Cracking
Description : A series of deep cracks resembling mud cracks in a dry pond. Often in the form of three-legged stars and in no definite pattern, they are usually in the color coat and sometimes the undercoat as well.
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ORIGIN AND POTENTIAL CAUSES
» Excessive film thickness. Excessively thick topcoats magnify normal stresses
and strains which can result in cracking even under normal conditions.
» Materials not uniformly mixed
» Insufficient flash times between coats
» Incorrect use of additives
» Substrate is too hot or cold
» Use of coats incompatible
» Omitting the activator when mixing a 2K product -
PREVENTION TECHNIQUES
» Don’t pile on topcoats. Allow sufficient flash and drying time between coats
» Do not dry by fanning with compressed air from the spray gun
» Stir all pigmented undercoats and topcoats thoroughly
» Carefully read and follow
recommendations in the Technical Data Sheet(s). Additives not specifically
designed for a color coat may weaken the final paint film and make it more sensitive to cracking -
REMEDY
» The affected areas must be sanded to a smooth finish, or in extreme cases removed down to the bare metal, and a full refinish system reapplied