A crackle nail polish is unique in the way it shows your nails off. The way to use this form of nail polish is to first apply a regular coat of nail paint and then apply a coat of the crackle polish on the base. The final step is to apply a final coat with a clear polish. As the crackle nail polish dries, it shrinks and cracks, thus showing the base in different parts of your nail. The result is a two-toned pattern on your nail that is naturally unique.