The leather rubbing color fastness tester is used to evaluate the color fastness of leather materials. The working principle of this tester involves rubbing a specified dry or wet cloth against the leather surface and assessing the color transfer or changes.

Here is a breakdown of the working principle:

1. Specimen Preparation: A leather sample is fixed onto a holder or mounted onto a rotating drum, depending on the design of the tester.

2. Friction Mechanism: The tester applies a rubbing motion to the leather surface using a controlled force and a specified rubbing medium. The rubbing medium can be a dry or wet cloth made of a specific material, such as cotton or wool.

3. Rubbing Process: The rubbing medium is placed in contact with the leather surface, and the holder or rotating drum moves back and forth or rotates in a controlled manner. The rubbing motion causes the rubbing medium to exert pressure and friction on the leather surface.

4. Assessment of Color Transfer: During the rubbing process, the rubbing medium may induce color transfer from the leather to the cloth due to the frictional force. After a certain number of rubs, the cloth and leather specimen are evaluated visually or using a spectrophotometer to determine any color changes or transfer.

5. Test Evaluation: The color fastness of the leather material is assessed based on the extent of color transfer or changes observed on the cloth and the leather specimen. The rating is typically performed according to standard color fastness grading systems.

By subjecting the leather material to controlled rubbing conditions, the tester simulates the friction experienced in real-life scenarios, such as during wear or use of leather products. This helps to evaluate the durability and colorfastness properties of the leather and aids in product quality control and improvement.