What is alligatoring in paint?

Alligatoring is a cracking pattern that resembles alligator skin. It usually develops when an old coating becomes hard and brittle, when incompatible coats are applied over one another, or when a topcoat dries and moves differently from the layer beneath it. Remove loose and cracked coating, sand back to a sound edge, correct any compatibility problem, prime where required and repaint with a compatible system.