Abstract laser faded fabrics.In between all tested denim

Abstract

Purpose of this work was to study the effect
of laser denim wash process onto abrasion of seamed denim.  Experimental used a number of three different
weight 100% cotton fabrics,all are indigo dyed, fabricswerefaded using
industrial CO2 laser beam onto seamed areas.  Seams were completed on weft direction for each
tested denim fabric. The three seamed denim fabrics, unwashed and laser faded,
were tested using Rubtester and abraded denim surface was scanned.  Moreover, scanning Electronic Microscopy SEM
for the three fabrics was acquired to explore the difference in surface
morphology, of the laser fading onto different denim fabrics’ weight.Color hue and
?E were detected showing the change in color, throughcomparingunwashed to CO2
laser faded fabrics.In between all tested denim fabrics, resultant data
presentedthe light weight plain weaved denim fabric to be severely damaged by
the fading effect of laser, in terms of abrasion.  For industrial use it is advised to use laser
fading onto heavy weight twill denim garments, and utilize the superimposedseam
instead of topstitched lap-felled seam for anaesthetic durable pieceof laser
faded garment. 

Keywords

Laser types, Seam durability, Denim SEM, Color
Hue

Introduction

Durability of denim garments is expected to be
higher, by consumers, than any other clothing item.   Seam strength is one aspect can be used into
identifying garment’s durability.  Seam
strength is determined through the breaking strength and elongation length of
both a woven fabric and its sewn line. 
Failure at a seam makes a garment unusable even though the fabric may be
in good condition.  There are a number of
possible causes of seam failure; first, the sewing thread wears out before the
fabric does, second, the yarns making up the fabric are broken by the needle
during sewing process, or third, seam slippage occurs (Saville BP 2004).  Abrasion is another aspect predicts the
lasting period of time a garment can endure. 
Fabric quality alone does not fulfil all the criteria for production of
high qualitygarments (Bahere et al. 1997;Dureja 1992).

Sewn seam is the primarily used principal into
assembling a three dimensional garment, by joining each two pieces or edges of
the same piece together.  Sewing is
defined as a two or more pieces of fabric are joined using sewing machines,
sewing threads and various types of stitching (Eberle H et al. 2002).   The simplest seam type of class 1 is formed
by superimposing the edge of one piece of material on another; an example of
this is the French seam which is completed in two stages.  Class 2 of lapped seams is common on jeans;
this provides a very strong seam in garments that will take a lot of wear, though
there is a possibility that the thread on the surface may suffer abrasion in
areas such as inside leg seams (Tyler D. 2005; Carr and Latham 1988).McLoughlin
and Hayes 2013 mentioned that when joining materials aesthetic appeal, strength
and durability are some factors of others should be considered.  Seams should possess durability as much as
the fabric assembled, there are known defects such as seam slippage and seam
pucker mainly shown onto light weight fabrics, not predicted to appear onto
denim garments.  Even though denim wash
process can degrade seamed areas due to the stresses caused by fading chemicals
or mechanical behaviour.

Denim
wash process can be identified as the worn off look of the indigo dyed twill
textile material.  Traditionally is known
as stone and super stone wash; where pumice stones are used in washing machines
with the intended denim garment, achieving the traditional denim washed look
after several hours.  Due to the high
water and time consumption for those washing methods, new technologies have
been applied.  Laser is one of those
technologies with no water wastage.

Laser fading denim is important as it is not a
wet process; precisely controlled faded patterns can be obtained.  Removal of indigo color by laser beam from
denim garments has some recommended waves, ND: YAG laser with wave length
1064nm, or double ND: YAG 532nm.  Also
the clean process of laser beam generated from CO2 at wave length
10600nm (10.6µm).  Excimer laser can be
used for denim fading utilizing wave length in between 196nm to 235nm (Lockman
and Clyson 1996).A research presented by Dascalu et al. 2000 compared between
the ND: YAG laser and CO2 on fading denim; different pulse
parameters were applied, conclusion was made that both CO2and ND:YAG
caused fading; CO2 affected the textile fibers negatively in terms
of strength, due to the heat and evaporation phenomena.  Laser treatments on textile materials are
growing, a recent study by Jiang et al. 2015 the researchers applied an
adhesive to textile fabric, followed by that sticking foil and laser CO2
was applied to give fashionable shades.  A
higher cost might be a result of denim fading process using laser.

A relatively big number of denim fabrics were
tested for laundry effect on pilling and abrasion by Card et al. 2006, denim
samples were pre-washed, stone washed, andcellulase enzyme washed.  Edge abrasion was evaluated atthe bottom cuff
and side seam areas of each sample and rated on scale of four or nodamage to
one or major damage. The samples were examined using either the humaneye or a
stereomicroscope.In conclusion,enzyme treated garments experienced more edge
abrasion than thepre-washed jeans, but less abrasion than the stone washed
jeans after repeatedhome laundering.

Even though, denim wash using various methods,
chemically or mechanically have been used. 
Durability utilising abrasion of laser faded denim various seams was not
investigated before.

Experimental

Three different weights 100% cotton denim
fabrics specified in Table1 were supplied by the Concrete company for
Children’s wear of Egypt, either unwashed and CO2 laser faded fabric
are represented.  Abrading surface of
silicone paper P1500 was used on the machine, the durability of intended seamed
denim fabricswere investigated using abrasion for a constant of 35 rubs of the
Rub-tester BS 5690.  Color hue K/S, which
shows deepness in color, has been examined for all laser treated samples, ? E
was calculated in reference to the control untreated denim sample, using the
Optimatch 3100, ISO105-Jo1:1989.  SEM
using Quanta FEG 250 was done investigating denim surface change due to CO2
laser fading.  

Table1: specification of tested denim fabrics

 

Weight g/m2

Thickness mm

construction

 “FH”

376

0.730

Twill weave

 “FM”

296

0.570

Twill weave

 “FL”

155

0.335

Plain weave

Note: FH Heavy weight fabric, FM is for medium
weight fabric, while FL represents light weight fabric

Laser fading has been done using scan mode
with 500mm/sec speed and interval of 0.1mm, utilizing maximum power 13%. This
was stable for all tested denim fabrics of this study.

Two types of seams were assembled, lap-felled
seam with a double needle topstitch and superimposed seam resembling both inner
and outer side seams respectively, with stitch density of 3.5stitches/cm,
5stitch overlock was used, thread count 40/3 for both seams, while an extra
stitch line lock stitch using thread count 20/2, all threads used were 100%
polyester.

Results and Discussion

Abrasion Test

Table3 shows the different photos of tested
denim fabrics, before and after abrasion for both unwashed and laser faded
effects.  Images show the FL light weight
denim fabric to be severely damaged at seamed areas, causing any constructed
garment from such a fabric to a failure in quality requirements; either in
terms of durability or aesthetic appeal. 
This was the case for both sewn types of seams in table 2 below.  Seams must withstand loads during wearing and
prevent seam breakage or visible damage to the fabric in the seam region
(Mukhopadhyay and Midha 2013).  Form this
context the other two tested fabrics,heavy and medium weight denim, are having
problems in terms of durability when assembled using the lap-felled seam; where
the top stitched lines have been abraded leaving the garment as if worn out.

On the other hand, for superimposed seams of
the heavy weight and medium denim fabrics, showed a better aesthetic appeal
where fading took place but worn out with slippage effect was not present.  This confirms the resultant data of this
research, superimposed seam is a better resolution when garment is laser faded,
either heavy or medium weight.  Even
though, it was mentioned by Ondogan et al. 2005 it would be possible to
transfer certain designs onto the surface of textile material by changing the
dye molecules in the fabric and creating alterations in its color quality by
directing the laser to the material at reduced intensity; light weight denim
plain weave should not be laser faded at seam areas, as shown in this
study.  Any decrease in tensile strength
values indicates damage in fabric structure, laser fading process cause a
decrease in tensile strength values. 
However, the most significant decrease is occurred after 250?s pulse
times. 

Color Hue Test

The
color measurements were carried out between 400-700 nm wavelength and the
values were taken from the wavelength where reflection values were
smallest.  The K/S values of the faded
samples were calculated using the following formula; K/S = (1-R)2 /
(2*R), where R: Reflection value in maximum absorption wavelength, K:
Absorption coefficient and S: Scattering coefficient (Özguney et al.
2009).  The resultant data obtained from
this study is shown in Table2.  Light
weight fabric has the highest change in color after laser fading, this is shown
as from the big ? E value compared to the other heavy and medium weight denim
laser faded ones.  The color change (?E*)
values of the faded samples were calculated by using the following formula ?E*
= (?L*)2+(?a*)2+(?b*)21/2 .

 

FL

FH

FM

? E

10.49

5.72

8.51

 

Before

After

Before

After

Before

After

l

30.42

40.43

23.87

29.36

22.30

30.66

a

1.08

-0.65

1.65

0.55

1.90

0.69

b

-3.78

-6.44

-1.33

-2.49

-2.66

-3.68

K/S

5.942

2.67

10.84

6.67

11.74

5.8395

Table
2: Color Hue and ? E of the three tested denim fabrics before and after laser
fading process

Where a:
Red (+) – Green (-), b: Yellow (+) – Blue (-), L: White (+) – Black (-).

 

 

 

 

Table 3: Surface Morphology of tested denim
fabrics

 

Lap-felled seam for inner denim
pants side seam

 

Unwashed
Before abrasion

Abraded 

CO2
Laser Faded before abrasion

CO2
Laser faded abraded

FH

FM

FL

 

Superimposed seam for outer
denim pants side seam

 

Unwashed
Before abrasion

Abraded 

CO2
Laser Faded before abrasion

CO2
Laser faded abraded

FH

FM

FL

 

 

As
a general rule, if there is a total color difference of ?E equal to 0.2 between
two samples, these samples can be considered visually different (Mercer H
2014).  From table 5 above the “l” value
shows all faded denim fabrics whiter in shade than before CO2 laser
treatment, with highest white effect for the light weight fabric FL.  The “a” value indicates all denim fabrics
with reddish shade prior to laser fading, this was changed to green shade for
the light weight FL denim after CO2 laser treatment, in general all
tested denim fabrics showed less red effect after being laser faded.  The “b” appears to show all examined denim
fabrics with blue shade; again for the light weight FL shade became away for
yellow, as well as the other two heavy FH and medium FM weight CO2
faded denim fabrics.  Lower value of ?E
is shown for the heavy weight FH denim fabric, then medium weight appeared to
get higher differences in shade when CO2 laser faded, finally the
light weight FL is faded intensely when using the CO2 laser fading
technique.

 

Scanning Electronic Microscopy SEM

SEM before and After CO2 Laser
Fading of Different denim weights are shown in table below. Morphology of denim
100% cotton yarns has been studied giving the following scans. Both 150X and
2000X times magnification were observed. 

Table 4: SEM of denim fabrics before and after
CO2 laser fading.

 

 

 

CO2
Laser Faded Denim 150X

CO2
Laser Faded Denim 2000X

FL

FM

FH

Note: FH refers to heavy weight fabric, FM denotes
to medium weight fabric while FL is the light weight fabric.

The
laser action on the colored denim fibers is mainly carried out with the indigo
color, by thermal effect (Özguney et al. 2009). 
This was the reason of the SEM shown for the three tested laser faded
denim fabrics; the thermal effect of CO2 laser invisible beam
attacked the synthetic indigo dye, causing a molten polymer effect shown onto
the burnt cotton dyed warp yarns, this was in line with a former work by Gabr
B. 2016; onto that earlier investigation not only the SEM presented burnt
effect but also air permeability declined for faded 100% cotton indigo dyed
denim fabric.  Photos above show the
effect of laser beam burning effect is minor in case of the heavy weight denim
fabric FH, and a sort of a further scattered burning effect at the FM medium
weight fabric, while almost the entire surface of light weight fabric was burnt
FL. 

Conclusion

In
conclusion, the lap-felled seam is giving a worse effect for the abraded denim
garment, when compared to superimposed seamed lines; not only the indigo dye is
faded but also the topstitched sewing threads are worn off, degrading the
entire garment.  The light weight plain
weaved denim illustrated damage when laser faded, when time passes on the
garment would ruined at seamed areas, giving a low quality piece of garment.On
the other hand, in terms of change in color ?E showed light weight denim fabric
with higher fading effect, which is consistent with the abrasion results and
SEM where the damage occurred due to intense fading.  The findings illustrate the advantage of using
CO2 laser fading technique upon heavy weight to medium denim
fabrics, and the use of superimposed seams to eliminate any damage may be
caused during the laser processing or while in use by denim garment consumer.

Acknowledgement

The
authors would like to thank, Eng. Moustafa Mahmoud Salman and Eng. Ahmed Farouk
managers at Concrete for ready-made garments of Egypt, for supplying materials
and assembled specimens used in this study.

Corresponding
author: [email protected]

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