Wondering whether to buy your acetone at the beauty supply or the hardware store? The fact is, acetone is acetone, but some acetone contains small amounts of other impurities, says Doug Schoon, president of Schoon Scientific and co-chair of the Nail Manufacturers Council on Safety. He explains: “For removing nail polish or coatings, the impurities usually don’t matter since their concentrations are so low. However, when acetone is used to clean the nail plate for better adhesion, the impurities left behind when the acetone evaporates are often oily, which can make a big difference. Leaving small amounts of oily contaminants on the nail plate is the opposite of what acetone is supposed to do when the nail plate is being prepped for a nail coating. Acetone is supposed to remove oily contaminants on the surface of the nail plate for better adhesion.”

It is true that hardware store acetone is usually more contaminated than the acetone that is purchased in a pharmacy or beauty supply. “Nail techs should use at least 99% acetone, but some sell poor grade acetone that is mislabeled as 100% acetone, when it is not,” says Schoon. Therefore, Schoon recommends that you test the grade you purchase to ensure it does not contain oily contaminants. This can be done safely, if you take appropriate care.

He recommends using the following technique: Fill a shot glass almost full with acetone, loosely cover the shot glass with a piece of photocopy paper, then set it somewhere to allow the acetone to “safely” evaporate. In other words, keep this shot glass and any other acetone that you use away from all sources of excessive heat and avoid all sparks or flames to prevent a fire. If this is done, within a week the acetone should completely evaporate. Then rub your finger inside the shot glass. If you feel any oily residue, that suggests the acetone is likely not suitable for cleaning the nail plate since the oil can disrupt adhesion. “This is why I recommend using a professional nail cleanser to ensure the plate is properly cleaned,” says Schoon.