This study evaluated changes in color of traditional 100% cotton denim and novel cotton/polypropylene denim after 11 different industrial washing processes using various auxiliaries and pumice stone. Color was measured using a spectrophotometer before and after each wash. Significant changes in color parameters L*, a*, b* and total color difference ΔE were observed for both denim types after processes involving bleaching or enzyme + stone washing. The cotton/polypropylene denim showed similar but generally less intense color changes compared to the traditional cotton denim. Processes including bleaching, silicone softener or enzyme + stone washing caused the largest shifts in color.

1. Evaluation of change in color of denim fabric after various
Industrial washing processes with different fiber composition
Mushtaq. Mushtaq Mangat1
, J. Wiener 1
and A. M. Rehan Abbasi1,2
*corresponding author: mushtaq.mangat@gmail.com
Abstract: Traditional denim made by using 100% cotton and novel denim made by using cotton in warp and spun PP
in the weft were treated in 11 different ways on industrial garment washing machines with the help of various textile
auxiliaries and pumice. There is an obvious change in color of denim. This change was measured by using
Spectrophotometer. Reflectance was taken as a variable to observe the intensity of change. Color difference was
measured by using the CIELab color difference formula 1976. Color space coordinates (L*, a*, b*) and color
difference ΔE were calculated between the untreated denim and treated denim.
1. INTRODUCTION
Majority of the denim clothing is passed through a washing process. Primary goal of this
washing is to give a faded look and certain hand feel, which is a key factor in the marketing of
denim clothing [1]. There are a number of methods and textile auxiliaries available to have a
better look and hand feel. The whole process can be divided into three main areas:
1. Desizing and rinsing to remove the sizes applied during weaving
2. Change of color for faded look with the help of bleaching agent and enzymes
3. Application of softener for certain hand feel
The whole process modifies the denim surface since some textile auxiliaries are deposited on the
surface. This modification leads towards the change in the color. Color is a function of the
reflectance and reflectance depends upon the physical and chemical structure of the substance.
Selection of textile auxiliaries and process depends upon the final requirement of the customer.
There is a lack in the evaluation of color changes due to different washing process. The common
practice is to use previous references and hit and trial methods to have required results. In this
study, color changes due to most commonly industrial washing process has been measured with
the help of the spectrophotometer. This technique may help in prediction of the color changes
due to a certain washing process.
There is a drastic change in the physical properties due to industrial washing have been observed.
Most commonly changes have been achieved by using oxidizing agents [2]. Militky and Bajzík
have studied the impact of washing on certain properties of fabric and found significance
changes due to washing [3].
2. METHODOLOGY
1
Technical University of Liberec, Faculty of Textile Engineering; Studentská 2, Liberec 46117, Czech Republic
2
BUITEMS, Department of Textile Engineering, Quetta, Pakistan

2. Two types of denim fabrics were prepared for experiment; one contains cotton as warp yarn and
spun polypropylene weft and other contains cotton in both warp and weft. These two denims
were treated with different textile auxiliaries and stones. However, one sample was kept as
standard to use for the measurement of changes. Detail of denim samples is given in Table 01
and 02. All washings were carried out in a mini clothing washing machine.
Table 1: Traditional and Novel Denim Description
Description Novel Denim Traditional Denim
Warp Yarn Cotton Dyed,
Tex 49.25
Cotton Dyed,
Tex 49.25
Weft Yarn Spun PP
Textile 54.0
Cotton
Tex 49.0
Weave Twill 3/1 Z Twill 3/1 Z
gram per sq. meter (GSM) 234 248
Table 2:Washing processes applied on denim substrate
S# Desized Rinsed Treated
with
Enzymes
Bleached
with H2O2
Application
of Silicone
Softener
Applied
Quick dry
Chemical
Applied
Cationic
Softener
Faded
with
Pumice
Stone
Application
of Water
Repellant
Peached
1W O O
2W O O
3W O O O
4W O O O
5W O O
6W O O O
7W O O O
8W O O O
9W O O O O
10W O O O
11W O O O
All samples were tested in Spectrophotometer (Data Color Spectra flash) using light source D65
and 10° observer. ΔE CIE 1976 L*a*b* equations was used.
(1)
Where

3. 3. RESULTS and DISCUSSION
Table 3 consists of values of the color difference between washed & unwashed denim fabric
specimens.
Table 1 Color difference measurements of washed samples with unwashed sample
Washing
Ref
Washing Detail Novel
Denim
ΔL* Δa* Δb* ΔE Traditional
Denim
ΔL* Δa* Δb* ΔE
W1 Desized and rinsed 1PP -1.44 0.01 0.22 1.45 1COT -2.79 0.60 -1.54 3.24
W2 Desized and treated with
enzymes
2PP -1.17 -0.09 0.24 1.20 2COT -2.38 0.48 -1.67 2.95
W3 Desized, ,treated with
enzymes and bleached
3PP 7.39 0.15 3.67 8.25 3COT 6.07 0.39 2.47 6.57
W4 Desized, bleached and
applied silicone softener
4PP 10.50 0.25 6.10 12.14 4COT 7.42 0.76 4.60 8.76
W5 Desized and bleached 5PP 4.11 0.42 3.07 5.15 5COT 2.02 0.55 2.07 2.94
W6 Desized, bleached and
applied quick dry
auxiliary
6PP 5.02 0.34 4.16 6.53 6COT 1.97 0.46 2.46 3.19
W7 Desized, bleached and
applied cationic softener
7PP 6.90 0.44 3.59 7.79 7COT 5.52 0.44 2.46 6.06
W8 Desized, enzyme and
stone washed
8PP -0.40 -0.05 -0.05 0.41 8COT -2.94 0.06 -0.44 2.97
W9 Desized, bleached,
enzyme and stone washed
9PP 14.89 0.29 5.86 16.00 9COT 11.34 0.66 4.50 12.22
W10 Desized, bleached and
application of water
repellant auxiliary
10PP 4.87 0.47 3.32 5.91 10COT 3.29 0.53 2.27 4.03
W11 Desized, rinsed and
peached
11PP -1.21 0.16 -0.09 1.22 11COT -1.95 0.16 0.22 1.97
Following conclusion can be derived from Table 3:
1. There is a significant change in the color from the standard in all cases.
2. There is a high correlation between novel and traditional denim in L* (0.99) and b* (0.96)
and E (0.93). However, in case of a*, correlation is not strong (0.37).
3. Table 3 depicts that there is a drastic change in ∆E when the sample is desized and treated
with enzymes. Nevertheless, this change is significant when the sample is treated bleached.
4. In most of the cases the trend of change is similar. Only difference is in intensity of change.
There is a significant change in the color from the standard after all washing processes. From the
Figures 1 and 2, it can be observed that W4 (desized, bleached and applied silicone softener) and
W9 (desized, bleached, enzyme and stone washed) made a significant influence compared to
other industrial washes, on the color of both the denim samples regardless their structures.
Samples have shifted much more towards orange hue with increased lightness. This phenomenon
causes a major effect on CIE DE value. It also can be seen that with some washes like W1, W2,
W8 and W11, the change in color is almost negligible.

4. Figure 1: Evaluation of washed Novel denim
samples in Da-Db and DL plans compared to
untreated sample
Figure 2: Evaluation of washed Traditional
denim samples in Da-Db and DL plans
compared to untreated sample
4. CONCLUSION
Two different denims which have been produced by using two different weft yarns show
variation in reflectance after passing through different washing process. CIE Lab parameters and
Δ E were selected to do a comparison. Nevertheless, in case of value a*, there is a significant
difference and correlation is quite low. Furthermore, study concludes that major variation is
linked with bleaching process, whereas, enzyme treatment makes an insignificant changes.
Moreover, stone washing creates moderate variation in color. This work provides a guideline to
denim manufacturers during the finalization of washing process.
References
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pp. 193-199.
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