. The participants will spend six of 

the nine Saturdays at ISC Germany, where they can 

benefit from the facilities of the ISC “training factory”, 

and three at the Chamber of Industry and Commerce 

in Pirmasens. The course covers the following topics: 

International trade and customs procedures 

Logistics 

Quality demands placed on footwear 

Certificates of origin 

Makes, production methods 

Footwear terminology and footwear English 

Business fundamentals 

Complaints management 

Hazardous substances 

NEWS 

New IHK / ISC Certification Course 

International 

Footwear Trade Expert 

Future footwear trade experts will be able to begin 

their training at ISC Germany in the course of 2011 

“Today’s footwear industry is totally internationalised, 

which also means that the procurement chains 

are becoming ever longer and more complex”, according 

to Uwe Thamm, Head of ISC Germany. “The new 

certification course fills a training gap by providing, 

in compact and highly practical manner, the specialist 

knowledge necessary to confidently cope with all 

aspects of procurement.” 

The first footwear trade experts can start the course in 

the fourth quarter of 2011 and receive their certificate 

in the first quarter of 2012. The course will cost approximately 

1700 Euro. 

Contact: 

Dipl.-Ing. Uwe Thamm 

International Shoe Competence 

Center Germany gGmbH 



Phone: +49 6331 14 53 34 0 

E-Mail: info@isc-germany.com´ 

Internet: www.isc-germany.com

NEWS 

Welcome to the Team 

Kai Tinschert 

Joins Physics Section 

Kai Tinschert completed his studies for a Diplom-Ingenieur 

degree in textile engineering specialising in 

surface engineering at the Pirmasens Campus of the 

Kaiserslautern University of Applied Sciences in August 

2009. He went on to gain practical experience at 

a leading manufacturer of special elastic fabrics for 

medical products. 

In January 2011 he joined the Physical Materials Testing 

and Research team at PFI. After first familiarising himself 

with all areas of activity and procedures, his main 

field of work will be in research and testing of textiles. 

Congratulations 

01.2011 


Professor Klaus Mattil Turns 75 

A thoroughbred shoemaker, exceptionally gifted engineer 

and teacher, ever-helpful colleague, and dyedin-the-wool 

native of the Palatinate is how we can 

best describe Professor Klaus Mattil. over the 30-year 

period from 1969 to 1999 he headed the Technical Department 

of PFI. on 3 May 2011 he celebrated his 75th 

birthday. The entire staff at PFI joins together in congratulating 

him on this occasion. 

This living idea generator Klaus Mattil has instigated 

innumerable projects and developments, and he continues 

to work with an enormous level of commitment 

to this day – far beyond the usual age of retirement. 

Particularly impressive is the energy he invested in his 

pioneering and trend-setting activities at PFI, and subsequently 

as PFI consultant and professor at Kaiserslautern 

University of Applied Sciences, where he continues 

to communicate his profound knowledge to students. 

“My wish for the footwear world is that Professor Mattil 

will long continue to place his knowledge and his energy 

in its service”, is how PFI Director Dr. Gerhard Nickolaus 

expressed his sentiments. “Congratulations, Professor 

Mattil, and long may you carry on the good work!” 

9

10 

Newsletter 

German College of Footwear Design and Technology 

DSF Alumni Reunion 

in August 

Just over two years ago, students and members of the 

teaching staff of the German College of Footwear Design 

and Technology (Deutsche Schuhfachschule, DSF) 

undertook a study trip to Portugal to visit a number of 

footwear factories. The trip was, of course, interesting 

and informative. However, among the highlights 

of the excursion, top place went to the discussions 

held with DSF alumni who now live and work in Portugal. 

In fact, these meetings were so interesting that 

the wish arose to pursue exchange of information 

and experience with other DSF alumni, wherever they 

might be in the world. Thus the idea of organising an 

inter-year reunion for DSF graduates was born. 

open-ended clicking presses 

at the Footwear College 

in the mid-1950s 

NEWS 

A date has now been set for this meeting: Alumni of all 

entry years of the German College of Footwear Design 

and Technology as well as friends and sponsors of the 

college are cordially invited to the grand reunion starting 

at 5 p.m. on 20 August 2011. The meeting points 

are located on the premises of the German College of 

Footwear Design and Technology at the International 

Shoe Competence Center (ISC Germany, Marie-Curie- 

Str. 20, 66953 Pirmasens) and at the Pirmasens Festival 

Hall from 7 p.m. onwards. 

The new premises of the Footwear College at ISC can 

be viewed during a champagne reception starting at 

5 p.m. A photo exhibition will tell the history of the 

Footwear College from its foundation in 1927 right 

up to the present day. The pictures illustrate everyday 

aspects and highlights in the life of the Footwear College 

and also track changes in the facilities and equipment 

at the school in the course of time. Of course, 

class photos of all the graduation years are an absolutely 

essential component of any such exhibition. Numerous 

exhibits will also relate individual stories from 

the long history of our College. All participants will 

receive a brochure showing highlights of this exhibition. 

Anybody who has additional photos or materials 

is kindly asked to make these documents available for 

20 August.

The response of alumni has been so overwhelming 

that the main celebration originally planned to take 

place on the premises of ISC had to be relocated to the 

Pirmasens Festival Hall. Graduates are eagerly anticipating 

this evening and meeting and conversing with 

former students and teachers. In order to facilitate 

planning of the event, all interested persons should 

register as soon as possible and inform the Footwear 

College of their contact details by e-mail or letter. A 

registration form can be found at www.bbspirmasens. 

de. Further information will be distributed prior to the 

meeting on 20 August. And do not forget to inform all 

alumni with whom you have kept in touch! 

Contact 

Deutsche Schuhfachschule 

at BBS Pirmasens 

Adlerstraße 31 


Phone: +49 (0)6331-24010 

Fax: +49 (0)6331-240120 

Internet: www.bbspirmasens.de 

E-Mail: schuhfachschule@freenet.de 

01.2011 


Modern clicking presses and cutting tables 

in the well-equipped machine shop of ISC, 

the new home of the German College of 

Footwear Design and Technology 

11

12 

Newsletter BIoTECHNoLoGY 

Joint Project of PFI and Kaiserslautern University of Applied Sciences 

The Eco Shoe – Still 

Just a Dream? 

Just imagine there were such a thing, a 100 percent 

eco shoe … no recycling problems, great consumer 

acceptance, tomorrow’s ultimate product. Today’s 

reality looks very different: up to the present shoes 

remain a disposal nightmare. The situation is untenable 

and that is why PFI’s Biotechnology Department 

and Kaiserslautern University of Applied Sciences are 

planning a joint project with the principal goal of developing 

a shoe that can be bio-recycled. 

Two facts are indisputable: Consumer demand for ecofriendly 

products is steadily increasing and regulatory 

demands are becoming ever more stringent. For this 

reason PFI has set up a research project bearing the 

name “Development of Shoe Production Based on Renewable 

and Fermentable Materials”. The declared 

aim is 100 % bio-recycling of footwear at the end of 

its product life cycle together with all waste from the 

production process, with complete utilisation of all the 

material and energetic resources present in the materials. 

Another aim of the project is to promote sales of 

ecologically valuable footwear in Germany and thus 

to open up a new market for SMEs belonging to the 

footwear industry and its suppliers. 

Greater Environmental 

Consciousness 

More and more enquiries about eco-friendly products 

are reaching footwear manufacturers and PFI; a sure 

indication that the ecological awareness of consumers 

is on the increase. Topics such as sustainable material 

and product development, energy efficiency, 

and conservation of resources are of interest to everincreasing 

numbers of consumers or to that steadily 

growing group of person who consciously strive 

to pursue an eco-friendly lifestyle. Whether or not a 

product has been sustainably developed and produced 

clearly influences purchasing decisions made by these 

consumers. At the same time, manufacturing industry 

has understood – not least because of increasing material 

and energy prices – that sustainable operation 

and effective, and where possible waste-free, utilisation 

of resources are worthwhile. While earth-muffiny 

niche products have long been available, the footwear 

industry has now begun large scale use of materials 

which fulfil two principal purposes: On the one hand, 

they yield products of excellent ecological value manufactured 

by sustainable production processes wherever 

possible; on the other, they permit recycling of as 

many as possible of the raw materials and components 

used in production which are still present at the end 

of the product life cycle. In a parallel development, increasingly 

stringent regulations are compelling companies 

to recycle ever greater proportions of their 

waste and to design their products in compliance with 

ecological standards.

THE ECo SHoE - STILL JUST A DREAM? 

Footwear Problems: 

Material Diversity and Composites 

The footwear industry faces the particularly challenging 

task of offering ecologically valuable products in 

combination with efficient utilisation of resources, because 

a shoe represents a combination of widely differing 

materials. Furthermore, only limited use is presently 

made of ecologically valuable materials. 

An automated separation unit for all materials would 

give rise to certain ecological burdens. It would also 

significantly increase disposal costs. Unlike in the electrical 

and electronics industry, for example, which 

processes noble metals whose recycling is definitely 

worthwhile, footwear does not contain any high-price 

materials. It is therefore questionable whether such 

a sorting unit would be really worthwhile. If such a 

separation unit for shoes were to operate profitably, 

it could only do so by processing comparatively large 

amounts of waste. That would create disposal problems, 

above all for SMEs. In addition, only thermoplastics 

and metals would be to some degree recyclable, 

all the other waste could only be utilised thermally. It 

would also be necessary to demonstrate that the energy 

generated exceeds the amount of energy invested 

in the separation process. 

01.2011 


Project partner of PFI is the Western Palatinate Institute 

of Plastics Engineering on the Pirmasens Campus 

of Kaiserslautern University of Applied Sciences 

Conventional approaches to the recycling of industrial 

wastes from footwear production are based either on 

the principle of reutilising certain classes of substances, 

which can be admixed to a certain extent with new 

material, or on the principle of thermal utilisation. 

However, the (largely fossil) material resources would 

be lost on combustion. At the same time, residues 

proving difficult to dispose of, such as slag or spent 

combustion plant filters, would also arise. 

13

14 

Newsletter 

Joint Project of PFI and Kaiserslautern University of Applied Sciences 

The Eco Shoe – Still 

Just a Dream? 

New hydrothermal and enzymatic digestion plant 

in the PFI engineering lab 

BIoTECHNoLoGY 

New Materials 

and Recycling Methods 

The joint project of PFI Biotechnology Department and 

Kaiserslautern University of Applied Sciences envisages 

that development and selection of special materials 

(cellulose, starch blends, as well as other biopolymers) 

and processing methods will enable all the materials 

used in footwear together with the waste generated 

during production first to be comminuted and 

then merged together. Hydrothermal and enzymatic 

digestion cleave the substances into smaller building 

blocks and the resulting monomers or oligomers can 

be transformed by microorganisms into new starting 

materials such as biopolymers in a fermentation process. 

Any remaining components that cannot be put to 

material use are converted into biomethane (methane 

produced from biomass). The objective is optimum 

utilisation of all the energy and material resources 

present in the footwear materials. Headed by Professor 

Dr.-Ing. Jens Schuster, the Western Palatinate Institute 

of Plastics Engineering (Institut für Kunststofftechnik 

Westpfalz, IKW) on the Pirmasens Campus of Kaiserslautern 

University of Applied Sciences serves as second 

research establishment for the polymeric components 

of footwear. In the course of the project it is intended 

to develop an outsole material which has the rubberyelastic 

properties of a conventional sole material while 

also fulfilling all biodegradability criteria.

THE ECo SHoE - STILL JUST A DREAM? 

Material Database 

Depending upon their field of use in footwear, the 

newly developed materials are tested for their suitability 

for footwear manufacture in the Physical Materials 

Testing Department of PFI. The neighbouring 

ISC subsequently produces sample shoes in close cooperation 

with shoe manufacturers and suppliers to the 

footwear industry. The data collected in the course of 

the research project, concerning, for example, the fermentability 

or the mechanical properties of the biodegradable 

materials, are to be compiled in a database 

and subsequently published. This information provides 

footwear manufacturers with an opportunity to 

increasingly attune their products to ecological needs 

and future regulatory requirements. The knowledge 

gained, together with the database for all materials 

used in footwear production, should open the door 

to ecologically appropriate footwear production by 

making components such as linings, upper materials, 

or adhesives biodegradable. The results of outsole development 

illustrate the huge development potential 

of biodegradable elastic polymers. They also provide 

a basis for further projects focussing on the development 

of ecologically valuable hard-wearing footwear. 

01.2011 


PFI Combines Footwear Competence 

with Biotechnology 

With this project PFI intends to establish a link between 

the original core competence of the organisation, i.e. 

footwear engineering, and the relatively young PFI 

Biotechnology Department, gain further experience 

in the area of biopolymers, and demonstrate practical 

applications of developments ensuing from the on-going 

project concerning production of PHB undertaken 

together with the Johannes Gutenberg University at 

Mainz (Report: Newsletter 1.2010 – pp. 7 et seqq.). 

The research project has already received a favourable 

response. A 2011 project starting date is envisaged. 


Dipl.-Ing. (FH) Christian Schadewell 

Phone: +49 6331 2490 - 843 

E-Mail: christian.schadewell@pfi-germany.de 

15

16 

Newsletter 

Pirmasens Energy Park All Set to Go 

Purchase of a site in the Winzeln industrial zone of Pirmasens 

by PFI has set the scene for practice-oriented 

international research into material and energetic utilisation 

of biomass. 

The Biotechnology Department came into existence 

when PFI moved to the Husterhöhe area of Pirmasens 

in 2003. From the very beginning, research focussed 

on the fast and efficient digestion of biomass. And 

work was by no means limited to production of biogas 

as an energy source; the goal was also to produce 

high-value fermentation products with the aid of biotechnological 

processes. Thus the production of xylose 

from straw and its microbiological transformation into 

xylitol was initially optimised. Other target products 

followed, such as lactic acid and polyhydroxybutyric 

acid (PHB) which can be used for biopolymer production. 

In the course of time it became apparent that 

economic production of energy and raw materials 

from biomass is possible only if the necessary production 

processes performed in decentralised facilities are 

properly matched to one another, thus resulting in 

synergy effects. It is also necessary to intensify the use 

of lignocellulose-containing residual biomass such as 

straw as co-substrate in order to conserve agricultural 

land for food production. 

BIoTECHNoLoGY 

PFI Invests in Pilot Plant 

for Biomass Fermentation 

The scientific and technical basis for practical implementation 

of the idea has been established in various 

individual projects. Thus thermal pressure hydrolysis 

for activated sludge was tested on an industrial scale 

at the Blümelstal sewage plant in Pirmasens and was 

found to increase biogas production by up to 25 percent. 

“Process-controlled enzymatic hydrolysis” (PEH) 

is used to accelerate the degradation of cellulose in an 

agricultural biogas plant at Wallhalben near Pirmasens 

in order to double the throughput of the plant without 

detrimental effects on the process biology. Other 

experimental units for straw digestion were also tested 

in the PFI engineering laboratory. In spite of the success 

of individual projects, it has so far proved impossible 

to integrate all the technical developments accomplished 

by the Biotechnology Department into a single 

practically functioning plant in order to scrutinise the 

expected synergy effects. Such scrutiny should become 

possible and a basis created for further research 

projects and technical developments on construction 

of a demonstration plant. 

The projected fermentation plant is intended to process 

5,000 t of sugar beet, 3,000 t of maize silage, 1,000 

t of straw, and 500 t each of whole-crop cereal silage 

(WCCS) and grass silage per year. Annual production 

of 100 t of xylitol and 400 t PHB is the set goal. In addition, 

the plant will generate 500 kW of electrical energy 

to be fed into the grid and 500 kW of thermal 

energy for the provision of process heat. This corresponds 

to an efficiency of over 80 percent in terms of 

the biomass consumed. On average only about 40 to 

60 percent of the biomass used is currently converted 

into electrical and thermal energy.

PFI INVESTS IN PILoT PLANT 

The following plant components newly developed by 

PFI and its partner organisations will be installed to 

implement the innovative concept: 

Lagoons holding liquid sugar beet silage for 

automatic charging of the fermenters 

Digestion unit for hydrothermal degradation 

of lignocelluloses 

PEH reactor for mixing and liquefying the richly 

structured biomass and acceleration of cellulose 

degradation 

Fixed-bed fermenter for lactic acid production 

and acceleration of the biogas process 

Evaporation unit for concentration of the hydro- 

lysis and fermentation digestates 

Cogeneration unit for energetic utilisation of 

hydrogen-rich biogas 

High-temperature heat pump for generation 

of process heat for the evaporation process 

Digestate processing plant for fixation of 

ammoniacal nitrogen in the fermentation residue 

A central building at the demonstration plant is to 

house a training room and a control centre from which 

the various processes can be controlled and optimised 

under the supervision of engineers and scientists. 

Practical information and training sessions can also be 

offered. The premises will also accommodate members 

of various international research establishments 

working as teams on multi-year research projects. In 

particular, close scientific collaboration in the area of 

biomass utilisation is planned between Rhineland- 

Palatinate and Lorraine. Being so close to France, the 

projected demonstration plant should also help intensify 

collaboration between farmers and companies 

from the two regions. Supporting roles are envisaged 

for agricultural associations and the chambers of industry 

and commerce. Pro-rata funding for the projected 

demonstration plant is expected from the Life+ 

Programme of the European Union. Applications for 

funding of cross-border cooperation between Rhineland-Palatinate 

and Lorraine are to be submitted via 

the Interreg IV programme. 

01.2011 


Now that the plot has been purchased, PFI can proceed 

with permit planning. This will be undertaken in close 

consultation with the City of Pirmasens and Bioenergie 

Pirmasens, a subsidiary of the Pirmasens municipal 

utility company. In total, three plants are planned for 

the Pirmasens Energy Park: a steam gasification unit 

for wood, a methanisation plant for biogenic municipal 

waste, and the above fermentation plant for agricultural 

biomass. Construction of the last-mentioned 

demonstration plant is scheduled to begin in mid- 

2012. 

Silo for maize 

and grass silage 

Straw storage 

Fermentation technology 

and product preparation 

Storage tank 

Straw digestion 

plant 

Projected PFI demonstration plant at the 

Pirmasens-Winzeln energy park 


Dipl.-Ing. (FH) Benjamin Pacan 

Phone: +49 6331 2490 - 840 

E-Mail: benjamin.pacan@pfi-biotechnology.de 

Control center and 

training room 

PEH reactor 

CHP container 

Lagoon for liquid 

sugar beet silage 

Methane 

digester 

Fixed-bed 

fermenter 

17

18 

Newsletter 

In past years PFI has repeatedly initiated EU projects 

related to its core competence of footwear engineering. 

It is no secret that the level of funding in this area 

has meanwhile started to fall owing to the transfer of 

footwear production to Asia. The alternative is to acquire 

EU funding for PFI’s new key research activities 

biotechnology and regenerative energies. To achieve 

this goal the Engineering and Biotechnology Departments 

will be collaborating even more closely. 

Owing to the expected participation of more than six 

countries and bureaucratic hurdles in the application 

phase, many of the funding possibilities set out in the 

7th EU Framework Research Programme require a 

high commitment of human resources. The low success 

rate, which often lies below 15 percent, also poses 

a considerable financial risk for the applicant. In order 

to minimise expenditure of effort and risks, submission 

of applications for transnational projects involving 

only two to three European partners was first considered. 

In response to the current call for proposals, 

a CORNET project on the topic «Upgrading of Waste 

Heat to Process Heat for Different Industries» (for 

short «From Waste Heat to Process Heat») was submitted 

by PFI together with Papiertechnische Stiftung of 

Munich (coordinator), University College of West Flanders, 

Ghent University, Université de Liège, and the 

Flemish User Group. 

BIoTECHNoLoGY 

New EU Project Proposals Submitted 

PFI Expands International 

Research Activities 

CORNET stands for Collective Research Networking, i.e. 

networking of national and regional programmes of 

community research in Europe. The ERA-NET CORNET 

coordinated by the German Federation of Industrial 

Research Associations involves participation of 21 ministries 

and lead partners from 17 countries and regions 

of Europe. The objective is to intensify European coordination 

between national and regional programmes 

of community research. CORNET organises two rounds 

of calls for proposals per year for jointly funded community 

research projects. 

The high-temperature heat pump to be developed in 

this project is an important technical aid for concentration 

of sugar solutions by two-stage vacuum evaporators 

prior to fermentation. In addition, process water 

can also be recovered for straw digestion. Improved 

utilisation of waste heat from the cogeneration unit 

permits use of more straw as substrate for the fermentation 

plant. After determination of the thermal 

energy required for the various sub-processes of the 

innovative biomass processing plants, the PFI Engineering 

Department will develop an intelligent control 

system for heat management in connection with 

the high temperature heat pump. The Biotechnology 

Department will undertake practical tests and develop 

optimisation proposals. The SMEs participating in the 

project (for example, a biogas plant operator) should 

be placed in a position to better utilise the waste heat 

from cogeneration plants. Furthermore, economic aspects 

are to be considered and design parameters determined 

for the use of high temperature heat pumps.

NEW EU-PRoJECT PRoPoSALS SUBMITTED 

In view of the European Union’s aims of raising the 

contribution of renewable energy sources to power 

generation to over 20 percent by 2020 and of doubling 

the current eight to ten percent market share of 

bio-based products by 2020, PFI is expecting a significant 

increase in research funding in these areas in the 

coming years. The nuclear catastrophe at Fukushima 

and increasing oil prices will certainly further boost 

this trend. 

A planned Interreg IV project should serve as an introduction 

to transnational collaboration in the increased 

use of biomass. Here PFI wishes to cooperate with the 

Lorca Agricultural Cooperative, the Lorraine Farmers’ 

Association, and the “Ecole Nationale Supérieure 

d'Agronomie” as well as SMEs in Rhineland-Palatinate 

and Lorraine. The planned project encompasses the 

following tasks: 

Advice on plant cultivation, harvesting, and 

transportation logistics 

Cultivation, supply, and preservation of energy crops 

Construction, operation, and development of 

digestion and fermentation plants 

Optimisation of the fertilising action of digestion 

residues 

Waste Biomass 

Digester 

Xylitol 

as a Sugar Substitute 

Biogas 

Waste Heat 

Residual Biomass 

Electrical 

Energy 

Combined Heat 

and Power Plant 

Engine Cooling System 

High-temperature 

Heat Pump 

Fermentation 

Plant 

Biotechnological 

Conversion 

Projected use of a high-temperature heat pump in a biomass processing plant 

Organisation of information events and seminars 

Exhaust Heat 

Process Heat 

Waste Heat 

Lignocellulosic 

Biomass 

TPH 

Vacuum 

Evaporator 

Hydrolyzate Concentrate 

01.2011 


Biopolymers as Polyhydroxyalkanoates 

(PHA) from Glucose and organic Acids 

The planned transnational research projects should 

provide a basis for further European research activities. 

In the future, PFI plans to submit several project 

proposals yearly in the 7th EU Framework Research 

Programme. Staff members of various European research 

institutions will spend time working at PFI in 

order to establish an appropriate network. A European 

research and development manager will be appointed 

at PFI to coordinate these activities. Small and 

medium-sized enterprises are invited to participate. 

PFI will be glad to help with preparation of the necessary 

project documentation. 


Dipl.-Ing. (FH) Benjamin Pacan 

Phone: +49 6331 2490 - 840 

E-Mail: benjamin.pacan@pfi-biotechnology.de 

19

20 

Newsletter 

Innovative Method for Fitting Shoes 


Fortunately, proper fit has returned to the focus of attention 

of footwear manufacturers, retailers, and customers. 

This interest was rekindled by the results of a 

Germany-wide foot measuring campaign undertaken 

in an AiF research project (the results are to be found 

in a German-language publication entitled “The Foot 

Report” which can be ordered from the address given 

at the end of this article). AiF is the German Association 

of Industrial Research organisations. This study 

showed that properly fitting shoes are hard to find 

by conventional methods of shoe selection. A further 

AiF research project was therefore launched in order 

to develop an innovative and economically practicable 

shoe selection method permitting choice of better 

fitting shoes. 

Cumulative frequency in % 

Fig. 1: 

Level of provision 

of different widths 

for women 

Availability 

of a width 

19% 

4 Widths 

6 Widths 

8 Widths 

Women 

Width according to FAGUS 52 

(Frequency of widths in all sizes) 

RESEARCH 

The foot is a part of the body and by its very nature 

three dimensional. Hitherto, however, selection of 

shoes has been based almost exclusively on shoe size, 

a one-dimensional measure of foot length. The width, 

i.e. a measure of ball girth, is given for only few shoes. 

In addition, no uniform set of tables exists for determining 

the width; instead, there are many tables 

which also differ from one another – albeit only slightly 

in most cases. Most people are unaware of their foot 

width. Of course, customers generally know whether 

they have wide or very narrow feet, if only because 

they have serious problems in finding properly fitting 

shoes. 

In order to supply 90 percent of the population with 

properly fitting shoes, each shoe size would have to 

be available in eight widths. But the costs would be 

prohibitive. If every shoe size were available in four 

widths, then 60 percent of customers could be properly 

provided for (Fig. 1). Yet even then, there would 

still be a substantial risk that shoes would not fit. Additional 

foot measurements should be introduced to 

facilitate correct choice, but that would drive up costs 

out of all proportion. 

Anatomical 

ball circumference 

260 

250 

240 

230 

220 

210 

200 

190 

Anatomical ball circumference 

Women (age dependent) 

15-20 21-30 31-40 

Age group (years) 

51-50 51-60 61-70 

- Sigma Mean value + Sigma 

Fig. 2: Variation of the anatomical ball girths 

of women

WHEN DoES A SHoE FIT? 

Search for Correlations 

Investigations for the new project were undertaken 

on the basis of the foot measurements recorded during 

the foot measuring campaign. To this end, the foot 

measurements were analysed and any correlations 

were sought which could be of value for improved 

shoe selection. Apart from circumference measurements, 

width and height also appeared to be of interest. 

However, these investigations did not lead to any 

useful solution because the measurements showed a 

huge range of variation but no unequivocal correlations. 

The anatomical ball girth, measured over the big 

toe and little toes joints, is mentioned as example: The 

mean value for women was 231.3 mm, but the variation 

was large for all age groups (see Fig. 2). 

In summary, it was concluded that all combinations 

of measurements can occur in feet. No foot types can 

be deduced from the measurements. This finding was 

considered unsatisfactory, especially since different 

foot shapes became apparent on evaluation of the 

measurements, as can be seen in Fig. 3. 

Table 1: Foot types 

Variant Limit of 

heel-instep 

width 

difference 

in mm 

Limit of 

instep-ball 

widht 

difference 

in mm 

Percentage 

of foottype 

A1 

Percentage 

of foottype 

A2 

Percentage 

of foottype 

B1 

01.2011 


Defining Different Foot Shapes 

A different approach to examination of the 

foot measurements was therefore adopted. 

The question posed was: What makes the 

difference between the individual foot 

shapes? The answer lies in the differences 

between the width measurements. These 

obvious differences were therefore studied. 

The measurements used were the maximum 

heel width at 20 percent of the foot length, 

the instep width at 50 percent of the foot 

length, and projected maximum ball width 

(Fig. 4). 

The difference between the individual measurements 

was calculated and the feet assigned to certain foot 

types (see Table 1). Foot types A1, A2, B1, were B2 defined. 

The letter of the alphabet describes the backfoot 

and the numeral the forefoot. Among the female test 

persons, a difference between heel width and instep 

width smaller than or equal to 17 mm classified the foot 

as type A. If the difference was greater than 17 mm, the 

foot corresponded to type B. At a difference between 

the projected ball width and the instep width less than 

or equal to 11 mm, the foot was of type 1; at a difference 

greater than 11 mm the foot was of type 2. 

Percentage 

of foottype 

16_9 16 9 5% 31% 20% 44% 

16_11 16 11 10% 25% 35% 30% 

16_12 16 12 14% 21% 42% 23% 

16_13 16 13 18% 17% 49% 16% 

14_11 14 11 5% 15% 40% 40% 

15_11 15 11 7% 20% 38% 36% 

16_11 16 11 10% 25% 35% 30% 

17_11 17 11 14% 31% 31% 25% 

18_11 18 11 19% 36% 26% 19% 

B2 

Fig. 3: Various foot shapes 

21

22 

Newsletter 

Innovative Method for Fitting Shoes 

This assignment procedure is illustrated by a number 

of examples: 

For a given foot the maximum heel width was 61 mm, 

the maximum instep width 77 mm, and the projected 

ball width 86 mm. The difference between the instep 

width and the heel width is then 77 – 61 = 16 mm, i.e. the 

difference is smaller than 17 mm; the 

backfoot is of type A. 

The difference between the projected 

ball width and the instep width 

is 86 – 77 = 9 mm, i.e. the difference 

is smaller than 11; the forefoot is of 

type 1. The complete foot was classified 

as type A1 (example in Fig. 4). 

In the case of another foot the 

maximum heel width was 64 mm, 

the maximum instep width 88 mm, 

and the projected ball width 104 

mm. The difference between the 

instep width and the heel width is 

then 88 – 64 = 24 mm, i.e. the difference 

is greater than 17 mm; the 

backfoot is of type B (see Fig. 5). 

The difference between the projected ball width and 

the instep width is 104 – 88 = 16 mm, i.e. the difference 

is greater than 11; the forefoot is of type 2. The 

complete foot was classified as type B2 (see Fig. 6). 

These different foot types cannot be obtained by conventional 

grading because the heel would be scaled 

up or down in proportion to the ball measurement. 

RESEARCH 


Fig. 4: 

Test person of 

foot type A1 

Fig. 5: 

Test person of 

foot type B2 

Last Development 

The foot measurements for all shoes sizes were subsequently 

sorted according to these foot types and the 

distribution of the various other foot measurements 

examined in order to be able to assign further measurements 

to these types. On the basis of these results 

the measurements were determined for lasts for closed 

street shoes with a flat toe spring. For sample size 37 

a heel width of 58 mm was assigned to the sole of the 

type A last, and one of 55 mm in the case of the type 

B last. A medium width, width number 5, corresponding 

to a girth of 215 mm was selected for the type A1 

foot, width number 6 (220 mm girth) for types A2 and 

B1, and width number 7 (225 mm girth) for type B2. 

Comparison of the types showed that types A2 and B1 

differed only in the heel width. For the tests a further 

last was produced as a combination of these two. Accordingly, 

type A2B1 differs only in the heel width of 

the last sole, which is 57 mm. The instep height was 

the same for all types at 65 mm. 

The same was done for court shoe lasts, for which 

somewhat different, narrower values were selected 

for the heel width. Type A had a heel width of 54 mm 

and type B a width of 50 mm. The court shoes had a 

heel pitch of 60 mm. No A2B1 combination last was 

made in this case because the more stringent fitting 

demands on this kind of shoe allow no room for compromises. 

Fig. 6: Test person with shoe type B2

WHEN DoES A SHoE FIT? 

Wearing Tests 

The lasts were used to make shoes for wearing tests. 

The feet of the test persons were measured and assigned 

to the corresponding foot type. All the shoes 

were tried on for evaluation, or, in the case of a readily 

recognisable foot type, the appropriate shoe was immediately 

selected. Evaluation was undertaken both 

by the test person and by the person carrying out the 

tests. 

The wearing tests showed that, in addition to the 

width, the fit of the heel is very important. Shoes of 

type B fitted test persons with a slender heel more 

comfortably than those of type A. In contrast, test persons 

with a wide heel felt better in shoes of type A. 

However, the test persons included a number of people 

for whom the available widths did not come into 

question because their feet required an even narrower 

width. Combination of the results of this project and 

greater gradation steps (see final report of AiF Research 

Project 14993) can assure a significantly better 

supply of correctly fitting shoes. 

01.2011 


The detailed results can be found in PFI’s final report 

on AiF Project 15857. The research project was funded 

by the Federal German Ministry of Economics and 

Technology via the German Association of Industrial 

Research Organisations (AiF) in accordance with a resolution 

adopted by the German Parliament. 

Contact: 

Dr. Monika Richter 

PFI Pirmasens e.V. 

Phone: +49 6331 - 249027 

E-Mail: monika.richter@pfi-germany.de 

23

24 

Newsletter 

Joint PFI and LGR Research Project 

The pronounced toxicity of chromium(VI) and the introduction 

of a limit value for chromium(VI) in leather 

articles of daily use have made elucidation of the 

mechanisms of chromium(VI) formation in leather a 

matter of prime concern. In a joint research project, 

the Test and Research Institute Pirmasens (Prüf- und 

Forschungsinstitut Pirmasens, PFI) and the Tanning 

School Leather Institute Reutlingen (Lederinstitut 

Gerberschule Reutlingen, LGR) have investigated 

how total chromium, soluble total chromium, and the 

substances naturally present in hides are interrelated 

with chromium(VI) formation in leather und leather 

goods. 

CHEMISTRY 



Tests for contaminants in footwear and leather goods 

repeatedly reveal the presence of highly hazardous 

chromium(VI). In a recent laboratory study on 

60 shoes of various kinds, some of which contained 

several different kinds of leather, six were found to 

contain high levels of chromium(VI). Among the other 

54 shoes without conspicuous initial chromium(VI) values, 

chromium(VI) could be detected in 11 after they 

had been subjected to an ageing process in which the 

leathers were incubated for 24 hours at 80 °C. The 

German Federal Institute for Risk Assessment had 

long recommended a ban on leather goods with a 

chromium(VI) content exceeding 3 mg/kg. The eighteenth 

amendment to the German Consumer Goods 

Ordinance of 3 August 2010 therefore includes a provision 

for chromium(VI). Consumer goods exceeding 

the chromium(VI) limit value may no longer be placed 

on the market and must be removed from the market. 

This can mean serious economic damage for manufacturers 

and the trade. 

Chromium as Tanning Agent 

Tanning with chromium(III) salts is the principal 

method of leather tanning. Chrome-tanned leather 

is characteristically strong and supple. Its properties 

make it suitable for use in numerous products: for 

footwear and apparel, and also for furniture and 

car interiors. 

What is the Function 

of Chromium in Tanning? 

Leather is a product derived from animal hides preserved 

by tanning. During the tanning process the 

tanning agent chromium binds to the collagen in the

JoINT PFI AND LGR RESEARCH PRoJECT 

The Project and Its objectives 

The complete title of the research project is “Studies to 

Determine the Relations between Soluble Total Chromium 

as well as Hide Constituents and Chromium(VI) 

Formation in Leather and Leather Goods”. It was funded 

as IGF Project No. 15845 N of the Leather Research 

Association (Forschungsvereinigung Leder, FGL) by 

the German Federal Ministry of Economics and Technology 

through the German Federation of Industrial 

Research Associations (AiF) within the IGF programme 

for promoting industrial cooperative research and development. 

The objective of the joint research project undertaken 

by PFI and the Tanning School Leather Institute was to 

elucidate the interrelations between total chromium 

content, soluble total chromium content, the hide 

constituents, and the formation of chromium(VI) and 

to understand the mechanisms involved. 

hides. The leather thus does not shrink; it remains 

supple and retains its strength. The chromium(III) 

salts used in chrome tanning are only very slightly 

toxic since they are only poorly absorbed by the body. 

Chromium(III) can cause local skin irritation in sensitive 

persons. Extremely hazardous chromium(VI) 

can be formed from chromium(III) in reactions favoured 

by oxidation processes and alkaline pH 

values. According to our current state of knowledge, 

chromium(VI), in contrast to chromium(III), 

can penetrate the cell membrane. Chromium(VI) 

is highly toxic, allergenic, and carcinogenic. 

Procedure 

01.2011 


In order to undertake the project, various upper and 

lining leathers were first produced: leathers with high 

and with low chrome tanning agent contents; with and 

without fixation; with various fatting agents; leathers 

of high layer thickness; and leathers with a high 

chromium(VI) content. Total chromium, total soluble 

chromium, and chromium(VI) were measured. What 

information is provided by these measured values? 

Total chromium refers to the total amount of chromium 

present in a leather. Its determination requires 

destruction of the leather by action of acid. 

Total soluble chromium designates that chromium 

fraction of a leather which can be dissolved out of 

the leather by the action of aqueous salt solutions resembling 

human perspiration without destroying the 

leather. This simulates the possible chromium exposure 

of a person that can result on wearing of leather 

products. 

Chromium(VI) is also dissolved out of leather by the 

action of aqueous salt solutions. The difference is that 

only chromium in the +6 oxidation state is determined 

in this case. The principal question is whether the three 

measured values are correlated, and if so, how? Laboratory 

tests for chromium(VI) are generally performed 

prior to or at the beginning of footwear production. It 

was therefore important to include the effects of storage, 

heat, light, and adhesives in the investigations. 

Chrome III 

oxidation 

Reduction 

Simplified representation of transformation 

of chromium(III) into chromium(VI) 

Chrome VI 

25

26 

Newsletter 

Joint PFI and LGR Research Project 

Results for Different Leathers 

Fatting and Amount of Chrome Tanning 

Agent Used 

The choice of fatting agent was crucial for chromium(VI) 

formation during leather production. In contrast, the 

animal hide constituents present in leather have no 

influence on the chromium(VI) values. Use of greater 

quantities of chrome tanning agent led to high contents 

of total chromium and soluble total chromium in 

leather. The amount of soluble total chromium could 

be reduced by fixation of the leather with dicarboxylic 

acids. No correlation could be seen between high total 

chromium contents or high soluble total chromium 

contents and the chromium(VI) content of the leathers. 

Ageing and UV Irradiation 

A considerable influence on chromium(VI) formation 

in leathers could be ascribed to ageing and UV irradiation. 

This is also apparent from studies on the different 

layers of leather. To this end, the leathers were split 

into four layers. The chromium(VI) contents proved to 

be higher in the outer layers directly exposed to the 

environment than in the inner layers. 

CHEMISTRY 



Adhesives and Heat 

Furthermore, the effect of three different adhesives 

on chromium(VI) formation was also examined. Thus 

the leathers were treated with a natural latex adhesive, 

a synthetic latex adhesive, and a PU dispersion 

adhesive. The leathers were additionally subjected to 

heating to simulate the footwear production process. 

Application of adhesive led to significantly higher 

chromium(VI) contents in some of the tested lining 

leathers, whereas upper leathers showed hardly any 

increase in chromium(VI) levels. Adhesive treatment 

and heat tended to slightly reduce the chromium(VI) 

levels in leathers with a high initial chromium(VI) concentration. 

A slight increase in chromium(VI) levels 

was noted in the case of low initial chromium(VI) contents. 

Reducing Agents 

In addition, the effect of reducing agents on the 

chromium(VI) contents of leathers was also investigated, 

both in a vat process and after spray application. 

On the one hand, reducing agents prevent the formation 

of chromium(VI); on the other, they lower the 

concentration of existing chromium(VI). Use of reducing 

agents consistently leads to lower chromium(VI) 

contents of leathers. The reducing action also withstood 

treatment with heat and adhesives. 

Leather lining 

attached to shoe upper

JoINT PFI AND LGR RESEARCH PRoJECT 

The leather was split fourfold 

in order to examine the 

individual layers 

Tests on Footwear 

In addition to the studies on leather samples, items of 

footwear were also produced and the leathers subsequently 

examined in the laboratory. Upper and lining 

leathers with different contents of chrome tanning 

agent were selected for shoe production and two different 

adhesives were used. Four upper leathers and 

four lining leathers were used in one shoe, for the toe, 

the heel, the left side, and the right side, respectively. 

None of the leathers used had a chromium(VI) content 

exceeding 3.0 mg/kg prior to shoe production. In total, 

32 upper leathers and 32 lining leathers from the shoes 

were examined for their chromium(VI) content. None 

of the upper leathers used in the shoes showed increased 

chromium(VI) levels. Five of the lining leathers 

were found to have chromium(VI) values exceeding 3.0 

mg/kg. A long-term test of the shoes over a period of 

three months showed a slight increase of chromium(VI) 

values depending upon the amount of chrome tanning 

agent used. The increased chromium(VI) levels in the 

shoes could be greatly lowered by spray application 

of reducing agents. After a four-week treatment of 

the shoes with reducing agents, the individual leathers 

of the shoes were again examined with regard to 

their chromium(VI) contents. The reducing agent lost 

some of its potential, but the chromium(VI) levels of 

the leathers of the shoes still lay below the legal limit 

value for chromium(VI) of 3.0 mg/kg. 

01.2011 


The findings demonstrate that adoption of specific 

measures can minimise the risk of chromium(VI) formation 

in leather products – in the interests of preventative 

consumer health care. The complete research 

report is available from the contact address. 

Contact: 

Dr. Kerstin Schulte 

Head of Chemical Analysis and Research 

Prüf- und Forschungsinstitut Pirmasens 


66953 Pirmasens 

Phone: +49 6331 2490 712 

Fax: +49 6331 2490 60 

E-Mail: kerstin.schulte@pfi-germany.de 

27

28 

Newsletter 

PFI Participates in Wet-White Round-Robin Test 


and Intermediate Products 

Mould infestation of raw materials and finished products 

repeatedly gives rise to considerable financial 

losses and may also adversely affect the health of employees. 

Such infestation is frequently triggered by a 

high water or moisture content of intermediate products 

that are susceptible to microbial attack and/or 

adverse climatic conditions (rainy season) in the production 

centres of the Far East. For this reason, tests 

for mould resistance of leather intermediate products 

are not only helpful but absolutely essential features 

of quality control. In this way, substandard materials 

can be eliminated and possible infestation and further 

spread of mould can be effectively prevented. 

MICRoBIoLoGY 

Tegewa (an association of manufacturers of textile, 

paper, leather, and fur auxiliaries and colourants, surfactants, 

complexing agents, antimicrobial agents, 

polymeric flocculants, cosmetic raw materials, pharmaceutical 

excipients, and allied products) addresses 

current topics relating to the above areas with the aim 

of offering its members and the market appropriate 

practical solutions. 

Last summer the leather auxiliary section of Tegewa 

set up the “Mould Resistance” Project Group which is 

concerned with questions surrounding this topic. The 

members of the Project Group come from industry and 

from research institutes. 

Over the years, there have been changes in the preservation 

methods used for leather products and intermediates. 

The question thus arises whether the reliable 

yet relatively straightforward laboratory method 

for testing the mould resistance of so-called wet-blue 

(chrome-tanned leather products) published in 1996 

by the above Section is also applicable to wet-white 

(glutaraldehyde-tanned leather products). 

To this end a round-robin test was carried out by five 

participants, including PFI, at the close of 2010.

Round-Robin Test Methodology 

The method is based on an agar diffusion test. Punched 

out specimens are placed with both the flesh side and 

the grain side in contact with an agar plate uniformly 

inoculated with spores of a given test organism and 

incubated at elevated temperature and moisture levels. 

The test organism, a mould fungus, then grows 

initially on the agar and, depending upon the state of 

preservation, possibly also on the specimen. The condition 

of the sample is evaluated on a weekly basis. 

Any inhibition zone appearing around the specimen is 

recorded and measured. 

If there is a lack of mould resistance (evaluation 1/A, A 

= growth area) mould growth generally begins at the 

outer edge and gradually proceeds over the test sample; 

the extent of growth was also measured. 

If preservation is adequate the samples will show no 

mould growth (evaluation 0/0) at the end of the incubation 

period or possibly also an additional zone devoid 

of fungal growth immediately surrounding the 

samples (evaluation 0/H, H = extent of inhibition zone 

in mm) and the material thus fulfils the demands of 

stability toward mould growth over this time interval. 

01.2011 


Test samples, glutaraldehyde tanned „Wet white“ 

Control plates with various test organisms (left to 

right): Aspergillus niger, Penicillium sp., Trichoderma 

viridae, Hormoconis resinae 

a b c d 

Mould formations due to bioburden, outer left on 

untreated samples (a); samples with three different, 

increasing concentrations of an active substance 

(right, b to d) exhibit mould resistance 

29

30 

Newsletter 

PFI Participates in Wet-White Round-Robin Test 


and Intermediate Products 

Round-Robin Test Procedure 

The original method was updated on the basis new 

findings and experience gained by the participants. 

The experts agreed to adopt a number of modifications, 

such as optimisation of the culture conditions 

and prolongation of the incubation time from 21 to 

28 days while retaining weekly evaluation. In addition, 

the range of test organisms was extended to include 

Hormoconis resinae, which can cause material damage 

and is frequently found on leather products. The range 

of test microorganisms thus comprises: Aspergillus sp., 

Penicillium sp., Trichoderma viridae, and the abovementioned 

Hormoconis resinae. Use of a mixture of 

fungal spores (as in the original methods) was categorically 

excluded in the interest of obtaining reproducible 

microbiological results. Determination of the 

Mould resistance towards Penicillium sp. after 

seven days; inhibition zone formation in the case of 

treated samples (b to d) 

MICRoBIoLoGY 

bioburden and internal controls on untreated samples 

were also considered in revision of the procedure. 

Samples for the round-robin test were provided 

by Südleder GmbH & Co. Tests were performed on 

samples without active substance and with four 

different concentrations of the mould inhibitor 

2-(thiocyanomethylthio)benzothiazole (TCMTB). The 

content of active substance was determined at the Research 

Institute for Leather and Plastic Sheeting (Forschungsinstitut 

für Leder und Kunststoffbahnen, FILK), 

which also participated in the round-robin test. 

a b c d a b c d 

Mould resistance towards Aspergillus niger, untreated 

samples are completely covered by mould growth (a) 

and samples with a low degree of preservation only at 

the edges (b). Samples with a higher concentration of 

active substance exhibit adequate mould resistance (c, d).

Results and Conclusion 

A correlation exists between the actual concentration 

of the active compound and the resistance to 

growth of the test microorganisms. Untreated samples 

showed mould infestation after just a few days. Above 

a certain concentration of active substance all the samples 

prove resistant to mould attack, remaining free 

from infestation even after an incubation time of four 

weeks. Some of them even show inhibition zones over 

a period of two weeks, as in the case of Hormoconis 

resinae. Flesh and grain sides show only slight, if any, 

differences. Nevertheless, examination of both sides is 

urgently recommended. 

1/A 

0/0 

Trichoderma viridae 

0% 0,05% 0,1% 0,2% 

Agent concentration (in %) 

Concentration-dependent mould resistance 

towards Trichoderma viridae 

01.2011 


Summarising, it can be stated that the above updated 

method is suitable for testing and evaluating the 

mould growth resistance of wet-white. 

It should, however, be noted that stability to mould infestation 

tested under laboratory conditions does not 

represent an absolute guarantee of mould resistance. 

Additional conventional countermeasures against 

mould infestation are appropriate and advisable. 

The results of the round-robin test were presented 

at the Annual Meeting of the Association for Tanning 

Chemistry and Technology (Verein für Gerberei 

Chemie und Technik, VGCT) at ISC in May 2011. 


Dipl.-Biologin Michaela Würtz 

Phone: +49 6331 2490 550 


7d 

14d 

21d 

28d 

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32 

Newsletter 

Changes to ASTM E2149 Challenge Test Method 

Test Method for Antibacterial 

Activity Updated 

The American standard test method for determination 

of antibacterial activity – ASTM-E2149 – was updated 

at the end of 2010. The procedure is a so-called 

challenge test method which is used in the footwear 

industry, especially for composite materials and complex 

shoe components. 

State-of-the-art materials with an antibacterial finish 

are frequently used in the clothing sector, including 

shoes and shoe components, to minimise the side effects 

and consequences of bacterial attack. 

Shake flask test under dynamic contact conditions Sampling 

MICRoBIoLoGY 

Beyond the shores of the USA, the ASTM E2149 standard 

test method is widely used internationally for determination 

of the antibacterial activity of correspondingly 

finished materials and composite systems, such as 

insoles, in which the active antimicrobial substance is 

immobilised and not subject to diffusion or leaching. 

This test is used particularly frequently by surface finishers 

and developers of antibacterial products and by 

vendors who place goods advertised as having antimicrobial 

properties on the market and wish to perform 

random checks for purposes of quality assurance.

Procedure Widely Used 

in the Footwear Industry 

The advantage of this challenge test method is that it 

can be reproducibly performed in the laboratory, particularly 

on complex composite systems and samples 

that are non-planar or irregularly shaped, as is generally 

the case with footwear components. Moreover, in 

contrast to other test methods, no identical untreated 

control material is necessary to perform testing and 

evaluation of antibacterial activity. These features 

have led to widespread use of the method in the footwear 

industry. 

Plating of the samples for enumeration 

of the viable microorganisms 

01.2011 


In this quantitative method, samples treated with 

antibacterial agents (and where appropriate also untreated 

control materials) are shaken in a bacterial suspension 

with a defined microbial concentration of a 

given test organism, hence the commonly used name 

‘shake-flask test’. The initial microbial concentration is 

first determined. After incubation under dynamic conditions 

for specified periods, the viable bacteria are 

enumerated and the antibacterial activity calculated. 

33

KBE 

1,0E+08 

1,0E+07 

1,0E+06 

1,0E+05 

1,0E+04 

1,0E+03 

1,0E+02 

1,0E+01 

1,0E+00 

34 

Newsletter 

MICRoBIoLoGY 

Changes to ASTM E2149 / Challenge Test Method 

Test Method for Antibacterial 

Activity Updated 

Incubation of the culture medium plates 

Example of a material showing antibacterial 

activity towards Klebsiella pneumoniae 

0h 

1h 

5,0E+05 

2h 

6,9E+04 

3h 

3,3E+06 

4h 

5h 

6h 

7h 

8h 

9h 

10h 

11h 

12h 

13h 

Time 

14h 

15h 

16h 

17h 

Antibacterial Activity Can Also 

Be Expressed in “Log Steps” 

According to the updated version of the test method, 

the antibacterial activity can be stated, as desired, either 

as a percentage reduction of microbial count or as 

the difference of the decadic logarithms, known colloquially 

as ‘log steps’. These are just two different ways 

of expressing the laboratory values determined. 

Depending upon the material, the antibacterial agent, 

and the field of application, differing requirements 

have to be satisfied which need to be agreed between 

the contracting parties. The above standard method is 

used to determine antibacterial activity, not to evaluate 

the results. 

A test for antibacterial efficacy should always include 

independent testing towards a gram-positive and a 

gram-negative bacterium, because the two differ in 

their cell structure. Antibacterial efficacy is assured 

only if there is activity against both groups of bacteria. 

18h 

19h 

20h 

21h 

22h 

23h 

4,2E+07 

24h 1,0E+00 

Material 

Control

Changes Concerning 

the Test organisms 

Changes to the standard concern mainly the test organism. 

In place of the gram-negative test organism 

Klebsiella pneumoniae used in previous versions of the 

standard, the latest version stipulates the closely related 

organism Escherichia coli, which is easier to handle 

in the laboratory. Nevertheless, tests can only be performed 

by trained personnel in a Category 2 microbiological 

safety laboratory because both organisms are 

potential pathogens. 

The failure to specifically address the gram-positive 

bacteria differing in their cell structure in the course of 

the revision process remains a drawback. In the stated 

objective of the revised standard, mention is made of 

its use for a wide range of microorganisms, meaning 

that the use of additional or other microorganisms is 

permissible. 

PFI therefore continues to offer the existing, accredited 

test method with the test organisms Staphylococcus 

aureus (gram-positive bacterium) and either Klebsiella 

pneumoniae or Escherichia coli (gram-negative 

bacterium). 

Although the ASTM E2149 standard test method for 

determining the antibacterial activity of antimicrobial 

treated specimens was updated in 2010, only modest 

changes were actually made. 

01.2011 


Enumeration of viable microorganisms: 

Each colony (spot) corresponds to a viable 

bacterial cell in the original sample 

Participants in a seminar on this and other test methods 

for determining antimicrobial efficacy towards 

bacteria and microfungi, held in late May at the International 

Shoe Competence Center in Pirmasens, were 

able to gain a deeper insight into this topic. 


Diplom Biologin Michaela Würtz 

Phone: +49 6331- 24 90 550 


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36 

Newsletter 

By No Means Trivial 

Shoe Accessory with Core Strength 

Everybody is familiar with them. Everybody uses 

them. Even oetzi, the famous glacier mummy, is considered 

to have been aware of their great advantages 

and every child has to laboriously learn how to tie 

them. We are talking shoelaces. Yet although it is hard 

to imagine everyday life without shoelaces, only few 

people have probably ever asked how they are actually 

made. Since this question has been put to us, we 

would like to provide an insight into shoelace production. 

Shoelace with a 

tubular knitted core 

PHYSICS 

Whether they are called shoelaces, bootlaces, or shoestrings, 

these generally braided or woven textile products 

have long been in use and come in a wide variety 

of shapes and designs: round and flat variants are just 

as common as finely worked laces worthy of wedding 

shoes or coarse and robust laces for doing up work 

boots. 

Sometimes the surface has been treated, sometimes it 

has not. Colour is also of optical importance, with both 

plain coloured and multicoloured laces being present 

on the market. The material used also differs. While 

some laces are made of natural fibres such as cotton, 

others consist of man-made fibres such as polyethylene 

or polyamide, of mixed fibres, or even of leather. 

The structure and material used largely determine the 

properties of the laces.

Which Shoelace 

is Suitable for Which Shoe? 

Or more fittingly: What must a shoelace be able to 

endure and what should it look like? These are in 

fact the principal aspects determining the proper 

choice: 

Since professional, work, safety, or hiking footwear 

has to withstand substantially greater stresses than 

lightweight leisure shoes, the laces clearly have to 

cope with more stringent demands. Here it is recommended 

to use thick, robust, high tensile strength 

laces made of synthetic fibres. Ideally, they should 

also have a round cross section because they can then 

accommodate a core at their centre – as described in 

this article – which enhances their strength. Shoelaces 

made in this way resist abrasion and withstand 

high tensile forces better than flat laces made of 

cotton. Anybody who has tried their hand at mountaineering 

will certainly appreciate the importance 

of strong laces and the security of firmly laced-up 

footgear. 

Casual leisure footwear or seasonal goods which just 

happen to be in fashion are subject to far less stress. 

Imagination knows no bounds with regard to material, 

colour, and production method. Even shoes with 

zip fasteners may have additional laces. Their original 

purpose as a means of closing a shoe no longer 

plays any role. The laces merely serve as decoration. 

The visual appearance and the colour of laces and 

the way in which they are tied have been playing an 

ever-greater role in recent years. There are even web 

pages devoted to the art of lace tying, which present 

a wealth of extraordinary and quirky ways of lacing 

shoes – just try googling “tying shoelaces”! 

01.2011 


In the sports sector, flat, flexible, and extensible 

laces have proved their value for running shoes because 

they are not so stiff as thick round laces. The 

elasticity of such shoelaces also assures a firmer fit 

of the shoes. Moreover, knots in such laces do not 

come undone so quickly. This distinct practical advantage 

predestines the flat variants for use in children’s 

shoes: fewer undone shoelaces mean fewer 

tumbles. 

There can be many reasons for shoelaces coming undone: 

On the one hand, the choice of material plays 

an importance role. If it is fairly rough it will offer 

more resistance to opening of knots and bows. On 

the other hand, the thickness and structure of the 

laces (density of braiding) will have an effect on their 

stiffness. The more inflexible the laces, the easier the 

carefully laced-up shoe will come undone. In addition 

to starting material and method of production, 

substances applied to the material in the course of 

production also play an important role. They may 

influence not only the roughness but also the flexibility 

of the laces. There is currently no standard 

test proceedure for assessing how readily shoelaces 

come undone during wear or which laces have superior 

properties in this respect compared to competing 

products. However, PFI does undertake a test 

to estimate the probability that a knot will come 

undone, paying due attention to structure, stiffness, 

and frictional properties of laces and material. 

On no account should we forget the kind of footwear 

which has to meet particularly stringent demands, 

such as firefighter boots. These have to withstand 

heat and fire and should clearly never catch 

alight. They therefore contain a certain amount of 

fire retardants. 

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38 

Newsletter 

By No Means Trivial 

How a Braided 

Shoelace Is Made 

Shoelaces are produced on braiding machines. Yarns 

supplied for processing first have to be rewound onto 

special bobbins suitable for use on braiding machines. 

The bobbins fully wound with yarn are placed on carriers. 

These are mounted on flyer wheels (Fig. 1) which 

rotate continuously during the braiding process. 

PHYSICS 

Shoe Accessory with Core-Strength 

Fig. 1: Herzog braiding machine with two braiding 

heads and 16 bobbin carriers (source: August Herzog 

Maschinenfabrik GmbH & Co. KG) 

When the braiding machine is set in motion (see Fig. 

2), the bobbin carriers travel – some in a clockwise direction, 

some in an anticlockwise direction – in a serpentine 

fashion from flyer wheel to flyer wheel (cf. 

Fig. 1). On production of round braids and most flat 

braids, these form a circle with the braiding head at 

the centre. This where all the yarns come together to 

form the braid (cf. Fig. 1). While the bobbin carriers 

travel over the flyer wheels they sometimes come close 

to the braiding head and are sometimes more distant. 

In this way the yarns become intertwined to generate 

the visible structure of the braid. 

Fig. 2: Schematic representation of the path of the 

bobbin carriers (red, blue) on flyer wheels arranged 

in a circle

The various colour and structural effects of shoelaces 

are determined by the number and nature of the flyer 

wheels and the yarn, among other factors. Whether 

round or flat braids are produced is also decided at 

this point. 

Round shoelaces have yet another special feature: In 

addition to their visible braiding, forming the sleeve, 

they often have a core concealed in their interior. This 

usually consists of other textile materials. e.g. yarns, 

ply yarns, or tubular knitted material. Core material 

is fed into the machine separately during production 

and is enclosed by a braided sleeve made up of the 

subsequently visible yarns. But why take all the trouble? 

Because the core endows shoelaces with additional 

desired properties: they weigh more, exhibit a 

greater tensile strength, or have better extensibility 

than those without a core. 

The braided cords of several metres length are clearly 

much too long for use as shoelaces. They are therefore 

cut to length. The tips have to be fixed in a plastic 

or metal sheath, known as an aglet, to prevent them 

from unravelling. In the case of synthetic fibres, the 

ends can be welded together ultrasonically to form 

a moulded tip aglet. Alternatively, aglets can be produced 

by crimping a piece of metal onto the shoelace 

or by forming a plastic sleeve directly on the lace. The 

aglets serve not only to protect the tips but also as an 

aid in threading the laces through the eyelets. Oetzi 

can only have dreamed of such convenience! 

01.2011 


Tests 

for Shoelaces at PFI 

PFI offers the following standard tests 

for shoelaces: 

Abrasion (according to DIN EN ISO 22774) 

- laces abrading against each other 

- laces abrading against eyelets 

Tensile strength and elongation 

(based on DIN EN ISO 18691) 

- testing in as-received condition 

- testing after abrasive wear 

Pull-out strength for aglets 

Moreover, PFI can perform other, albeit 

non-standard tests in special cases: 

Water fastness 

Mass per unit length 


Dipl.-Ing. (FH) Kai Tinschert 

Phone: +49 6331 2490 - 16 

E-Mail: kai.tinschert@pfi-germany.de 

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