Color Fastness Test | Washing Fastness Test | Washing Fastness | Color Fastness to Washing

The property of a dye to retain its color when the dyed (or printed) textile material is exposed to conditions or agents such as light, perspiration, atmospheric gases, or washing that can remove or destroy the color. A dye may be reasonably fast to one agent and only moderately fast to another. Degree of fastness of color is tested by standard procedures. Textile materials often must meet certain fastness specifications for a particular use.

It is always useful and interesting to test the dye which is to be used on a sample of the yarn or fabric to be dyed. The outcome will depend on the fabric, the mordant that has been used and dye that has have been chosen. Testing is best carried out on a series of Groundnuts marked (for identification) samples, which have been mordanted with a number of different mordants. Tests can be carried out for light, water and washing fastness using simple standard test methods.

To Test for Washing Fastness Follow these Steps :

• Take two pieces of fabric about 5cm by 5cm, one of which is undyed cotton and the other undyed wool. Stitch them together along one side.
• Take some sample strips of the dyed yarn and spread them evenly between the two pieces of cloth so that they overlap both sides. If dyed fibre is being tested a combed sample can be used in place of the yarn.
• Sew around all four sides of the cloth so that the yarn is held in place.
• Prepare a similar specimen with dyed materials that has satisfactory properties and place them in two jars with screw lids containing a solution of 5gm per litre soap or detergent solution at 30oC.
• Agitate the two jars gently for 30mins, then remove the fabrics and wash them gently in clean water for 5mins. Open the stitching and separate the pieces to dry in air. Examination:
• Place the dyed yarn next to a sample of the same material which has not been tested, and compare the change which has taken place. Compare also with the control sample with satisfactory properties. If the dyeing being tested shows equal or less change than the satisfactory sample, then it is as good as the satisfactory sample.
• Place the wool and cotton cloths next to samples of the same material which have not been tested and compare them with the cloths that have been tested with a satisfactory dyeing. Equal or less staining shows equal or better fastness.

Washing Fastness Test | Wash Fastness | Description of Washing Fastness | Types of Washing Fastness

Color Fastness:

Color fastness is the ability of fabrics to retain the dyes used to color them. Some fabrics hold dye within their fibers extremely well - like denim - while others do not (mostly synthetic or artificial non-natural fabrics) and tend to “bleed” when they are washed. The denim would therefore be more “color fast” than the other fabric.

The resistance of a material to change in any of its color characteristics, when subjected to washing is called color fasntess to washing.

General Principle:
A specimen of the textile to be tested, with the adjacent fabric attached is subjected to washing under specifiend conditions. Te extent of any change in color and that of the staining of the adjacent fabric are assessed and the rating is expressed in fastness numbers.

There are two types of adjacent fabrics; (1) single fibre fabric and multiple fibre fabric. In the case of multifiber fabric only one specimen is required and in the of single fiber fabric two adjacent faabric are required.

There are various colorfastness tests. Details of washing fastness tests are given below.

Fastness to Washing:
In the test, change in color of the textile and also staining of color on the adjacent fabric are assessed. A 10 x 4 cm swatch of the coloured fabric is taken and is sandwitched between two adjacent fabric and stitched, The sample and the adjacent fabric are washed together. FIve different types of washing are specified as different washing mthods.

Fastness to Wash
Sr.No	Method	Washing severity	Soap+Soda in grams/liter	Time in minutes	Temperature	Steel balls
1	IS:687:79	Very mild like hand wash	5	30	40+/- 2	Nil
2	IS:3361:79	5 times severe than method 1	5	45	50+/- 2	Nil
3	IS:764:79	Mild washing	5 + 2	30	60+/-2	Nil
4	IS:765:79	Severe washing	5 + 2	30	95+/-2	10
5	IS:3417:79	Severe washing	5 + 2	4 hrs	95+/-2	10

 

The solution for washing should be prepared to the required temperature of washing. The liquor material ratio is 50:1 . After soaping treatment, remove the speciment, rinse twice in cold water and then in running cold water under a tap. Squeeze it and air dry at a temperture not exceeding 60°C. The change in color and staining is evaluated with the help of grey scales.