Crackle nail polish has a specific formulation that causes it to split and crack as it dries. This effect is typically achieved through a combination of ingredients and a specific application technique. The base coat underneath the crackle polish needs to be completely dry, and the crackle polish is applied in a thin layer. As the crackle polish dries, it shrinks at a different rate than the base coat, causing it to crack and reveal the color underneath.
While some nail polishes may contain alcohol as a solvent, it is not the primary ingredient responsible for the crackling effect in crackle nail polish.