As you may know, acrylic nails are created using a mix of acrylic powder (polymer) and a liquid called a monomer. The molecules of the powder and monomer form a bond to create a solid structure that will serve as your artificial nail. Acrylic powders differ across the board due to different blends that companies use in their formula, but there are two standard types of monomer available: EMA (ethyl methacrylate) and MMA (methyl methacrylate).

Methyl methacrylate (MMA) in liquid form is a substance regarded by FDA’s Office of Cosmetics and Colors as “a poisonous and deleterious substance,” which is why it was made illegal for use. When used during a nail service, it can cause yellowing of the natural nails, air blockages, and irritation and numbness of the cuticles and the skin around the nail. Nails made with MMA are rock hard and usually shrink slightly when they set, which is why sometimes your nail beds will feel very tight when you get acrylics. MMA liquid is commonly used as dental acrylic for crowns and bridges, and is made to be as hard as bone—this is why most sets made with MMA last somewhere between two to six weeks. Yes, they last long and are virtually unbreakable, but the bond between your natural nail and the acrylic is so strong that when they do break, it’ll hurt like no other and take your natural nail off as well. 

Ethyl methacrylate (EMA) is a substance that has the same purpose and does the same job as MMA liquid, and its use has been approved by the Cosmetic Ingredient Review in 1999. Although not as sturdy and durable as MMA acrylics, EMA helps the nail enhancement to be much more flexible, and therefore becomes more prone to lifting. However, an EMA acrylic set feels much more comfortable than MMA acrylics. A full set of EMA acrylic nails will last you two to four weeks if taken care of and are properly fitted to your nail, as compared to the four to six weeks with MMA. It’s a lot easier to get fills more often (twice a month instead of once) than it is to wait for a nail that was ripped off with your acrylics to grow back to its normal length—if that’s the only damage you get.