Color Fastness to Rubbing/Crocking Measuring Procedure

color fastness to rubbing

Color fastness to rubbing refers to the degree of color fading of dyed fabrics after rubbing, which is divided into color fastness to dry rubbing and color fastness to wet rubbing. It’s also known as color fastnesss to crocking. The test method for the color fastness to rubbing of textiles is one of the methods for measuring the color fastness of textiles, and it is an important assessment index for the color fastness of textiles.
The color fastness to rubbing is to assess the resistance of dyes to mechanical friction. The principle is to rub the textile sample with a dry rubbing cloth and a wet rubbing cloth to evaluate the staining degree of the rubbing cloth.

How to test rubbing fastness(depend on iso 105 x12)

Purpose

To measure the resistance of the color of textiles to rubbing and staining to other materials, and to reflect the quality of the color fastness to rubbing of textiles through the color difference rating of staining.

Preparation

  1. Rubbing fastness tester: it can rotate. Contains a friction finger with a diameter of 25±0.1mm, which can rotate 405±3 degrees, and the vertical pressure is 11.1±0.5N. The diameter of the other friction finger is 16 ± 0.1mm, and the vertical pressure is the same.
  2. Cotton cloth for friction: After desizing and bleaching, the cotton fabric does not contain any finishing agent. Cut it into a square of 50mmX50mm±2mm.
  3. Waterproof sandpaper, or a drip net with a stainless steel wire diameter of 1mm and a mesh width of about 20mm.
NOTE: When using stainless steel wire or sandpaper, be aware that it may leave marks on the fabric that will affect the final grading. Sandpaper is best used when testing textiles.
  • Gray scale: used for assessing staining, and should comply with ISO 105-A03.

Sampling

  • If the tested textile is fabric, the sample size should not be smaller than 25mmX25mm. If the accuracy of the test is required to be high, another sample can be taken for testing.
  • If the textile to be tested is yarn, weave it into a fabric, and ensure that the size of the sample is not less than 25mmX25mm. Or wind the yarn in parallel on a cardboard with the same size as the sample to form a layer.
  • Before the test, place the sample and friction cloth in an atmosphere with a temperature of 20±2°C and a relative humidity of 65±2% for at least 4 hours. When conditioning, put the sample and rubbing cloth on a flat net or a perforated shelf respectively. Certain fabrics, such as cotton or wool, take longer to condition.
  • Preferably also the test is carried out under standard atmospheric conditions for textile testing (see ISO 139).

Operation steps

General
Tilt the upper half of the crock tester open to expose the rotating rubbing fingers. Fix the specimen on the base plate of the tester next to the vertical rod, placing the rubbing area on the rubbing finger. Return the upper part of the instrument to the operating start position with the rubbing cloth in contact with the specimen at the end of the shaft. The downward pressure of the vertical axis is 11.1±0.5N. Make the length direction of the sample coincide with the stroke direction of the instrument. Place a net or waterproof sandpaper between the base plate of the tester and the specimen to reduce movement of the specimen. The prepared samples were tested according to both wet and dry procedures.
When testing textiles in multiple colors, the sampling location should be chosen carefully so that all colors are rubbed during the test. If the size of each color is large enough, it is necessary to take multiple samples to evaluate the color change independently. If small areas of color are tested together, the equipment described in ISO 105-X16 may be used as an option.
Dry rubbing
Install the conditioned friction cloth on the friction head of the tester, turn the handle for 20 turns, and the vertical axis for 40 turns. Rotate the handle at 1 revolution/second. Remove the test section and conditioned.
Wet rubbing
Weigh the conditioned rubbing cloth, soak it thoroughly in distilled water, and weigh again. The water content is guaranteed to be 95%~100%. Follow the procedure in dry rubbing for rubbing.
Note: The moisture content of the rubbing cloth has a great influence on the result, other moisture content can be used. For example, a commonly used moisture content is 65 ± 5%.
Drying
Air dry the test cloth.
Rating
  1. Remove excess loose fibers on the sample so as not to affect the rating.
  2. When rating, put three layers of unrubbed white cotton cloth behind the tested rubbing cloth.
  3. Under the standard light source, use the staining gray scale (4.4) to evaluate the staining of the cotton rubbing cloth.

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