Definition - What does Cracking mean?
Cracking refers to a type of coating defect that is characterized by the chipping away of the applied paint film in small sections or entirely. This results in the exposure of the substrate metal to corrosion causing agents and eventual degradation.
Corrosionpedia explains Cracking
Cracking of paint coatings is often caused by the inappropriate application of protective paint components - including fillers, resin and primers.
A sporadically timed application of the paint may also lead to cracking. When a portion of the metal is painted at one time, with a corresponding film thickness and application style, then problems such as cracking may occur after the remainer of the metal is painted with alternative application philosophies.
In addition, an inappropriate coating and metal pairing is a major cause of cracking.
Paint cracking is visible on both exterior and interior areas; both occur after long atmospheric exposure.