Okla. Admin. Code § 310:210-7-16
All licensed barbers, barber instructors, and barber apprentices shall be individually responsible for product knowledge. Maximum precautionary, safe, sanitary and appropriate preparation prior to service and application, as required by product label, shall be practiced at all times upon the public. Licensees who use a product (s) that requires a patch test before the use or application of the product are required to post an advisory, clearly visible to the client in the area where the product requiring the patch test is used or applied, that advises the client of the manufacturer's requirement to conduct a patch test before the produce may be used or applied. The posting of an advisory shall not be required if the licensee provides the individual with a printed, legible fact sheet containing the manufacturer's requirement to conduct a patch test before the product is used or applied, or secures an informed written release of liability from the client receiving the application of the product requiring the patch test.
Okla. Admin. Code § 310:210-7-16