When should a client have a patch test before a chemical treatment?

A client should have a patch test 48 hours prior to a chemical treatment to ensure they do not have an adverse reaction to the product being used. This time frame allows enough time to observe any potential allergies or sensitivities that may arise from the chemical formulation. By performing the test 48 hours in advance, the stylist or barber can monitor for any signs of irritation, redness, or other allergic responses.

If a patch test is conducted too soon before the service, the results may not accurately reflect the client's reaction, especially if there are delayed responses to a product. Performing the test after the service would be ineffective, as any adverse reactions would not be preventable at that point. Thus, the 48-hour window strikes the right balance of safety and effectiveness for assessing client tolerance to chemicals.