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.
Heard on the job
Inorganic zinc went on at 7 mils in the corners and now it's mud cracking, sand it back and respray.
Also heard as
- mudcracking
Related terms
Zinc-rich primer
Primer loaded with zinc dust that protects steel galvanically as well as acting as a barrier.
DFT
Dry film thickness: the thickness of a cured coating layer, measured in mils or microns.
Stripe coat
Extra coat brushed onto edges, welds, bolts and corners to build thickness where spray runs thin.