Paint is cracking and showing lines, like dried mud

Question

4 years ago, after repainting my 1980 Chrysler LeBaron, I'm seeing many lines appear in the paint. These lines appear all over, but especially around corners, and much more on flat, upright facing surfaces, not really on the sides. This leads me to believe it may have something to do with being in the sun a lot.

We repainted it the original color, with the original paint, and used commercial grade clear coat. The paint was applied by a friend whose day job is as a body mechanic, though not usually painting, though he had experience.

Waxing masks the lines for a short period, but then they become visible again after a few weeks. It only seems like I am seeing more and more of them. They are not scratches- there are far too many and I'm protective of things being set on my car.

What is causing this?

Is there anything I can do to prevent more of these lines from coming?

Is there anything I can do to "erase" the existing lines?

Answer 1

This looks like textbook cracking. This is a failure that can be caused by a myriad of sources, from chemical incompatability of paint and clearcoat to improperly applied paint. Your friend's inexperience with painting might be the root cause. Four years is a long time for a poorly applied clearcoat job to start showing issues, it could be something else.

Taken from the Sherwin-Williams Automotive Paint Troubleshooting Guide (PDF, page 19):

CRACKING (Checking, Crazing, Spitting, Alligatoring, Crowsfeet)

Cracks or lines of various lengths and widths in the topcoat finish often resembling the cracking of dried mud.

CAUSE:

• (A) Excessive film thickness of the undercoat and/or topcoat.
• (B) Refinishing over a previously crazed/cracked surface.
• (C) Insufficient flash time between coats and/or force drying undercoats using air from the spray gun.
• (D) Mixing incorrectly or using too much hardener.
• (E) Paint ingredients not thoroughly stirred or agitated.
• (F) Breakdown of finish due to prolonged exposure to sunlight, moisture, and extreme temperature changes.
• (G) Using generic reducers and/or hardeners.

REPAIR

• Remove all cracked paint film and refinish.

PREVENTION

• (A) Apply all materials following label direction.
• (B) Completely remove crazed/cracked finishes before refinishing.
• (C) Do not force dry undercoats by fanning with spray gun air.
• (D) Mix ingredients thoroughly using the recommended additives. Add each component in proper sequence following the recommended mixing ratio.
• (E) Stir or agitate materials thoroughly before use to ensure all ingredients are in solution.
• (F) Use premium two component undercoat and topcoat system to provide maximum gloss and durability.
• (G) Use the recommended thinner/reducer and hardener, and then measure accurately.

Examples:

Fundamentally, what is happening is your paint is shrinking. It's shrunken to the point where visible gaps are showing up between the pieces of paint still there. There's a lot of causes, and since it held up for several years it's likely to be environmental more than a poor application of paint.

Your permanent recourse is take it all off and put new stuff on.