What Does Breathable Nail Polish Mean?

This story originally appeared on Allure. 

Yes, breathable nail polish is a thing, and no, it's not really that new. The concept first came to be in 2013 when Inglot came out with its O2M Breathable Nail Enamel (in glossy and, later, matte finishes). But the Polish-based company was alone in its offerings until last week, when Orly debuted its new Breathable Treatment + Color line. Now you know the backstory, but the real question is: What the heck is breathable nail polish anyway?

At some point in our lives we've all been told by a manicurist, coworker, or our mom that wearing polish all the time will make your nails brittle and prone to breakage. The idea is that polish creates an impermeable layer that keeps nails from getting the water and oxygen they need to stay healthy (more on all that in a minute). Breathable polish, on the other hand, is designed to allow molecules of water—and their good buddy oxygen—to slip through the polish and down to the nail, thereby supposedlyimproving the health of your nail and nail bed.

The way it works is basic chemistry. See, traditional nail polish is made up of very neat, tight molecular bonds, like straight lines stacked directly on top of each other. But the molecules that make up water- and air-permeable formulas feature a more staggered structure—like a bricklaying pattern—that allows teeny water and air molecules to slip through the spaces. "Traditional polish has fewer interstitial spaces for water to pass through," explains cosmetic chemist Randy Schueller. So how do these breathable polishes pull off a trick like that? "The breathability is not a function of a single ingredient; rather, it depends on how the entire formula is put together," Schueller says, though he notes that ingredients like bis (glycidoxyphenyl) propane/bisaminomethylnorbornane, which appear in some breathable formulas, are not typically used in nail polish and may play a role in this unique molecular structure.

But does regular polish really put your nail health on the line? The idea of giving your nails time to breathe between polish sessions is something you hear on occasion (you've probably received a lecture on it from your manicurist), but there might not be much science to support it. Dermatologist Dana Stern, who specializes in nail health, explains, "Nails derive oxygen and nutrients from the bloodstream and not the environment. [They] do not need to 'breathe' in the traditional sense." More importantly, Stern suggests that letting water molecules pass through polish may not be a good idea for nail health. "In general, water permeability with polish is not considered desirable as moisture entering the space between nails and polish can result in infection," she says. "An example of this is what salon technicians refer to as 'the greenies.' This common nail infection is a result of a green-pigment-producing bacteria called pseudomonas entering the nail, often in a space that is moist and not airtight."

Nail health isn't the only thing at stake for some breathable-polish fans. In the Islamic faith, for example, there is a common practice known as wudu, an ablution or cleansing performed before prayer. The appropriateness of wearing nail polish during prayer has been debated for a while in the Muslim community: Some people believe that nail polish interferes with wudu since the polish prevents water from penetrating to the surface of the nail, leading some Muslims to forgo manis or regularly remove their polish before prayers. (This can mean removing polish several times a day.) Obviously air- and water-permeable polishes aren't going to end that debate for good (a U.S.-based Islamic scholar declared the Inglot polishes permissible back in 2012, but the discussion continues.) It's possible that the added feature could help some people find a balance between beauty and faith. Any way you slice it, we call that a win.