Paint lifting with primer

[DPI]

I am replacing my K5 tailgate with a truck gate. I found the replacement gate from a salvage, but it was black. The paint seemed to be in decent but you can tell it was repainted from the original red. I filled a couple small dents and primed it with Nason primer/surfacer. After that I was block sanding it and found another small dent that I decided to fill. Upon sanding it down to fill I went down to the metal. The problem is when I went to spray the primer, the original paint started to lift where I feathered the paint edge. I sanded it down again, feathering the paint edge and tried to spray it again. The paint edge lifted again.

How do I keep the original paint edge from lifting from the primer?

 

[bigblock72]

You can try letting the primer dry for a couple of days, reblocking it and spraying light dry coats over the offending areas, the trick is to keep the solvents from attacking the paint so let it dry for a while between coats.

The best bet would be to strip the tailgate. Because even if you do get the lifting problem under control odds are the old paint is going to shrink and pull wrinkles and sand scratches within a month or two.

 

[DPI]

Thanks for the feedback. Can spraying the primer in cold weather cause it to never cure? It was likely in the lower 50s when I sprayed it.

What's the best way to strip it? I will likely end up doing that.

 

[bigblock72]

Catalized products don't cure very fast below 60 degrees, you need to get some heat on them for at least a few hours after spraying. The cold is probably making your lifting problem worse because the solvents are evaporating so slowly.

Aircraft stripper is probably your best bet for getting the old paint off, just be careful when you apply it. It's some mean stuff and will remove flesh faster than old cruddy paint. Make sure you wash and neutralize all the stripper after it has done it's job with lots of water if possible. It's best to prime the bare metal as soon as possible to prevent rust and contamination.

 

[ryoken]

hmmm, just saw this, good answers....

just to expand a little..

As was mentioned, catalyzed will dry slow, but it WILL cure at some point.. unlike some other scenarios...

In addition to post-heating, heating the substrate prior to application will help tremendously.. I bake my garage for 12 hrs prior to a paintjob.. shut it all down, wait an hr, turn the fan on for 15 minutes, and spray...

Always make sure to sand your bare steel before priming... sand, blow off, damp/dry with denatured, (metal conditioner at this point if you wanna be anal), zinc chromate or an equivalent self-etcher...