Mud cracking
Mud cracking turns up in 2 fields: corrosion, thermal spray. Here is what it means to the people in each one.
Mud cracking in corrosion
Network of cracks like dried mud in a coating applied too thick, typical of inorganic zinc and waterborne paints.
A coating defect in which the film shrinks as it cures and splits into an irregular pattern of plates, like a dried riverbed. It is most common with inorganic zinc primers and some waterborne coatings applied above their maximum film thickness, or cured too fast in heat and wind. Cracked areas lose adhesion and have to be removed and reapplied at the right thickness.
"Inorganic zinc went on at 7 mils in the corners and now it's mud cracking, sand it back and respray."
Mud cracking in thermal spray
A network of surface cracks that looks like dried mud, from tensile stress in a coating.
Random, interconnected crack pattern on the coating surface, caused when tensile stresses from cooling and shrinkage exceed the coating's strength. It is seen in thick or hot-sprayed ceramics, overheated fused coatings and some sealers. Unlike the controlled vertical cracks in DVC barriers, mud cracking is unplanned and opens paths for corrosive media to reach the substrate.
"Chrome oxide has mud cracking all over after the grind, somebody shot it way too thick and hot."