Patch testing is primarily used to identify potential irritants before applying to the face.

• A. To identify potential irritants before full application.
• B. To determine the client's blood type.
• C. To assess fragrance preference.
• D. To measure skin elasticity.

Answer: (A)

Patch testing focuses on spotting substances that may irritate or trigger an allergic reaction on the skin before a full facial application. By placing tiny amounts of suspected irritants on a small skin area and watching for redness, swelling, or itching for about 24 to 48 hours, you can tell which ingredients to avoid and select products that are safe for the client. It’s not used to determine blood type, assess fragrance preference, or measure skin elasticity, so those goals aren’t what patch testing aims to achieve.