(E) Mud-Cracking

Identification:

The failure is named as mud-cracking as it resembles the pattern of cracked mud. Cracks are developed throughout the coating and penetrates the substrate. In appearance, it is similar to alligatoring.   

Description:

This problem is mostly confined to water based epoxy coatings in which the resin is distributed in the form of fine droplets of water. If the evaporation rate is fast enough, residues of binder are left which donot bind together and wet the pigments. The pigment looks like a mud when the water dries out from it. This failure is serious as it reaches the substrate.

Prevention:

• Apply thin coatings.

• Do not apply highly filled waterborne coatings if the environment promotes fast drying of the coating.

• Use reinforcing pigments.

• Use of appropriate pigment/binder rate.