How to Do a Lash Patch Test the Right Way

An allergic reaction to the adhesive is one of the most important topics for a lash artist. All lash adhesives contain cyanoacrylate, a chemical compound that can cause allergic reactions in some people. But even the pigment in the adhesive can trigger an allergy, since everybody is different and there’s no way to predict a reaction to any given chemical. So it’s important to know how to do a patch test correctly and what to do if a client shows an allergy.

An allergy can develop right after the service, or hours or days later. It depends on the client’s individual sensitivity. To avoid unpleasant consequences, a patch test is a good step before working with a new client, especially if she’s getting ready for a big event like a wedding and has never had extensions before, or hasn’t had them in a very long time.

Why can’t you do a patch test on the client’s skin?

It’s all because of that same cyanoacrylate, a very strong chemical that starts releasing a lot of heat on contact with natural fibers like cellulose (paper), cotton, wool, and skin, including human skin. It’s called an exothermic reaction, burning without fire.

Yes, every artist has gotten adhesive on themselves plenty of times without any burns. It’s true that most of the time there’s no burn on skin contact, thanks to the moisture on the skin’s surface: the adhesive meets that moisture first and instantly polymerizes before reaching the skin. But if the skin is dry, a burn is very likely, so there’s no reason to risk it.

Besides, the skin’s reaction to the adhesive isn’t really telling, because during an application we don’t touch the skin, so cyanoacrylate exposure is minimal. The reaction mostly comes from the adhesive fumes during the service and for a few hours after, until the adhesive fully polymerizes (hardens).

By the way, if the maker of the adhesive you use claims it’s hypoallergenic, that’s a reason to be skeptical. There’s no such thing as a hypoallergenic adhesive, and claims like that are nothing more than another marketing move. Every lash adhesive contains some form of cyanoacrylate, it’s currently the only component that hardens instantly, letting the extensions hold their position on the natural lashes.

So how do you do a patch test, and should you?

If a client has an important event coming up where she needs to look 100%, but she hasn’t had extensions in a while or ever, then a patch test is worth doing.

Manufacturers usually recommend this 48 hours before the application: attach a couple of lashes on the outer corners of the eyes using the same materials and products you plan to use in the full set.

That said, with such a small amount of product on first contact, dangerous consequences are minimal, it’s more likely to reveal a very strong reaction. A weaker, slow-building reaction can show up over time, so a patch test isn’t 100% telling, and you should always warn the client about possible consequences.

You can also offer the client a trial full set a few weeks before the event, to fully test her body’s reaction, and to pick, try, and agree on the look she wants, so there are no unpleasant surprises right before the big day.

Happy lashing!