1. Color fastness to washing

Color fastness to washing, also known as color fastness to washing/color fastness to soaping, is to evaluate the color fading of the original fabric and the staining of the lining during the washing process of the fabric.

Test principle: The textile sample is sewn together with one or two specified standard lining fabrics, placed in a soap solution or a mixture of soap and anhydrous sodium carbonate, mechanically agitated under the specified time and temperature conditions, and then washed and dry. Using the original sample as a reference sample, use a gray sample card or an instrument to evaluate the discoloration of the sample and the staining of the lining fabric. (For the specific operation steps, please click: Video│Soaping Color Fastness Test Method)

2. Color fastness to water

The color fastness to water, also known as the color fastness to water stains, is to evaluate the fading of the original fabric and the staining of the lining after the fabric is soaked in water.

Test principle: Combine the textile sample with a multi-fiber lining fabric or two specified single-fiber lining fabrics, immerse in water, squeeze out the water, place it between the two flat plates of the test device, and withstand the specified pressure, After a certain period of time, take out the sample and the lining fabric to dry, take the original sample as the reference sample, and use a gray sample card or instrument to evaluate the discoloration of the sample and the staining of the lining fabric.

The former color fastness to water washing (soaping) requires a soaping process, while the latter water (water stain resistance) color fastness only needs to be soaked in water.

How to test the color fastness to water?

The national mandatory standard GB 18401-2010 "National Basic Safety Technical Specification for Textile Products" has different assessment requirements for product categories of water fastness. as follows:

Class A products (textile products for infants and young children) ≥ grade 3-4

Class B products (products that come into direct contact with the skin) ≥ Class 3

Class C products (products that are not in direct contact with the skin) ≥ Level 3

(The level of color fastness to water is divided into 1 to 5, the larger the value, the better the color fastness).

There are currently three main testing methods for the color fastness of textiles to water: AATCC 107-2003, ISO 105-E01:2003, GB/T 5713-2013

Today, we take the national standard GB/T 5713-2013 "Textiles - Color Fastness Test - Color Fastness to Water" as an example to learn its detection method:

1. Prepare the samples for testing and ensure that the samples are clean and tidy. To avoid defects and stains, take a sample of 40mm×100mm, contact the front side with a piece of 40mm×100mm multi-fiber lining fabric, and sew along the short side to form a combined sample.

Or sandwich the sample between two 40mm × 100mm single-fiber lining fabrics, and sew along the short side to form a combined sample.

2. At room temperature, place the combined sample in a flat-bottomed container, pour tertiary water with a liquor ratio of 50:1, and leave it for 30 minutes at room temperature. Press and move from time to time to ensure the completeness of the combined sample. soaked.

3. Take out the combined sample, scrape off the excess test solution above the sample, then place the sample flat between two glass or acrylic resin plates (no matter how many samples, there must be 11 plates), and place it in the pre- In a hot test device, it is subjected to a pressure of 12.5KPa±0.9KPa.

4. Put the test device into the incubator and keep it at (37±2)℃ for 4h.

5. Take out the test device, unfold the combined sample so that the sample and the backing are connected by only one suture (all sutures can be disconnected if necessary), and hang it to dry in air at a temperature not exceeding 60°C. (Note: If the sample is found to be dry, it must be discarded and re-tested.)

6. Use a gray sample card or instrument to evaluate the discoloration of the sample and the staining of the lining fabric.

What are the influencing factors of color fastness to water? What are the ways to improve it?

Influencing factors of fabric color fastness to water

1. Water has a plasticizing effect on the hydrogen fiber. Under wet conditions, the dyes entering the amorphous area of the hydrogen fiber tend to migrate to the surface of the fiber. Staining.

2. When there is too much dye floating on the surface of the fabric that is not stably combined with the fiber, it will affect the water fastness of the textile.

3. The dye retarder added in the dyeing process will not only play a leveling role, but also weaken the bonding force between the dye and the fiber, making the test result of water fastness unsatisfactory.

4. If some auxiliaries added during dyeing and post-treatment are not removed after dyeing, the residual auxiliaries will have a profound impact on the color fastness to water.

Method for improving the color fastness of textiles to water

1. When selecting dyes, dyes with high fixation rate and good stability should be selected for dyeing.

2. Reasonably formulate and control the dyeing process, strengthen the fixing conditions, and form a covalent bond with high stability, so that the dye can be fully fixed.

3. Textiles with dark colors should be dyed with dyes with high dyeing rate, and the dyeing saturation should be able to reach the required color depth.

4. Choose appropriate dyes according to the composition of the textile, choose appropriate auxiliaries according to the variety of dyes, and remove the residual dyes and auxiliaries after dyeing.

5. When soaping and washing, it should be fully washed to remove the floating color on the surface of the fabric.

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