As part of the GHR 510(k) submission to FDA ( Stephens 1990), the manufacturer paid Edwin LeMaster to perform tests on human hair conductivity. LeMaster compiled an unpublished report that echoes observations made by similar reports:
Hair is a poor conductor of electricity.
Wet hairs conduct better than dry, but they’re still a poor conductor.
The tiny amount of electricity is conducted along the outer hair, not through it.
LeMaster’s study is flawed. Where the Feughelman study he cites measured water content in hair to ensure a controlled experiment, LeMaster does not measure moisture content of hairs. He acknowledges this flaw, stating, "Further studies of these electrical properties will be carried out using samples for which the moisture content can be documented."
Despite some methodological issues, LeMaster concludes that using a conductive solution similar to those sold as part of GHR treatment "only affects the outer surface resistance because when the sample is exposed to the atmosphere the surface dries out and the resistance promptly increases."
For similar conclusions, see:
van Orden, 1998
van Orden states: "Soaking or coating the hair shaft with an electrolyte can, of course, provide a conductive path along the outside surface of the hair, but studies indicate that such applied current would likely dissipate through the skin at the follicle opening and not penetrate fully to the papilla. Any test of hair conductivity must eliminate the effects of possible current flow along the hair surface through a conductive coating."
Commenting on the van Orden study above, Feughelman states, "The only way to obtain any significant current flow would be to apply to the hair fibre some kind of conducting electrolyte in the form of possibly a gel to obtain sufficient conduction on each hair fibre."
Schuster notes that "a very small current can be conducted over the hair surface through the electrolyte coating, not the hair fiber itself. In addition, such current would readily diffuse upon contact with the follicle walls past the infundibulum and little, if any, would reach the papilla."
Schuster also conclusively demonstrated that energy stops traveling down a hair upon contact with a more conductive surface like skin, as hypothesized in Ruggera (1991).