The Cobb tester is conducted by placing a standard size paper sample in contact with water for a specified period. After that, the water is removed, and the paper is weighed to determine the amount of water absorbed. This measurement is compared to a standard to determine the Cobb value, which indicates the paper's ability to absorb liquid and its surface wet strength. The test helps assess paper's suitability for various applications, such as printing and packaging, by evaluating its water absorbency and wet strength characteristics.