Really need a paint expert!
#31
04-09-2014, 10:03 PM
A few questions..........
Are the surfaces that are cratering primed or just scuffed old paint? And if you're shooting primer or sealer are they reacting at all when they're shot. Did you start with bare metal and build up your foundation with epoxy on the bare metal then primer surfacer and then top coat....and was there any reaction with any of those applications.
If you're shooting over old paint and it keeps cratering even though you've cleaned it and done everything to make sure it's clean then the old paint probably was treated with fish eye eliminator and your only option would be to strip it to bare metal and start over or........introduce fish eye eliminator to your paint (which I personally wouldn't do).
The unfortunate thing about these kind of problems is that they may go away without you being able to figure out what caused them.
I'm inclined to think that you may be taking the contamination to the panels even while you're cleaning them. Example.......if you're wearing a fish eye causing antiperspirant you would actually be recontaminating the surface as you wipe the panels down.
Just some things to consider. I would really like to know what is causing the fish eyes if you manage figure it out.
Are the surfaces that are cratering primed or just scuffed old paint? And if you're shooting primer or sealer are they reacting at all when they're shot. Did you start with bare metal and build up your foundation with epoxy on the bare metal then primer surfacer and then top coat....and was there any reaction with any of those applications.
If you're shooting over old paint and it keeps cratering even though you've cleaned it and done everything to make sure it's clean then the old paint probably was treated with fish eye eliminator and your only option would be to strip it to bare metal and start over or........introduce fish eye eliminator to your paint (which I personally wouldn't do).
The unfortunate thing about these kind of problems is that they may go away without you being able to figure out what caused them.
I'm inclined to think that you may be taking the contamination to the panels even while you're cleaning them. Example.......if you're wearing a fish eye causing antiperspirant you would actually be recontaminating the surface as you wipe the panels down.
Just some things to consider. I would really like to know what is causing the fish eyes if you manage figure it out.
I started with bare metal (either sand blasted or hand stripped) that was epoxy primed, filled and blocked where needed, then multiple 2k prime and long board and finally wet sanded with 400. I never had any signs of cratering until after I wet sanded. I believe as I indicated in an earlier post that one of the rags that I used keeping the surfaces wet while wet sanding had gotten cross contaminated from being washed with other rags. The cratering showed up when I tried to shoot color. All that said, I think that I just can't completely clean the contamination, which I believe to be silicone, out of the primer.
This will go down as a huge lesson learned.
Do you have a recommendation for a paint stripper that will not also lift the filler?
#32
04-09-2014, 10:14 PM
There's no chemical strippers that i know of that won't contaminate everything. If you think you've got problems now with fisheyes, try putting paint over the top of paint stripper. personally, I would machine sand everything you need to strip. That way you know what you have, and where you need to go. To do it quickly, I'd use what we call a whiz pad, which is an 8" sanding pad on a circular buffer/grinder (not an oscillating or DA type) and 36 or 40 grit round sandpaper discs. It makes pretty quick work of removing paint and materials.
#33
04-09-2014, 10:56 PM
I have to admit that I am a bit reluctant to be aggressive on the hood. I have used I think what you call a whiz pad on rough fiberglass on a boat. It was/is a good straight hood. It has very little filler. The doors do have filler, one in particular. On the doors, I will sandblast all but the big "flat" outer panels and I guess that maybe 80 grit on a DA in those areas since I would like to try and save the blocked shape of the filled areas.. I originally chem stripped the "flat" areas of the hood, both top and underside and sandblasted the edges. I never had problems with primer until after wet sanding when I believe I contaminated the surface.
#34
04-10-2014, 04:57 PM
Well, the doors are back to mostly bare steel. I DA'ed the large outside "flat" areas and sandblasted the rest. I think that I have retained the blocked flat filler but removed the primer. I took it to my friends booth. I will do a little filler tune up in the AM and prime in the PM. I was here a long time ago on these doors. I hate this level of rework!
#35
04-11-2014, 06:21 PM
Cargo Master
#36
04-11-2014, 06:36 PM
The fisheye in the hood imho was too severe to be oil in the air supply. Based on where it was and how I wet sanded the underside of the hood, silicone contamination from one of the rags when wet sanding is what makes sense. Yesterday I stripped the doors and today I blocked the doors and got them back into prime. I am gun shy to work in my shop so I worked outside yesterday and then in my friends paint booth today to shoot the primer. I am going to work the doors at his shop all the way through color. Stripping the doors yesterday was a giant step backward!
#39
04-30-2014, 09:01 PM
A tough lesson learned allowing DOT 5 into my shop.
#40
04-30-2014, 09:42 PM
Drew, I brought the doors back into final color after sandblasting the jams and inside of the doors and then using a DA on the outer flater surface. No problems but the cure was not trivial. I will have to strip the hood and running board top surfaces back to bare metal. I am pretty sure that I used a rag when wet sanding that became contaminated with DOT 5 by washing several rags together one of which I think I wiped up some brake fluid, careless.
A tough lesson learned allowing DOT 5 into my shop.
A tough lesson learned allowing DOT 5 into my shop.
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