Effects of water, acids, alkalis and sunlight on the colorfastness of ...

<strong>Effects</strong> <strong>of</strong> <strong>water</strong>, <strong>acids</strong>, <strong>alkalis</strong> <strong>and</strong> <strong>sunlight</strong> on the
colorfastness <strong>of</strong> dyed silk fabrics
by A. Nayeem Faruqui.
Abstract: Improved multi-voltine variety <strong>of</strong> Rajshahi silk fabric was dyed with Reactive Orange 14, Reactive Brown 10, Direct
Orange 31, Direct Yellow 29 <strong>and</strong> Mordant Blue 9 dyes. The effects <strong>of</strong> <strong>water</strong>, <strong>acids</strong>, <strong>alkalis</strong> <strong>and</strong> <strong>sunlight</strong> on the tenacity <strong>and</strong> colorfastness
<strong>of</strong> Rajshahi silk fabric have been investigated. In the cases <strong>of</strong> acid all the dyed fabric shows excellent results but in some
cases <strong>of</strong> <strong>water</strong>, <strong>alkalis</strong> <strong>and</strong> <strong>sunlight</strong> dyed fabric shows unsatisfactory results.
Introduction
Silk has never lost its luxury appeal <strong>and</strong> today all houses in
their top fashion products are showing it. Its characteristics <strong>of</strong>
strength, fineness, <strong>and</strong> length permit more cloth to be made from
one pound <strong>of</strong> silk than any other natural fibre1 . In recent times,
attempts have been made to improve properties <strong>of</strong> silk such as
crease recovery, wash <strong>and</strong> wear properties, anti-photo yellowing,
<strong>water</strong> <strong>and</strong> oil staining resistance, dyeability <strong>and</strong> colorfastness. In
this work, investigation will be made on dyeability <strong>and</strong> colorfastness
properties <strong>of</strong> Rajshahi silk. It is imperative to enhance the
attractiveness <strong>of</strong> the silk fabric by dyeing as well as by improving
its colorfastness. If a textile material is dyed to enhance its pleasing
appearance, the color must withst<strong>and</strong> exposure to light,
weather, moisture washing, etc., for a certain limit. It is also
expected that the dyeing should be level <strong>and</strong> uniform. 2
Some excellent work has been done on solvent effect on dyed
silk in different silk producing countries <strong>of</strong> the world. But in the
case <strong>of</strong> Bangladesh no research which is worth mentioning has so
far been carried out on solvent effects to Rajshahi silk. In the
absence <strong>of</strong> proper research on Rajshahi silk, these luxurious, but
valuable fabrics do not have its good properties, <strong>and</strong> as result
does not attract the attention <strong>of</strong> the buyers. In this research work,
effects <strong>of</strong> <strong>water</strong>, <strong>acids</strong>, alkalies <strong>and</strong> <strong>sunlight</strong> on colorfastness <strong>of</strong>
Rajshahi silk fabric dyed with Reactive Orange 14, Reactive
Brown 10, Direct orange 31, Direct Yellow 29 <strong>and</strong> Mordant Blue
9 have been investigated.
Materials <strong>and</strong> Methods
Materials
As a material for investigations, improved multi-voltine variety
<strong>of</strong> mulberry silk fabric was collected from Bangladesh
Sericulture Research <strong>and</strong> Training Institute (BSR <strong>and</strong> TI),
Rajshahi, Bangladesh. Reagent grade sodium carbonate (99.5%),
sulphuric acid (98%), ammonia solution (25%), sodium hydroxide
(98%); Reactive Orange 14, Direct Yellow 29, Reactive Brown
10, Direct orange 31 <strong>and</strong> Mordant Blue 9 dyes were purchased
from Sigma (USA), Tartaric acid (99.5%) from BDH (Engl<strong>and</strong>)
<strong>and</strong> glacial acetic acid (99.7%) from Merck (Germany), <strong>and</strong>
wheel soap from Uniliver Bangladesh Ltd.
Methods - Degumming <strong>of</strong> Silk fabrics
Silk fabric was degummed by the optimum degumming
method3 . To select optimum dyeing conditions <strong>of</strong> modified silk
fabric, concentration <strong>of</strong> dye <strong>and</strong> electrolyte, dyeing time <strong>and</strong> temperature
were selected accordingly. The percentage <strong>of</strong> dye
absorption was calculated with the spectro-photometric analysis3 .
a. Selection <strong>of</strong> dye concentration: Six dye baths were prepared
with 0.5, 1.0, 1.5, 2.0, 2.5, <strong>and</strong> 3.0% dye on the basis <strong>of</strong>
weight <strong>of</strong> modified silk fabric, <strong>and</strong> the dyeing was carried out
at 85°C for 60 min. The electrolyte concentration was 10%,
<strong>and</strong> the fabric–liquor ratio was 1:50. The concentration <strong>of</strong>
dye that gave the silk fabric even <strong>and</strong> maximum shade was
selected for dyeing.
b. Selection <strong>of</strong> electrolyte concentration: Eight dye baths were
prepared with 0,3,5,7,9,11,13 <strong>and</strong> 15% aluminum sulphate
as electrolyte. The fabric was then dyed with selected concentration
<strong>of</strong> dye, <strong>and</strong> the dyeing temperature <strong>and</strong> fabric–
liquor ratio were same as above. The electrolyte
c.
concentration that gave the maximum absorption <strong>of</strong> dye by
fabric was selected for dyeing.
Selection <strong>of</strong> dyeing time: Seven dye baths, each containing
selected dye concentration <strong>and</strong> electrolyte concentration,
were prepared, <strong>and</strong> the fabric was dyed at varying times as
30, 40, 50, 60, 70 <strong>and</strong> 80 min. The minimum dyeing time at
which the maximum dye absorption was obtained was
selected for dyeing.
d. Selection <strong>of</strong> dyeing temperature: Each <strong>of</strong> seven dye baths
containing selected concentration <strong>of</strong> dye <strong>and</strong> electrolyte was
prepared. Then fabrics were dyed at the selected time by
varying temperature as 50, 60, 70, 80, 90 <strong>and</strong> 100°C. The
lowest temperature at which maximum absorption was
obtained was selected as dyeing temperature.
Calculation <strong>of</strong> the quantities <strong>of</strong> dye & electrolyte
from stock solution
To calculate the quantities <strong>of</strong> dye <strong>and</strong> electrolyte, the following
formula was used4 .
Where W is weight (in grams) <strong>of</strong> fabric sample to be dyed, P
is percentage <strong>of</strong> dye <strong>and</strong> electrolyte to be used (expressed on the
basis <strong>of</strong> the weight <strong>of</strong> fabric) <strong>and</strong> C is Concentration <strong>of</strong> stock solution.
<strong>Effects</strong> <strong>of</strong> <strong>water</strong>, <strong>acids</strong>, alkalies <strong>and</strong> <strong>sunlight</strong> on
the colorfastness test
The colorfastness tests were carried out <strong>of</strong> the dyed silk fabrics
after treatment <strong>of</strong> <strong>water</strong>, <strong>acids</strong>, alkalies <strong>and</strong> after 250 h exposure
under the sun, without protecting from weathering. After
every 50 h, the fastness was assessed by the ‘Grey Scale7 W x P
Stock solution required (mL) =
C
for
assessing change in color’ comparing with the control grade ‘5’.
Results <strong>and</strong> discussion
Dyeing
The fabric was dyed with Reactive Orange 14, Reactive
Brown 10, Direct Yellow 29, Direct Orange 31 <strong>and</strong> Mordant Blue
9. The dye uptake depends on the concentration <strong>of</strong> dye, concentration
<strong>of</strong> electrolyte, dyeing time <strong>and</strong> temperature <strong>of</strong> the dye
bath; therefore, an attempt was made to determine the optimum
dyeing conditions for making the process more economical5 .
<strong>Effects</strong> <strong>of</strong> <strong>water</strong> on dyed silk fabric
<strong>Effects</strong> <strong>of</strong> different conditioned <strong>water</strong> on dyed silk fabric were
investigated <strong>and</strong> summarized in Table-II given on the next page.
Note: The author Nayeem Faruqui can be contacted at Department <strong>of</strong> Textile Engineering, Daffodil International University, 102, Sukrabad, Mirpur
road, Dhanmondi, Dhaka-1207, Bangladesh.
PTJ October 2008 43
Dyeing Printing Finishing

Dyeing Printing Finishing
Dyeing Conditions
In case <strong>of</strong> distilled <strong>water</strong> <strong>and</strong> demineralized <strong>water</strong> there
was no color change. The color <strong>of</strong> dyed silk fabrics become
blackish, when it was immersed in subsoil <strong>and</strong> deep well <strong>water</strong>.
This is because the subsoil <strong>and</strong> deep well <strong>water</strong> contain different
minerals <strong>and</strong> silk fabric readily absorbs the mineral matters
from the <strong>water</strong> <strong>and</strong> becomes discolored (blackish).
On the other h<strong>and</strong> the surface area <strong>and</strong> distilled <strong>water</strong> does
not contain any minerals <strong>and</strong> for this, silk fabric can not absorb
any minerals from the surface or distilled <strong>water</strong> <strong>and</strong> hence no
discolorization is observed.
It is observed from the Table-III that the effects <strong>of</strong> different
<strong>acids</strong> on dyed silk fabric such as sulphuric acid, acetic acid <strong>and</strong>
tartaric acid is excellent for all the cases <strong>of</strong> Reactive Orange 14,
Reactive Brown 10, Direct Orange 31, Direct Yellow 29 <strong>and</strong>
Mordant Blue 9 Dyes.
It is observed from the Table-IV that the effects <strong>of</strong> different
alkalies such as, sodium hydroxide, sodium carbonate <strong>and</strong>
ammonium hydroxide <strong>of</strong> dyed silk fabric are satisfactory in
most <strong>of</strong> the cases but in some cases it give unsatisfactory results
by changing color <strong>and</strong> decreasing the shade.
44 PTJ October 2008
Table-I: Selected optimum dyeing
conditions <strong>of</strong> different dyes
Reactive
Orange
14
Reactive
Brown
10
Used dyes
Direct
Yellow
29
Direct
Orange
31
Mordant
Blue 9
Dye Conc. (%) 1 1 2 2 1.5
Electrolyte Conc. (%) 4 5 7 5 3
Dyeing Time (min.) 60 60 60 60 60
Dyeing Temperature
(%C) 90 80 100 90 100
Water
condition
Subsoil
<strong>water</strong>
Deep well
<strong>water</strong>
Surface
<strong>water</strong>
Deminerali
zed <strong>water</strong>
Distilled
<strong>water</strong>
Table-II: <strong>Effects</strong> <strong>of</strong> various <strong>water</strong> on the
colorfastness <strong>of</strong> dyed silk fabrics
Reactive
Orange 14
(5)
Reactive
Brown 10
(5)
Grade <strong>and</strong> Color
Dyes used
Direct
Yellow 29
(5)
Direct
Orange 31
(5)
Mordant
Blue 9 (5)
Blackish Blackish Blackish Blackish Blackish
Light
Blackish
Light
Blackish
Light
Blackish
Blackish Blackish
4-5 5 4-5 4 4-5
5 5 5 5 5
5 5 5 5 5
Table-III: <strong>Effects</strong> <strong>of</strong> different
<strong>acids</strong> on dyed silk fabrics
Chemicals Dyes used, Color <strong>and</strong> Grade
Unspotted
Sulphuric
acid
Reactive
Orange 14
5 (Bright
Orange)
Reactive
Brown 10
Direct
Yellow 29
5 (Brown) 5 (Bright
Yellow)
Direct
Orange 31
5 (Bright
Orange)
Mordant
Blue 9
5 (Pink)
5 5 5 5 5
Acetic acid 5 5 5 5
Tartaric
acid
(Shade
increase)
5 5 5 5 5
It is evident from the table that sodium hydroxide <strong>and</strong>
sodium carbonate are more effective to change in color than
ammonium hydroxide. Mordant Blue 9 to sodium hydroxide
<strong>and</strong> Sodium carbonate spotting give blue color.
From the Table-V, it is seen that the silk fabric dyed with
Reactive Orange 14, Direct Orange 31 <strong>and</strong> Direct Yellow 29
exhibits considerably better colorfastness on exposure to <strong>sunlight</strong>
in air than other dyes used in the present investigations.
Reactive Brown 10 <strong>and</strong> Mordant Blue 9 showed poor colorfastness
to <strong>sunlight</strong>.
Dyestuffs do not possess the same degree <strong>of</strong> fastness to
light on silk <strong>and</strong> this may be due to one or more important factors.
One factor that certainly has an important bearing on the
light fastness <strong>of</strong> various dyestuffs on silk fabric is the change in
color <strong>of</strong> dyed silk on exposure to light.
The colorfastness <strong>of</strong> dyed fabric depends on the physical
<strong>and</strong> chemical properties <strong>of</strong> the fabrics, the class <strong>of</strong> the dyes <strong>and</strong>
their forces <strong>of</strong> interaction; the intensity <strong>of</strong> light <strong>and</strong> many other
factors.
Chemicals
Unspotted
Sodium
hydroxide
Sodium
carbonate
Ammonium
hydroxide
Table-IV: <strong>Effects</strong> <strong>of</strong> different
<strong>alkalis</strong> on dyed silk fabrics
Reactive
Orange
14
5
(Bright
Orange)
Dyes used, Color <strong>and</strong> Grade
Reactive
Brown 10
5
(Brown)
Direct
Yellow 29
3 3 3-4
5
(Shade
increase)
5
4
(Shade
decrease)
5
(Shade
increase)
Direct
Orange
31
5 5
(Bright (Bright
Yellow) Orange)
4
3
(Shade
decrease)
4
(Shade
decrease)
Mordant
Blue 9
5
(Pink)
Blue
Blue
5 5 5

It is also observed from the Table-V, that the change in color
<strong>of</strong> dyed fabric occurs abruptly within 50-100 hours exposure
<strong>and</strong> then no or slight change occurs on further increase <strong>of</strong>
exposure time. This is, possibly, due to the mechanism <strong>of</strong> the
light action produced by the dye on the fabric.
An intensive oxidation <strong>of</strong> the fabric is due to the capacity <strong>of</strong>
the molecule, exited by the absorption <strong>of</strong> the short wave or
UV-light to be reduced because <strong>of</strong> the NH2 group (amino
<strong>acids</strong>) contained in silk.
As a result, the glycidyl radicals formed in silk fibroin by the
irradiation immediately react with atmospheric oxygen <strong>and</strong>
changes to peroxy radicals. This oxidation reaction occurs at
the earlier time <strong>of</strong> light exposure. After completion <strong>of</strong> the reaction
the change in color or fading does not occur rapidly6 .
Conclusion
The effect <strong>of</strong> in subsoil <strong>and</strong> deep well <strong>water</strong> on the dyed
Rajshahi silk fabric is remarkable <strong>and</strong> the color <strong>of</strong> dyed silk has
been changed by the absorption <strong>of</strong> minerals from the <strong>water</strong>.
But in the case <strong>of</strong> demineralized <strong>water</strong> <strong>and</strong> distilled <strong>water</strong> the
dyed fabric exhibits its original color.
In the case <strong>of</strong> acid, the fabric exhibits good colorfastness
after spotting with acid. Spotting with alkalies, e.g., sodium
hydroxide <strong>and</strong> sodium carbonate were more reactive with dyed
silk fabric than ammonium hydroxide.
After exposure to <strong>sunlight</strong> in air the silk fabric dyed with
Reactive Orange 14, Direct Orange 31 <strong>and</strong> Direct Yellow 29
exhibits considerably better color than Reactive Brown 10 <strong>and</strong>
Mordant Blue 9. Considering all the effect it was seen that dyed
silk fabric withst<strong>and</strong>s their color in demineralized <strong>water</strong> <strong>and</strong> distilled
<strong>water</strong>.
References
1. Hess, K. P. (1978); Textile Fibres <strong>and</strong> their uses (6 th edition),
Oxford <strong>and</strong> IBH Publishing Co., New Delhi, p.157-159, 222
- 248.
Further cementing their technologically
leading position in the Bangladeshi
textile processing industry, Chaity
Composite Ltd. has placed an order for
three THEN-AIRFLOW ® SYNERGY 1500
machines, complete with THEN’s dyehouse
management solution <strong>and</strong> a chemicals
dispensing system.
Highlighting the economic <strong>and</strong> ecological
benefits this investment, Chaity
Group’s Managing Director, Mr. Md. Abul
Kalam says: “Our acquisition <strong>of</strong> THEN-
AIRFLOW machines will provide us with
the lowest <strong>water</strong>, chemicals <strong>and</strong> energy
consumption in the industry <strong>and</strong> thus with
the most competitive operating costs.
Moreover, our high-pr<strong>of</strong>ile buyers are
dem<strong>and</strong>ing an increasingly better performance
in ecological terms, such as
<strong>water</strong> conservation <strong>and</strong> minimum effluent
discharge. We can now guarantee this for
the foreseeable future with our new
THEN-AIRFLOW .”
Table-V: Effect <strong>of</strong> <strong>sunlight</strong> on dyed silk fabric
Exposure
period (hr)
00
Reactive
Orange
14
5
(Orange)
Fastness Grade <strong>and</strong> Color
Reactive
Brown 10
Direct
Yellow 29
5
(Brown) 5 (Yellow)
Direct
Orange
31
Mordant
Blue 9
5
(Orange) 5 (Pink)
50 5 4-5 4-5 5 5
100 4-5 4 4-5 5 4-5
150 4-5 3-4 4-5 4-5 4
200 4-5 3-4 4 4-5 4
250 4-5 3 4 4 3-4
2. Cockett, S. R. <strong>and</strong> Hilton, K. A. (1961); Dyeing <strong>of</strong> cellulosic
fabric <strong>and</strong> related processes, Leonard Hill (Books) Ltd.,
London, p. 31-36.
3. Charles, H. G. (1974); A Laboratory course in dyeing, 3 rd ed.,
the Society o f Dyers <strong>and</strong> Colorists, Bradford Yorkshire,
Engl<strong>and</strong>, pp. 54-58, 79.
4. Grey Scale for assessing change in color - (International
St<strong>and</strong>ard, British St<strong>and</strong>ards Institution).
5. International St<strong>and</strong>ard Organization, 5081-1977 (E), Textile-
Woven Fabrics. Determination <strong>of</strong> breaking strength <strong>and</strong>
elongation (Strip Method).
6. Sadov.F. Korchagin,M. Matetshy, A. Chemical technology <strong>of</strong>
fibrous materials. Mir Publishers, Moscow, 1973. PP.97-108,
294-99, 315-38, 364-89, 394-96,417-18,434-36,455-
57,486-504.�
Major company in Bangladesh selects THEN-AIRFLOW®
From left: Mr. Wilhelm Eickh<strong>of</strong>f, Area Sales
Manager <strong>of</strong> THEN Machinen GmbH, Mr. Md. Abul
Kalam, Managing Director <strong>of</strong> Chaity Group <strong>and</strong>
Mr. Thomas Archner, CEO <strong>of</strong> THEN Maschinen
GmbH.
The newly ordered machines will be
set up at Chaity Composite’s dyehouse in
Narayangonj.
THEN Maschinen GmbH
THEN-Maschinen GmbH is the technology
leader in piece dyeing. Its patented
THEN-AIRFLOW technology introduced
some 25 years ago enables a true ULLR
(ultra-low liquor ratio) <strong>of</strong> 1:3.5 with cotton
knit fabrics – including fabric pick-up <strong>and</strong>
free liquor. Some 2,000 THEN-AIRFLOW
units are in operation world-wide.
As higher awareness <strong>of</strong> limited <strong>water</strong>
<strong>and</strong> energy resources is spreading around
the globe rapidly, dem<strong>and</strong> for THEN-AIR-
FLOW technology is significantly shifting
beyond traditional European <strong>and</strong>
American markets towards Asia <strong>and</strong> the
Indian sub-continent. THEN Maschinen
GmbH is a member <strong>of</strong> the Fong’s Group.�
PTJ October 2008 45
Dyeing Printing Finishing