This is often a result of improper drying between coats of finish. Drastic temperature changes during the drying/curing process may also result in cracking. Incompatible materials and insufficient mixing of product are additional sources of cracking. However, the most common cause of cracking is that the coats applied are too heavy. Always allow for proper drying between coats, mix products thoroughly before applying, avoid application of heavy coats of finish and use products within the same system. It is often best if they are supplied from the same manufacturer.