7. Common Q&A for Color Fastness testing
Q1. When the knitting product standard does not specify the friction sampling requirements, is the horizontal assessment evaluated?
(1). If the product standard stipulates that it is only straight, it should be implemented according to the standard;
⑵. Sampling requirements are not specified in the product standard, and both vertical and horizontal measurements are taken
Try to test every color as much as possible, and remark those that cannot be tested horizontally.
Q2. How is the Color Fastness to rubbing of woven fabrics evaluated when it is stated in the standard for knitted products that only the vertical direction is evaluated?
The woven fabrics are assessed in the warp and weft directions.
Q3. In GB/T 14576-1993 “Textile Color Fastness Test, Lightfastness and Perspiration Composite Color Fastness,” how should the rating be determined when the sample is unevenly discolored after the test?
According to the most severe discoloration rating.
Q4. SN/T 0309-1994 “Methods for the Inspection of Fluorescent Substances in Imported and Exported Textile Materials,” under ultraviolet light, the fabric has a bit-like, strong fluorescent luster (non-removable impurities). Can this situation be defined? Does it contain fluorescent substances?
It is defined as containing fluorescent substances.
Q5. For multi-component fiber textiles, choose lining fabrics. Can fibers of the same category fall into one category? For example, Fabric fiber content: 45% cotton, 25% polyester, 15% wool, 15% rabbit hair. Can wool and rabbit hair be classified as wool, and cotton and wool should be used for single fiber lining?
When choosing lining fabrics, fibers of the same category can be classified into one category, and lining fabrics can be selected according to corresponding standards.
Hemp: ramie, flax, jute, kenaf, etc. viscose, modal, lyocell, Cupra, etc.; wool: wool, rabbit hair, mohair, etc.; silk: mulberry silk, tussah silk Wait.
Q6. Since the test temperature of Color Fastness to washing is selected according to the composition, can the surface and lining be tested only according to the fabric’s composition when testing the garment?
According to the standard requirements, the washable temperature of the fabric and lining is selected according to their respective components.
Q7. After narrow-striped fabrics, printed fabrics, and yarn-dyed fabrics undergo Color Fastness tests (water resistance, perspiration resistance, soaping resistance), the samples’ degree of discoloration after the test is different. How to grade and judge?
When preparing samples, take the darker color as much as possible on the dark and light parts. Multiple combined samples can be cut and graded and judged according to the most severe discoloration for multi-color fabrics, wide and narrow striped fabrics.
Q8. GB 12982-2004 “National Flag” If the customer cannot provide radiant energy, how to determine the end of exposure?
Refer to 7.2.3 (Method 3) of GB/T 8427-1998 “Textile Color Fastness Test Color Fastness to Artificial Light: Xenon-Arc.”
Q9. There is no clause 6.2.3 in GB/T 8427-1998 “Textile Color Fastness Test Color Fastness to Artificial Light: Xenon-Arc” standard. Does the GB 12982-2004 lightfastness test method correspond to 7.2.3?
The lightfastness test in GB 12982-2004 shall be implemented in accordance with 7.2.3 in GB/T 8427-1998.
Q10. During the Color Fastness test of woolen fabrics, there are spots and stains. How to rate it?
According to the deepest spots.
Q11. During the test of Color Fastness to perspiration and water fastness, water stain marks appear on the samples after the test, and the water stain marks disappear after rubbing by hand. How to rank?
After removing the watermark, grade it.
Q12. How to choose a lining for the Color Fastness test of silk and acetate fiber blended fabrics?
Single fiber lining is used according to the following standards: GB/T 7568.8-2014 “Textile Color Fastness test standard for lining fabrics Part 8: Diacetate fiber” and GB/T 7568.6-2002 “Textile Color Fastness test wire standard sticker Lining fabric specifications.
8. Reasons for poor Color Fastness of silk fabrics and their care
The major component of silk fabrics is natural protein fibers. This feature makes it more breathable and softer than other fabrics. But also because of this characteristic, the mulberry silk fabric has an insurmountable shortcoming. That is, the Color Fastness is not high.
Proteins don’t do well at high temperatures, so mulberry silk fabrics cannot accept high-temperature processing. In the dyeing process, high-temperature dyeing and high-temperature fixing cannot be carried out. This is a major reason why its Color Fastness is not high.
Furthermore, protein is easily damaged in an alkaline environment, so acid dyes are generally used for dyeing. The fabric dyed with acid dyes is bright and full, but the Color Fastness is not high.
A large part of silk fabric colors is bound to fade. This includes lighter shades of light yellow, silver-gray, pink, light green, light blue, etc., and silk clothes of these colors are not resistant to sunlight. Among the silk fabrics of medium shades, most brighter colors are easy to fade, such as gold, orange, light green, brilliant blue, brilliant pink, ground red and the likes. The worst colors are gray and certain dark colors, such as grass green, various types of gray, brownish yellow, camel and the likes. Most dark silk clothes are easier to fade, especially red, purple, brilliant blue, plum green, etc. They are almost bound to fade.
Detergent selection: Chemical detergents are generally not suitable for silk fabrics. If it is underwear or contains dirty stains, it is recommended to use a neutral bath liquid for washing.
Water temperature control: high water temperature is the second killer of silk fabrics. When washing, do not use hot water soaking, be sure to use cold water at room temperature, and avoid soaking for a long time. Otherwise, it will cause the silk to turn yellow or fade. If you use hot water and soak for a long time, it would even stain the whole pot of water!
Method of scrubbing: Silk fabrics are different from pure cotton and chemical fiber fabrics. No silk fabrics can be machine washed. When washing at home, you must use hand wash and do not rub vigorously. It is advisable to use “washing” or “rinsing.” Wherever you can, use a soft towel dipped in the detergent to wipe gently, preferably not scrubbing.
Final drying: Silk has poor light resistance, and long-term absorption of ultraviolet rays will cause yellowing and hardening. Therefore, when drying, you must avoid direct sunlight and place the reverse side of the clothes in a cool place. When they are 80 to 90% dry, take them off and iron them with a medium-low temperature iron to keep the clothes shiny and durable. Also, avoid spraying water when ironing, and ensure to not iron it from the front to avoid water stains.