How long before paint problems show up?

B

BFLIT

If there are going to be issues with a paint job, such as solvent pop or other poor prep practices, how long before it will rear its ugly head? I have some parts that were painted (by someone else) well over a year ago and I want to use them. I only want to change the color. I bought them as part of a "parts car" for the car I'm working on. The guy started to paint but lost interest and sold me the whole car. The guy I bought it from had someone else paint them and he does not know what primers, paint, etc was used.They are in excellent shape and I do mean excellent, no dings, dents or waves. If I thought they needed body work I wouldn't hesitate to strip them. If I was not changing the color I would use them as is. On the rest of the car I am stripping to bare metal, priming, doing body work, then 2K primer, block sanding until good then finish paint. I hate to take a perfectly good metal part down to bare metal if I don't need to. I have had these parts in my shop for over a year and they look just as good as the day I got them.

I don't know if the paint is single or two stage. If the forum consense is to strip to bare metal I will but I will be crying the whole time. It will be very hard for me to destroy a beautiful paint job.

If the forum thinks I can get away with light sanding and proceeding, please let me know what should be the next step. Sanding grit? Epoxy seal coat? then final color? I am not blending any parts. The entire car will be painted at the same time when I get that far. Yes, I'm using all SPI products.

There are 6 pieces, 2 large rear fenders and 2 fender extentions(it's and old car) and 2 fender skirts. I would be saving a considerable amount of body work/prep time if I can light sand and go.

As I said they have been inside my shop, dry and clean, for a year. Do you think if I let them sit outside in the sun for a month issues may show up?

All opinions are appreciated. Be honest, I can take it!
 
If they look that good and were painted recently, they are probably single stage or base clear. You will have to sand them to paint over them anyway, so sand a little and see if the dust is white, or paint color.

Here is the biggest question: Is it worth the risk to YOU. What color are you going to make it? If I was painting it with a relatively inexpensive solid color, I'd definitely chance it (if it was my own and there were not signs of shoddy work)). If your base is really expensive, or you're doing custom air brush work or stripes, it may not be worth the risk to you.
 
There is no set time, to answer your question.
2 hours to 10 years and everywhere in between, just depends where it is coming from.
Examples:
Solvent trapped in first coat of base 3-5 days.
Solvent trapped in first coat of clear 3 hours or overnight.
Using acid etch primer on bare metal, 1 year to 8 years.
Painting over lacquer, first day in sun to 5 years.
3rd paint job on corvette, 3 days of sun til 6 months.
Extreme solvent trap in base, peeling in 3 months to 2 years.

The list goes on and on.
 
Thanks guys. All that makes sense. I'll be firing up the DA sander soon, and crying the whole time. But as Strum456 pointed out, better to cry now than cry later.
 
i would lay them in the sun for as long as possible before redoing them. you can always remove them later. something to think about.
 
shine;32187 said:
i would lay them in the sun for as long as possible before redoing them. you can always remove them later. something to think about.
Click to expand...

This is a very good point! If the car has not been driven, NOTHING should be done until the car has had at least seven full days in sun, even if paint job is six months old, no sun, no cure.
 
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