Measurement Of Rubbing Fastness

Principle

Specimens of textiles are rubbed with dry rubbing cloth and with wet rubbing cloth by means of rubbing finger of specified dimensions. The staining of rubbing cloth is assessed with the grey scale for staining. The ratings are assessed for dry rubbing and wet rubbing fastness of the specimen. The procedure followed by ISO method.[ISO-105-X12].

Sampling

The sample shall be selected so as to be the representative of a sample of the lot or as agreed to between the buyer and seller.

Apparatus

A crock meter is used which consists of a flat surface to hold the specimen and a rubbing finger of 1.6mm diameter to have a to and fro motion in a straight line along a 10cm track on the specimen with a downward force of 9 Newton’s.

Rubbing Cotton Cloth

This should be bleached without any finish and cut it into a size of 5 x 5 cm.

Test Specimen

It should not be less than 14 cm x 5 cm. Two pieces are to be used one in warp way and one in weft way for dry rubbing test. Similarly, for wet rubbing test, two pieces are to be used.

Procedure

• Fix the test specimen to the rubbing device by means of clamps such that the long direction of the specimen follows the track of the device.
• Dry Rubbing

1. Dry rubbing cloth is fixed flat in place of over the end of the finger of the device.
2. Fix the test specimen to the rubbing device by means of clamps such that the long direction of the specimen follows the track of the device.
3. Operate the apparatus and rub the test specimen to and fro in a straight line along the track to 10 times with the downward force of 9 Newton’s.
4. Remove the test specimen out and compare it with the standard fabric for staining test. Assign the rating by using the grey scale for staining.
5. Each test is conducted for warp and weft way directions of the fabric.

• Wet Rubbing

1. Fix the test specimen to the rubbing device by means of clamps such that the long direction of the specimen follows the track of the device.
2. A standard cloth is wetted for 10 min. in a disc containing distilled water to take-up about 100%.
3. Then it is fixed flat over the end of the finger of the testing device.
4. Operate the apparatus and rub the test specimen to and fro in a straight line along the track to 10 times with the downward force of 9 Newton’s.
5. Remove the test specimen out and compare it with the standard fabric for staining test.Assign the rating by using the grey scale for staining.
6. Each test is conducted for warp and weft way directions of the fabric.

Evaluation Of Colour Fastness To Rubbing

The composite specimens containing the specimen is evaluated with the grey scale for.

1. Change in color
2. Staining

The grey scale consists of 9 pairs of standard grey chips, each pair representing the difference in colors (shade and strength) corresponding to the numerical fastness rating. This rating may be described in qualitative terms as follows.

Grey Scale Rating For Rubbing Fastness Testing