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First, the good news. My '68 is all the same color! It's been a year and a half of work, but I've finally achieved that milestone, and it feels great. I put 2 coats of 2k, which I'll guide coat and block. Then more 2k to wet sand. Then... paint!
I have 2 questions, though. First, after the primer, I can see that my replacement front clip has some lines in it that look a little like stress lines (but maybe not), though the fiberglass seemed ok. It's hard to see in the second picture, but is in the middle of the pic.
Second, I have a couple places where my filler had a divot that I missed (see the third pic). What's the best way to fill these? Do I just use some polyester filler over the 2k and sand it flat? I've been super careful this whole process and want to make sure that's the best way to go before I touch anything.
Are the "lines" over a joint line? They might be thermal in nature, bonding joint failure or excessive thickness of primer causing contraction. That area may have to be redone. The void can be filled as you thought and then resprayed and block sanded.
Are the "lines" over a joint line? They might be thermal in nature, bonding joint failure or excessive thickness of primer causing contraction. That area may have to be redone. The void can be filled as you thought and then resprayed and block sanded.
No, they aren't over any bonding strips (it's a used one-piece repro). They don't radiate from an inside corner like I'd expect stress lines to, but have that same kind of spiderweb pattern to them. I don't think they are from the primer being too thick since I noticed them in the first coat. If they were stress marks, how would I treat them? Better safe than sorry.
Hi E.M,
I really know very little about prepping for paint.
But regarding your first question I do think that you should have stopped with the primer as soon as you saw signs of these marks in the first coat.
I think you need to get back down to the fiberglass in those areas to determine what their CAUSE is and thus what the PROPER fix is.
I'm sorry! I realize this isn't what you want to read!
What preparation did you do to the one piece before you started with primer?
Regards,
Alan
Hi E.M,
I really know very little about prepping for paint.
But regarding your first question I do think that you should have stopped with the primer as soon as you saw signs of these marks in the first coat.
I think you need to get back down to the fiberglass in those areas to determine what their CAUSE is and thus what the PROPER fix is.
I'm sorry! I realize this isn't what you want to read!
What preparation did you do to the one piece before you started with primer?
Regards,
Alan
I considered shutting everything down when I saw the first lines, but decided to go ahead since everything was already mixed and prepped. If it's a matter of "they'll go away when you block" then I'll just keep moving. But if they're just going to reappear in the basecoat... that's not cool. But I don't mind re-doing if it will give me the end result I'm looking for.
As far as the prep, I stripped the entire car (all razor blade and sanding - no chemical stripper). After several minor fiberglass repairs, I went over the whole thing with a skim coat of polyester and sanded with 120 grit.
Now that you mention it, though, the only part of the car that didn't get the polyester was the section around the headlights... which is the only place I remember seeing the lines. There aren't any big enough areas to worry about overall level-ness in that section (and I was thoroughly sick of sanding filler), so I just skipped the filler there. I'll check tonight and see if the lines only appear there. I only saw them two places when priming, but it was late last night when I was finishing my 13-hour stint in the garage...
Can't tell much from the photos, but are these 'lines' in the corners of the headlamp opening and radiating away from the corner? If so, these are very common stress cracks and need to be reinforced from the underside...before doing the prep work. That said, since the prep has been done already, you should only have to repair those areas.
Ignore this post if your 'lines' are not what I am describing.
________________________
Great work, so far. But, it's important to step back and make sure any 'blemishes' get diagnosed and repaired properly before proceeding.
Do I need to use a hardened filler, or will a tube of that Bondo glazing putty be ok?
Always use two part filler. The glazing putty is just thick lacquer primer. Old technology. Over time the putty will shrink into the void which will come back to haunt you. Usually it's not noticed it till after the Vette is painted. It cause's Read Through or Mapping.
Do I need to use a hardened filler, or will a tube of that Bondo glazing putty be ok?
I like the polyester filler better than glazing for something that size. Reserve the glazing for the very smallest and finest of imperfections (pinholes for example). Reprime w 2k after use of either. Fwiw, I agree with Alan 71...something is/has caused the lines...get it now, not later. I'd let it sit a week or two after you think you're done, preferably in hot sun, under no trees and see if anything rears its ugly head. The 2k is stable and won't absorb moisture like the one part primers of yesteryear.
Last edited by jimvette999; Jan 3, 2017 at 08:28 PM.
I got a little better picture last night. I have three spots like this, all on the front clip where I didn't use any polyester filler. It looks like crazing in the gelcoat. I don't see anything amiss on the underside. Is that possible? If so, what's the best plan?
Are those "ripples", or a photographic artifact ? Can you feel the lines, or just see them? If those are the only areas that have this defect, it could be delamination or some other adhesion issue. What you don't want to do is shoot the color over this area. I'd take it down to the glass in these spots. Doing so could save a lot of heartache in the future.
It's hard for anybody to say what the problem is or what to do about it without actually seeing it but many times a defect might appear in the fresh primer and not cause a problem unless you can see an uneven surface or something rising up. You can wait for it to cure for a few days , scuff and recoat the area. If it doesn't re-appear you should be alright. As to using filler putty over the primer . Also let it cure a few days and scuff with a fine pad or wet sand lightly before applying the two part polyester spot putty. Fresh primer often will appear to show defects that will wet sand out and not create any problems providing that the primer is cured well before top coating..
I would have suggested Epoxy primer to seal up any extensive body work,
then use 2k primer for build/flatness.
I would agree. I didn't do any extensive body work, though. A few minor repairs (none more than an inch or so). I did epoxy all the metal first.
Any thoughts on the lines?
I considered shutting everything down when I saw the first lines, but decided to go ahead since everything was already mixed and prepped. If it's a matter of "they'll go away when you block" then I'll just keep moving. But if they're just going to reappear in the basecoat... that's not cool. But I don't mind re-doing if it will give me the end result I'm looking for.
As far as the prep, I stripped the entire car (all razor blade and sanding - no chemical stripper). After several minor fiberglass repairs, I went over the whole thing with a skim coat of polyester and sanded with 120 grit.
Now that you mention it, though, the only part of the car that didn't get the polyester was the section around the headlights... which is the only place I remember seeing the lines. There aren't any big enough areas to worry about overall level-ness in that section (and I was thoroughly sick of sanding filler), so I just skipped the filler there. I'll check tonight and see if the lines only appear there. I only saw them two places when priming, but it was late last night when I was finishing my 13-hour stint in the garage...
So, did you sand the whole body with 120 grit and then spray the primer over the 120 grit sanded body?
So, did you sand the whole body with 120 grit and then spray the primer over the 120 grit sanded body?
Yes. It was probably a little coarser than it had to be, but since I'm blocking two coats then shooting more I didn't see a reason to take the time to go over it with a finer grit.
To be safe, I'm going to sand down to the glass in the areas with lines, then shoot epoxy, then re-do the 2k. I've got too many hours in the car to take risks. Better safe than sorry...
Questions on primer
