I was just reading scientific and forensic journals regarding test method and procedure.

Before testing hair, it is cleaned with methylene chloride (paint stripper, more or less) or better yet, petroleum ether (distilled gasoline from what I can understand).

(Petroleum ether is only available to accredited labs, classrooms, ext. It's extremely flammable. It is required storage in ventilated cabinets.)

The hairs, I learned are washed with these substances to remove thc from the outside of the hair follicle. This is to disprove the possibility of the second hand smoke excuse.

Sounds like paint stripper is the best readily available substance to remove thc, unless you work at a lab. (definitely something to avoid getting in eyes or inhalation)
walnut Reviewed by walnut on . Hair Testing info ideas Hello people. Recently I've taken on a part time work that has been dangling the idea of hair testing over my head. If the time comes, I don't wish to fail. During the last week or so I've been doing a lot doing home work regarding this testing process. Things you all should know. Marijuana is the most difficult drug to detect (so far) with this type of test. I recommend reading the information given strait from the companies you can personally order the tests from. Google it. Rating: 5