Why the anti-static wrist strap must touch the human skin?
Cotton and most clothing are insulative, when using an anti-static wrist strap, an insulating layer should not be placed between a person's skin and the conductive part of the wrist strap, this may prevent the anti-static wrist strap from dissipating the electrostatic charge The purpose of eliminating from the person.
The Anti-Static Association standard for wrist straps is ESD S1.1, "Visual inspection of the wrist strap cuff to ensure it fits snugly against the skin".
ESD S1.1 Section 6.1.6, Human skin can have a high electrical resistance. Use of an expandable metal cuff and/or dissipative lotion or gel may reduce a person's resistance to skin contact. "
ANSI/ESD S20.20 Table 1. The recommended specification range for wrist strap systems is less than 35 x 10^6 ohms.
ESD S1.1 Section 3. Definition of terms, Wrist Strap System "An assembled device consisting of a wrist strap and a ground wire that electrically connects a person's skin to ground."