Patch Test

Q: What is a patch test and how do you do this test?

A: A patch test is a safety procedure that determines whether a hair salon client has an allergic sensitivity or adverse reaction to the chemicals used in hair services. This simple yet important test involves applying small amounts of the intended chemical products to a discrete area of skin and monitoring for any negative reactions over a 24 to 48-hour period.

The importance of patch testing cannot be overstated in hair care. Chemical services such as hair coloring, perming, and straightening all involve potent formulations that can cause severe allergic reactions. What might seem like a minor skin sensitivity can escalate dramatically when chemicals are applied to the entire scalp and hair, where exposure time is longer and the surface area much greater.

Hair stylists should make patch testing a standard practice before any chemical service, regardless of whether the client has previously used similar products or claims to have no known allergies. Skin sensitivity can develop at any time, and different product formulations may contain varying ingredients that could trigger unexpected reactions.

The Patch Testing Procedure

To perform an effective patch test, begin by gathering all the chemical components you plan to use. Select an appropriate testing location on the client's skin. The most common and effective spots are behind the ear near the hairline at the nape of the neck, or on the inner forearm about two inches or 5 cm below the elbow crease. These areas are relatively hidden from view while remaining easily accessible for monitoring. Clean the chosen area gently with a mild soap and water, then dry thoroughly to ensure accurate test results.

Using clean cotton swabs or small disposable applicators, apply a small dab of each chemical component to the prepared skin area. Each application should be spaced at least an inch or 2.5 cm apart from other test spots. Make a simple sketch or take a photo to document which product was applied where, as this information becomes crucial if a reaction develops. Allow each application to air dry completely without rubbing or wiping the area.

Instruct your client on proper aftercare during the waiting period. The client should avoid washing or scrubbing the test area, refrain from applying lotions or other skincare products to the region, and resist any urge to scratch or touch the spots even if mild itching occurs. The test area should remain undisturbed for the full monitoring period to ensure accurate results.

The critical observation period spans 24 to 48 hours after application, though reactions can sometimes appear within just a few hours for highly sensitive people. Schedule a follow-up appointment or a phone call to evaluate the results before proceeding with the intended service. Some hair salons prefer to conduct patch tests 48 hours before a scheduled appointment to allow maximum reaction time.

During the monitoring period, both the stylist and client should watch for several types of reactions. Reactions indicating sensitivity include redness or inflammation around the test site, raised bumps or welts, excessive itching or burning sensations, blistering or open sores, and any swelling extending beyond the immediate application area. Even seemingly minor reactions like slight pinkness or mild itching should be taken seriously, as these symptoms often intensify significantly when exposure increases during the full chemical service.

If any signs of reaction appear, the planned chemical service must be cancelled. When patch test results show no adverse reactions after the full 48-hour period, it's generally safe to proceed with the chemical service. However, stylists should still monitor the client closely during the actual service and be prepared to stop immediately if any unexpected reactions develop.

Patch testing provides strong indication of safety but doesn't guarantee that reactions won't occur, particularly if application techniques or timing differ significantly from the test conditions.

©Hairfinder.com

See also:

How to perform a strand test

Hair porosity test