Colour fastness of textiles (hereinafter abbreviated as colour fastness) refers to the degree of fading for dyed or printed fabrics under the influence of external factors (extrusion, friction, washing, rain, sun exposure, light, seawater impregnation, saliva impregnation, water impregnation, sweat impregnation, etc.) in the process of use or processing. It is an important index of fabrics. If colour fastness is good, textiles are easy to fade in the process of post-processing or use; Poor colour fastness will lead to the fading or staining of textiles, which will spoil the beauty of wear, and harm health.
The quality of colour fastness of textiles is not unfamiliar to most consumers, for example, black jeans turn grey after being washed twice, new socks dye your soles, white bottom shirts are “polluted” by dark sweaters, and silk dresses become colourless after being washed only once. These quality problems related to colour fastness have been bothering us, and are also major issue of consumer complaints. From this year’s spot checks of textiles and clothing by various national quality supervision departments, the unqualified colour fastness occurs frequently.
Then, in the terms of textile testing, you’d better had a general understanding of the following issues:
What are the bases for testing colour fastness of textiles?
What are the common items of colour fastness test items?
What are the difficulties in the testing process?
How to judge colour fastness of some special clothes?
What items are included in colour fastness test of textiles? What are the test criteria? Which colour fastness items must be tested for all textiles? Which items are textiles designed for special people or special functions?
There are many testing items for colour fastness, and the main items frequently checked in technical specifications or product standards are as follows:
AATCC 61, ISO105-C01, GB/T 5713 colour fastness to water
AATCC 15, ISO 105-E04, GB/T 3922 colour fastness to perspiration
AATCC 8, ISO 105X12, GB/T 3920 colour fastness to rubbing
DIN 53160, GB/T 18886 colour fastness saliva
ISO 105-D01, GB/T 5711 colour fastness to dry cleaning
AATCC 16, ISO 105-B02, GB/T 8427 colour fastness to light
AATCC 23, ISO 105-G02 colour fastness burnt-gas fumes
AATCC 106, ISO 105 E02, GB/T 5714 colour fastness to sea water
AATCC 92, ISO 105, GB/T 5718 colour fastness to ironing and sublimation
The main colour fastness items that textiles must be tested are colour fastness to water, to perspiration and to rubbing. In addition:
Colour fastness to saliva is generally checked only for infant textile products.
Colour fastness to dry cleaning is generally checked only for the products labeled in the instructions for the use of garments that can be dry cleaned.
Colour fastness to light is generally assessed only on the textiles exposed in the use process, such as jackets, hats, bedding, etc. Underwear products are not assessed.
colour fastness to sea water is generally assessed only on swimsuit fabrics.
Colour fastness to burnt-gas fumes and to ironing and sublimation only consider textile products in special working occasions.
What are the common unqualified items of colour fastness of textiles? What are the reasons for disqualification?
According to laboratory testing experience, among the all kinds of supervision inspection and consumer complaints, the common unqualified items of colour fastness to rubbing, saliva, light fastness and to perspiration. Factors that affect colour fastness of textiles are many, such as unqualified selection of dyes and auxiliaries, inappropriate fabric, dyeing and finishing process, etc.
For clothing with complex structure, how to test colour fastness and evaluate whether it is qualified?
In colour fastness test, sample printed and yarn-dyed products with large pattern cycle or irregular pattern for separative test, and then take the lowest grade as the test result.
Colour fastness of small components with a weight not exceeding 1% of the whole product is not assessed for products directly or indirectly exposed to skin.
The popular winter stormwear on the current market, composed of inner grab sweater plus outer stormwear, can be worn as a whole or can be split into two pieces to wear separately. When testing colour fastness of this kind of clothing, it should be used as two pieces of clothing to test and evaluate separately.
What are the difficulties or points needing attention in testing and judging colour fastness of textiles? For inspectors, how to improve the accuracy of judgment?
The testing principle and process of colour fastness testing are generally simple, but sometimes the results of laboratory testing are inconsistent for the same fabric. An important reason for this phenomenon is the difference of people’s eyes. Rating, the key step of colour fastness testing, is for inspectors to observe the colour changes of samples and lining fabrics with the naked eye. This subjective evaluation method is susceptible to the influence of external conditions and the psychological activities of the experimenters themselves, resulting in inconsistent rating results.
It is suggested that each laboratory should regularly carry out internal and external eye comparisons to ensure the stability and consistency.
For consumers and distributors, is there a simple and fast way to distinguish whether colour fastness is qualified?
For consumers and distributors, if they want to distinguish colour fastness in a simple and fast way, they can use a cotton white cloth to rub the surface of the fabric. If the white cloth is heavily stained, it means that the fabric is heavily floated and colour fastness is likely to be unqualified, so they should choose carefully.
Colour fastness of textiles is an important index for evaluating the quality of dyed and printed textiles, and it is also one of the quality problems that consumers care about and complain about. As a key step in evaluating colour fastness of textiles, the test must be carried out in strict accordance with standards. Therefore, in the test process, a tester must have rich experience to ensure the accuracy of the test results, and the color fastness test instrument must have sufficient stability to ensure the repeatability of the test results. For example, Electronic Crockmeter, Perspiration Tester, Light Fastness Tester and so on, which are good helpers for testing colour fastness of textiles.