Cracking paint: should I shoot thinner?

[Braukuche]

I’ve been painting cars as a hobby for years now. I’ve always used single stage, always shot three good coats sometimes four thinking it’s better to have more material for color sanding and buffing than less. But I’m starting to rethink that.
I’ve always notIced many shops shoot what I always considered to be thin jobs, as do many auto manufacturers. I thought it was to save a buck, but over the past year I’ve noticed that in a few spots the paint has cracked on a couple of my cars. Others the paint is fine after many years.
Now, I park my cars outside, some covered some not. They get sun, cold, wet, etc. the cracks showed up after about one year in some cases five.
So, is my use of multiple thick coats the cause or could I be doing something else wrong?
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Go Reds! Smash state!

Retirement is here!
1956 Ghia
1959 SO-23 Westfalia
1960 double cab
1960 Baja Bug
1963 stretched double cab
1962 Golde sunroof Ghia
1963 356 B coupe
1963 Notchback
1967 21 window less rusty now

[wheel607]

Maybe waiting too long between coats. Not sanding when you wait too long. More coats have to be done when paint is tacky.....not when it is dry. All I know is that I have shot multiple coats of single stage (while it is still wet) with no problems as you are having. I usually use multiple thin coats, about 3-4 times around the VW.

[Tvättbjörn]

Possibly wrong ratio of paint, hardener, reducer/ thinner. Cheap / low quality paint will do the same.

[E-boyz67]

Bottom line, single stage is really old technology. It’s cheap and as you can see not so durable. A paint job should have max of 11-12 mils. Any more and you get what you get(crackling). Quality paint is well worth it in the long run. There’s lots of quality paint systems to use but remember you get what you pay for. I use Sikkens for many years.
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[E-boyz67]

Forgot to mention strip down to bare metal if no body work is not needed then treat Al bare metal, apply epoxy primer then paint. Hi
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