Foaming when Layering?

Have you ever experienced this?

After cleansing, you apply toner, essence, or serum... and they get slimy to the touch. There's foam.

So you wait for the product to dry, rinse again, or scrub harder. But even without any cleanser left on the skin, some products are just notorious for foaming when layered with others. Here's how to prevent it.

Why does foaming happen?

When the right ingredients mix to create the wrong properties, air can get trapped in the formulation.[1] Like shaking a bottle of soda, the act of massaging the skin introduces air into the product, resulting in a foamy texture.

The reaction doesn't mean that something harmful is taking place.

How do I find the culprit?

1Review the ingredient list for surfactants

Take a look online. For example, products with niacinamide often foam easily, because many are formulated with mild surfactants to help emulsify the formula.[2]

2Test and eliminate

Use each product individually, then in small combinations, to see which mix is creating the foam. Often a product is fine on its own (brands and manufacturers work hard to get the texture right), so it's the pairing of two items that creates foam.

For foam to form, you need a molecule with two personalities: one part that grabs onto water so it stays soluble, and another part that repels it. Molecules like that gather along the boundary between air and liquid, which is what lets a bubble hold its shape instead of popping.[3]

3Minimize rubbing

Massaging a product into the skin traps air bubbles in the formulation, and surfactants then stabilize those bubbles so they don't collapse on their own.