Craquelure

Etymology

From French "craquelure," from craqueler, "to crack," from craquer, "to crack," a word imitating the sound of splitting. It names the crackle pattern that develops as layers of paint and varnish dry, shrink, and age at different rates. Because the pattern is hard to fake convincingly, it is a favorite test of authenticity.

noun · /krak-luur/
The fine network of cracks that forms in the varnish or paint of an aging picture.
What it names
The delicate web of hairline fractures across an old master’s surface — a mark of genuine age that conservators and forgers alike study, giving you a precise word for the crackle of time.
Example
Experts grew suspicious when the craquelure ran in a suspiciously even grid — real age cracks more randomly than that.
Related idea
Craquelure is the accidental crack pattern of aging; crackle glaze is a similar-looking effect deliberately induced by potters as decoration.