Color fastness .pdf

Textile color fastness

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Textile Testing & Quality Control-II
.

Color Fastness

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Color fastness is the resistance of the color to fading or
bleeding by different agencies like washing, light,
Water, dry cleaning, perspiration, ironing, acid, alkali
etc.
Color fastness is usually assessed separately with
respect to:
1.Changes in the color of the specimen being tested,
that is color fading
2.Staining of undyed material which is in contact with
the specimen during the test, that is bleeding of color.
Color Fastness

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A dyed or printed material may loose its color due to
the following causes-

Decomposition of the dye molecules in the fibers (light
fading)
Removal of dye molecule into the external medium
(washing)
Friction on the outer surface of the dyed materials
(rubbing)
Reaction with acid, alkali or perspiration (perspiration
Color Fastness

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Different Types of Color Fastness
Color Fastness to Wash
Color Fastness to Light
Color Fastness to Rubbing/Crocking
Color Fastness to Perspiration (Acid/Alkali)
Color Fastness to Saliva
Color Fastness to Water (Hot)
Color Fastness to Water (Cold)
Color Fastness to Sea Water
Color Fastness to Chlorinated Water
Color Fastness to Bleaching (H
2
O
2
/ Hypochlorite)
Color Fastness to Alkali/Acid Spotting
Color Fastness to Dry Cleaning
Color Fastness to Hot Pressing

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Factors affecting the color fastness properties
The molecular structure (e.g. size) of a dye molecule.

The manner in which the dye is bonded to the fiber (i.e. the dye-fiber bond

The amount of dye present in the fiber, i.e. depth of the shade.

The chemical nature of fiber.

The presence of other chemicals in the materials such as softener, binder,
additives etc.

The actual conditions prevailing during exposure.

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Effect of shade % on light fastness

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Assessment of Color Fastness:
Changes in the color of the specimen being tested, that is color
fading;

Staining of undyed material which is in contact with the
specimen during the test, i.e. bleeding of color.

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Color change grey scales
These scales consist of five pairs of grey colored material
numbered from 1 to 5.
Number 5 grey scale has two identical greys (no contrast),
number 1 grey scale shows the greatest contrast,
and numbers 2, 3 and 4 have intermediate contrasts.
After appropriate treatment the specimen is compared with
the original untreated material and any loss in color is graded
with reference to the grey scale. When there is no change in
the color of a test specimen it would be classified as ‘5’; if
there is a change then it is classified with the number of the
scale that shows the same contrast as that between the
treated and untreated specimens.

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Degree of staining grey scales
A different set of grey scales is used for measuring staining.
Fastness rating 5 is shown by two identical white samples (that is no
staining) and rating 1 shows a white and a grey sample. The other
numbers show geometrical steps of contrast between white and
series of greys. A piece of untreated, unstained , undyed cloth is
compared with the treated sample that has been in contact with
the test specimen during the staining test and a numerical
assessment of staining is given.
A rating of 5 means that there is no difference between the treated
and untreated material.
If the result is in between any two of the contrasts on the scale, a
rating of, for example, 3-4 is given.
Sets of grey scales, examples of which are shown in Fig(in next slide)

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Instruments for the Assessment of Color Fastness
1. Visual Assessment

Color change grey scales.

Degree of staining grey scales.

11. Color Change Grey Scale
11

12. Degree of staining grey scales
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13. Degree of staining grey scales
13

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Multiple strip
Multifiber DW Multifiber TV
Secondary acetate Triacetate
Bleached cotton Bleached cotton
Polyamide Polyamide
Polyester Polyester
Acrylic Acrylic
Wool Viscose

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Grey Scale Rating
Fastness GradeShade Change of
Tested Sample
Colour
Fastness of the
Sample
Staining condition
of the white cotton
cloth
Grade-5 No Change Excellent No Staining
Grade-4 Slight loss in DepthGood Very Slight Staining
Grade-3 Appreciable loss in
depth
Fair Moderate Staining
Grade-2 Significant loss in
Depth
poor Significant Staining
Grade-1 Great Loss in DepthVery Poor Deep Staining

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Test standards
Society of Dyers and Colourists (SDC)
American Association of Textile Chemists and Colorists (AATCC).
International Organisation for Standardisation (ISO)
International Wool Textile Organisation (IWTO).
British Standard (BS)

American Society for Testing & Materials (ASTM)

Australian Standard (AS)

Japanese Industrial Standard (JIS)

(Deutsches)German Institute for standardization (Norm) (DIN)

Swiss Norm (SN)

Bangladesh Standard & Testing Institution (BSTI)

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Color Fastness to Washing
The resistance to the loss of the color of any dyed or printed material in
washing is referred to as its wash fastness.

Poor wash fastness properties is due to

If dye materials have not penetrated inside the inter polymer chain space of
fiber or

have not attached to the fiber with strong attractive force

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•The variety of washing methods available,

•Washing condition varies from one country to another,

•When material being washed,

•End use of the product,

•The development of detergents and bleaches.

Varieties of test methods

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Soaps and detergents
Most detergents contain mild oxidising agents, softeners, optical brightening agents,
salts

Oxidising agents cause degradation of the dye molecules.

The dispersing nature of different detergents can also reduce the level of
cross-staining to an adjacent fabric
ECE Non Phosphate Detergent A

IEC Non Phosphate Detergent A

ECE Phosphate Reference Detergent B

IEC Phosphate Reference Detergent B

Sodium Perborate Tetrahydrate

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Test Specimen
Sample size:10cm X 4cm
Sample preparation

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Where yarn or loose fiber is to be tested, a mass of the yarn or loose fibre
approximately equal to one-half of the combined mass the adjacent fabrics
is taken. Then is placed between a 10 cm X 4 cm piece of the multifiber
adjacent fabric and a 10 cm X 4 cm piece of non-dyeable fabric and sew
them along all four sides.

Yarn & Fibre:

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ISO Wash Fastness test Condition
Test
Method
Temp.
(
0
C)
Time
(min)
M:LNo. of
Steel
Balls
Chemicals
Reproduce Action
of
ISO
105-C01
40±2 30
1:50
0 Soap Hand Washing
ISO
105-C02
50±2 45
1:50
0 Soap
Repeated Hand
Washing
ISO
105-C03
60±2 30
1:50
0
Soap
+Na
2
CO
3

Medium Cellulosic
Wash
Severe Wool Wash
ISO
105-C04
95±2 30
1:50
10
Soap+
Na
2
CO
3

Severe Cellulosic
Wash
ISO
105-C05
95±2 240
1:50
10
Soap+
Na
2
CO
3

Very Severe
Cellulosic Wash

23. Determination of color fastness of a fabric to washing
•For determining color fastness of a fabric to washing, the
fabric is washed with detergent usually along with an
undyed fabric. Then color fastness is assessed separately
with respect to:
•Changes in the color of the sample tested (that is color
fading) and
•Straining of the undyed fabric which is in contact with
the specimen during the test (that is bleeding of color)
•Instruments required:
•1. Rotawash/Gyrowash
2. Stainless steel balls
3. Multi-fiber fabric
4. Grey Scales
5. Sewing machine

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24. •Recipe: Sodium Perborate …….1gm/litre
ECE Phosphate…………...4gm/litre

Sample (specimen) size:
•Sample Fabric : 10cm x 4cm
Multi-fiber fabric: 10cm x 4cm
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25. Procedure:

•1. Fabric is usually tested in the form of a composite
specimen, made up of the test specimen placed in the contact
with undyed fabric usually in the form of multi-fiber strip, of
the same size. For this, the sample fabric is sewed with the
multi-fiber strip.
2. Solution is prepared according to recipe.
3. The composite specimen, solution and 25 steel balls are
placed in the washing pot, which is then closed with a lid.
4. The pot is placed in the bath of Gyrowash/Rotawash and
the bath is heated up to 40°c.
5. The specimen is treated with detergent for 30 minutes with
a rotational movement of the pot and taken out after 30
minutes.
6. The specimen is (first )rinsed (with hot water and then)with
cold water and then dried in oven at 60°c.
7. The fabric sample and the multi-fiber fabric are separated.
The fabric is assessed for color fading and multi-fiber fabric is
assessed for staining with the help of color change grey scales
and degree of staining grey scales.

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1. Color Change
Assessment of Wash Fastness
Before Washing After Washing
2. Color Staining
Before Washing After Washing

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Color fastness to rubbing ISO 105 X12
Evaluate the transfer of colorant from the surface of a colored fabric to another
surface or to an adjacent area of the same fabric when it is applied to surface
friction or rubbed against a rough surface.
Two types of tests are normally done-

Dry rubbing test

Wet rubbing test

The tests are done at 20
0
C±2
0
C and
Relative humidity 65%±2%.

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The crocking cloth against which the test sample will be rubbed is a white, bleached,
but without finished and undyed cotton fabric.

For wet rubbing test, this cloth is wetted with distilled water and to keep 100% pick
up, excess water is removed by blotting paper

The size of these fabrics is 5 cm x 5 cm. This is an ISO recommended fabric.
Fig: Crock meter
Crocking Cloth

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Cut the sample as long as that can cover the metallic mounting plate
(standard size 14 cm x 5 cm).

Two test specimens are required for dry rub and two for wet rub.

For dry rub test, one specimen will be placed to warp direction and the other
to weft direction.

For wet test, two samples were placed similarly.

Then the test specimen is rubbed to and fro (10 x 10 rub, 1 rub/sec) by
means of crock meter finger.

Fabric sample Preparation:

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•Compare the contrast between untreated and treated white crocking cloth
with the staining grey scale.

•Again, color contrasts of rubbed and unrubbed dyed samples are compared
with colour change grey scale.

For both types of rubbing test, the fastness is rated from 1 to 5, where 1
means the worst rubbing fastness and 5 means excellent rubbing fastness.
Evolution:

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Color Fastness to Perspiration
ISO 105 E04:1993
The garments which come into contact with the body and where perspiration
is heavy (like neck, under arm etc), may suffer local discolouration.

Fastness to perspiration is the resistance of color of textile against the
discolouration effect of textile against acidic or alkaline perspiration.

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Name of the Chemical Acid Alkaline
l- Histadine mono-hydrochloridemono-hydrate
(C
6
H
9
O
2
N
3
HCl.H
2
O)
0.5 gm 0.5 gm
Sodium chloride (NaCl) 5 gm 5gm
Sodium hydrogen orthophosphate dehydrate
(Na
2
HPO
4
.2H
2
O)
2.5 gm 2.2 gm
Distilled water 1000 ml 1000 ml
PH 8 5.5
Reagent for Preparation of Artificial Perspiration

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Wet out the composite test specimen in mentioned perspiration solution
separately at room temperature, liquor ratio 50:1and kept for 30 minutes.

Pour off excess solution and place this composite test specimen between
two glasses or acrylic plates under a pressure of 12.5kPa and then place in
an oven for 4 hr at 37± 2
0
C.

Remove the specimen & hank to dry in warm air not exceeding 60
0
C.

Don’t press or iron the specimen or the multifibre test fabric.

Test Procedure

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Colour Fastness to Light
Light fastness test measures the resistances to fading of dyed textile
maaterial when exposed to sunlight.

Exposure to sunlight is a test of the behavior of the sample under actual
condition of use, but it takes long time.

The test specimen is exposed for a certain time (12h, 20h, 24h, 36h, 72h etc
or as customer demand) under the light and compared the changes with the
original unexposed specimen.

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Spectral composition of light from the source, especially the
amount of ultra violate light present.

The temperature & humidity of the air in contact with the
sample.

Presence of any residual chlorine in the fiber.

Chemical in the surrounding air during testing.

The rate of fading on exposure of a dyeing is sensitive to-

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Daylight B01

Xenon Arc B02

Mercury-Tungsten fluorescent lamp (MBTF) etc.

Light sources may use-

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Description of the light Fastness grades
Fastness GradeDegree of fading Light Fastness
Grade- 8 None Outstanding
Grade- 7 Very, very slight Excellent
Grade- 6 Slight Very Good
Grade- 5 Moderate Good
Grade- 4 Appreciable Moderate
Grade- 3 Significant Fair
Grade- 2 Extensive Poor
Grade- 1 Very extensive Very Poor

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