The rubbing fastness test is the fastness test performed to check the durability of the color when dyed and/or printed textile products are rubbed dry or wet.
The rubbing fastness test is performed by rubbing the test sample placed in the crockmeter and the accompanying cloth against each other. At the end of the test, staining of the accompanying cloth is evaluated with a gray scale.
The rubbing cloth is a 5x5 cm, undyed, bleached cotton fabric that does not contain starch or finishing substances, which helps to carry out the test.
By attaching the rubbing tip on the upper part of the rubbing fastness tester, it is observed that the sample stains the rubbing cloth by rubbing.
For the rubbing fastness test, the appropriate size test sample is cut and prepared. The process of preparing the test sample varies according to the form of the sample:
If the sample to be tested is yarn, the yarns are knitted and turned into fabric. It is cut in 14x5 cm size or tightly wrapped on a cardboard of suitable size, parallel to the rubbing direction. The wrapping frequency should be adjusted so that the cardboard is not visible.
The sample fabric to be tested is cut into 14 pieces of 5x4 cm size (two for wet rubbing fastness and two for dry rubbing fastness.). While cutting the samples, care should be taken to cut the long side of two of them in the weft direction of the fabric and the other two in the warp direction of the fabric.
Rubbing Fastness Tester (Crockmeter)
The rubbing fastness tester (crockmeter) is used to determine the color fastness of textile products to dry or wet rubbing. The rubbing tip, on which the rubbing cloth is attached, has a diameter of 16 mm. The friction tip helps to perform the test by applying a force of 9 N to the test specimen.
The sample holder is usually with needles. These pins ensure that the test specimen placed in the specimen holder remains smooth and stable. There are hand-operated rubbing fastness testers as well as digital electronic ones. Up to 1000 rubbing can be done by entering the value to the digital electronic rubbing fastness devices beforehand.
The rubbing fastness test should be done in rooms with a temperature of 21 °C and a humidity of 65±3%. In order to prevent the room from being affected by external factors, care should be taken to have a double door and to open the 1nd door after the 2st door is closed at the entrances and exits.
The sample to be tested is properly placed in the sample holder located at the bottom of the rubbing fastness tester. A rubbing cloth is attached to the rubbing tip on the top of the device. The rubbing cloth attached to the rubbing tip is rubbing against the test sample by manually or automatically coming and going 10 times in 10 seconds. After the procedure is completed, the rubbing cloth is removed. If there is colored feather, pile, fiber etc. on it. If there is, it is cleaned and the color of the cloth staining is evaluated with the gray scale.
After the test samples cut in the warp and weft direction of the fabric are tested separately in the device, the value in whichever staining is more is accepted as the result.
Types of Rubbing Fastness
The rubbing fastness test takes place in two ways:
>>>>> Dry rubbing fastness
>>>>> wet rubbing fastness
Dry Rubbing Fastness
In the dry rubbing fastness test, the sample and rubbing cloth are dry.
Wet Rubbing Fastness
The wet rubbing fastness test is done with the test sample dry and the rubbing cloth moistened with water. While the rubbing cloth is wetted, it should be ensured that it absorbs 100% of its weight. At the end of the test
The rubbing cloth should be evaluated after drying at room temperature.
Evaluation of Rubbing Fastness Test
Rubbing staining of the tested sample is checked and evaluated using the gray scale.
Two types of gray scales are used for the rubbing fastness test. One of them is 2 scale. The lowest fastness value is “5” and the highest fastness value is “1”. The other gray scale is 5 scale. In this scale, the lowest and highest fastness values are the same as in the 9-scale scale. However, there are intermediate values between each value. Therefore, more precise measurements can be made. Fastness values in 5 scale gray scale are as follows.
1-------------------------------- Lowest fastness value
5-------------------------------- Highest fastness value
Evaluation is done in a dark room under D65 daylight in a light booth. The light should come at a 45° angle to the sample, but the view should be perpendicular to the sample. Evaluation is made by placing the sample on the 45° angled stands in the light cabinet.
In order to evaluate the rubbing fastness test, the rubbing cloth stained as a result of the test and the clean rubbing cloth are placed side by side on the open stand in the light cabinet. In order to prevent the appearance of the samples from being affected, the untested sample is laid on the floor and examined on it. The difference between the stained rubbing cloth and the clean rubbing cloth placed side by side is evaluated by the corresponding number on the gray scale. The number obtained is the degree of rubbing fastness of the color.