Cracks in paint - and do I need to prime old colour?

[75nut]

Recently paint some areas of my Alfa.

They looked fine after painting, I zinc primed, filler primed, rubbed down, normal primed, rubber down and then color coated.
Coming back to the car today (after it sitting for about 3 or 4 months and there are a load of cracks in the paint.

Other areas I did are fine.

Did I let it dry to quick , too slow? Do you think I laid coats on too thick? It was painted outside by the way on warmish days.

I also have another Alfa with flaking lacquer and pink paint (rather than the red it should be), I'm going to sand of the lacquer but do I need to prime a keyed colour or can I spray new colour straight on top?

All help appreciated!

[bobman]

Paint cracking is usually caused by primer/paint not being fully cured/dry when over coated, although build up/too much material, not being properly mixed and stirred can also cause it, hard to say without pics

[75nut]

Cheers Bobman

[75nut]

Do I need to prime over flatted back old paint then or can I put colour straight on?

[bobman]

Jun 4, 2014 19:57:18 GMT 75nut said:

Do I need to prime over flatted back old paint then or can I put colour straight on?

I have a ke70 in at the min, one of the rear doors was covered in cracks as the owner described Chinese writing,

I flatted back with p120 on the da and then hit it with some 2k high build witch I flatted back with p800 then coloured and cleared, jobs a good un!.While painting it on my 2nd coat on the 1/4 I noticed the start of some reactions so stopped and put the heater on, then when dry I flatted back the area with p800/1200 then pre-clean an re-applied my colour and then shot the lot with clear, So again it depends on the job in hand/hard to say without seeing it but usually best to prime and start again IMO