In fact for ESD work, cotton socks should be required. For laboratory testing purposes, only cotton socks are allowed, they are worn for a minimum of 2 hours prior to the beginning of tests and moisturizing lotion is used. These precautions make sure the testing persons are uniform in their contact resistance with the shoe. The dead layer of skin on people is not a fixed thickness or moisture content. This leads to gross differences in the contact resistance of the skin especially on the foot with any electrode system such as an ESD shoe.
Older persons have thicker and drier skin on their feet than young people.
When using ESD shoes people with a high foot resistance should use a moisturizing lotion on their feet before they wear shoes, which require a specified conductance to ground during a test. Once the skin contact resistance is made uniform by moisture content, the body resistance of the person involved in the tests is less important. In fact the body resistances of most people once the dead layer of skin has been moisturized are very close and fairly low compared to the other resistances involved. Just as the skin of the foot plays a very important part in the testing of shoe resistance with a person involved, the hand is just as important. Some people have extremely high skin resistance especially on their hands and fingers.