What is colour fastness

Colour Fastness

The term colour fastness can be described as the ability of colouring matters on the fibre to withstand the physical and chemical actions during the processes of manufacture and in daily use of the dyed material.Most important part for every garments. Color fastness of a textile material mainly depends upon four factors:

The nature of the fibre;
The nature of the dyestuff;
The depth of shade;
The method of dyeing or printing employed.

Grey Scale

The visual assessment of color change caused by a particular agency (apart from light fading) is assessed as the colour contrast between the original and tested sample using a grey scale. Grey scale is a 5 pairs of grey color chips showing visual differences in colour. The grades are coded from 1 to 5,  poor, moderate, good, very good, and excellent respectively. They are two types:
Grey scale for assessing colour change (One sample of each pair is always the same medium grey, the other halves vary from a pale grey to the standard grey)
Grey scale for assessing stain (One sample of each pair is always white, the other halves a grey of increasing depth from white to medium grey)

Assessment of color fastness:

This involves a visual determination of either change in shade or staining of an adjacent material. Color fastness of a dyed textile is mainly considered against the actions made by light, wash, rubbing and perspiration. After a fastness test, the original and tested samples are placed side by side along with the grey scale and the extent of colour loss evaluated.

For example, if a dyed sample during wash fastness test shows no change in colour, there will be no staining of white sample too. The wash fastness will be expressed as ‘change in colour-5 and degree of staining-5, excellent wash fastness.