How to Determine Color Fastness to Wash

Color fastness to wash:

Color fastness to wash is the resistance of a material to change in any of its color characteristics as result of washing with household detergent. Colorfastness to washing is very important for Lab-dip in dyeing factory. It is one of the most important and mostly used colorfastness test. There are varieties of testing procedure, because:

1. Washing conditions may vary from one country to another.
2. To evaluate repeated washing accelerated test methods are used.
3. The methods on the use of dyed goods.

The accelerated washing tests are designed for evaluating the color fastness to washing of textile, which are expected to withstand frequent washing. The color loss and surface changes resulting from detergent solution.

Principle:
Specimens are tested under appropriate conditions of temperature, detergent solution, bleaching and abrasive action such that the color change is similar to that occurring in five hand, home or commercial launderings

Procedure:
A test specimen measuring 10 X 4 cm of the material to be tested is cut out. Yarn is knitted into a fabric from which a piece of the same dimensions can be obtained. The specimen to be tested is placed between two pieces of undyed fabric measuring 10 X 4 cm anf the three pieces are held together by stitching round the edges. In the case of loose fiber the compressed mass is held in place by sewing it between pieces of cloth measuring 10 X 4cm. The composition of one the colorless materials enclosing the specimen will be the same as the dyed sample and the other will be as indicated below:

A solution is made containing 5 gpl of soap in which free alkali calculated as Na2CO3 should not be more than 0.3% free alkali calculated as NaOH should not be more than 0.1% and total fatty matter should not be more than 85%.

Washing test 1006 CO1 (ISO 1):
The composite specimen is tested in a Standard Wash Wheel/Wash Fastness tester at 40+2° C for 30 minutes using a liquor ratio 50:1.

Washing test 1006 (CO 2):
The composite specimen is treated in the same wash wheel in the above soap solution for 45 minutes at 50±2°C using a liquor ratio 50:1.

Washing test 1006 CO3 (ISO 3):
The composite specimen is treated in the same wheel in the above soap solution in the presence of another 2 gpl anhydrous sodium carbonate at 60±2°C for 30 minutes using the same liquor ratio.

For all of the above cases the treated samples are rinsed which in cold water distilled water following 10 minutes rinsing in cold running tap water. After squeezing the stitching is removed on the two long sides and the other two short sides. The pieces are opened out and dried in air at a temperature not above 60°C. the change in color of the uncovered portion of the specimen is assessed with Gray Scale No. 1 and the staining of the undyed materials with Gray Scale No. 2.

Washing Test 1006 CO4 (ISO 4):
The dyed specimen measuring 10 X 4 cm as before is sewn together with two pieces measuring 5 X 4 cm. One piece is the same material as before:

The specimen is treated in soap solution mentioned in the previous test at 95±2° C for 30 minutes using the same liquor ratio.

Washing test 1006 CO5 (ISO 5):
The composite sample is prepared as in the previous cases with the exception that .

The test specimen is treated in the soap solution mentioned in the ISO 3 test. But treatment is carried out 95±2°C for 4 hours suing a liquor ratio 50:1. The rinsing, drying and fastness assessment is same as mentioned earlier.