Gel nail polish is a special type of nail polish that differs from classic nail polish mainly in the way it dries. Unlike conventional nail polish, which dries in the air, gel polish requires a special UV or LED lamp to cure. Each layer applied, whether it is a base coat, coloured gel polish or top coat, must be cured separately in this lamp. This polymerisation process, which is a chemical reaction triggered by light, gives the varnish a high level of scratch and abrasion resistance. The result is a manicure that retains its appearance and high gloss for several weeks without flaking. After some layers have cured, a sticky layer known as 'efflorescence' may remain on the surface, which is wiped off with a special product. The removal of gel coat is also different, it cannot be washed off with ordinary polish remover. It requires either disturbing the surface with a file and then wrapping the nail in a product with acetone, or sanding it off completely.