Paint question on rear spoiler

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Joined
Jan 13, 2012
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Washington
My Car
1971 Mach1, 351 Cleveland, Ram Air (not factory), C6 Automatic, AM/8 Track, Bright Red.
I have an original rear spoiler that no matter what I do I keep having bubbles that show up, it's not the paint rising it's the fiberglass bubbling. I've tried everything including sanding all the paint off then resurfacing areas with fiberglass repair to insure it's super smooth. After a few months the fiberglass bubbles appear again, it seems to happen when the car has been parked in the sun for a while on a hot day. I've redone it I believe 3 times and a had a paint shop do it once, but the bubbles keep coming back in the same spot. Any suggestions would be appreciated.

Bubbles.JPG

 
I have an original rear spoiler that no matter what I do I keep having bubbles that show up, it's not the paint rising it's the fiberglass bubbling. I've tried everything including sanding all the paint off then resurfacing areas with fiberglass repair to insure it's super smooth. After a few months the fiberglass bubbles appear again, it seems to happen when the car has been parked in the sun for a while on a hot day. I've redone it I believe 3 times and a had a paint shop do it once, but the bubbles keep coming back in the same spot. Any suggestions would be appreciated.
Have you tried literally grinding out the entire bad spots? It could be that there is moisture inside the skin that has not been removed. It may take digging in there to remove all the affected material, then carefully rebuilding the surface. I had a similar issue on a prototype I was building. Getting tough with it fixed it in the end. I'm NOT saying this IS the problem, but if moisture is present within the skin, it could be the cause for it returning time and time again. Just a thought, others may have different ideas.

 
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Hi Jim,

What Geoff and Mark have said so far is good advice. As i see it, basically you have two major options here to choose from. The first option is to keep on persevering with trying to remedy and repair your existing spoiler.The second is to cut your losses, and buy a new fiberglass spoiler and refinish it to your liking. There are arguments for both options, and you will have to decide which one is best for you. It really comes down to a money thing here.

You have been faced with a blistering or bubble problem on your fiberglass spoiler. That is a fairly common problem with fiberglass itself. Fiberglass can be a bitch of a material, and play up badly sometimes.This can be from moisture probs or gel coat pobs. I won't get technical here. You say that you have made 3 attempts yourself to try and fix the problem, and your paint shop has had a go once but failed as well to fix the problem as it keeps on coming back. When you look at that from a labor and materials perspective, eg, a cost perspective, i'm sure that you have thrown a fair bit of money trying to rectify this problem.

But the overall news is not good for you, because the reality is, that you can try and have another attempt at fixing this problem, throw even more money at it, but unfortunately, there will be no guarantee that the problem will not come back again. The initial cost to buy the spoiler, plus all this extra money you are putting into it, gets out of hand. On that basis, sometimes it pays just to cut your losses and start again with a new, good quality fiberglass spoiler, and refinish it to your own taste.

I can give you technical advice on trying to fix your blistering problem, but i can't guarantee that will completely solve your problem, and the blisters will never come back. The basic tech advice is as follows. First up, you don't mix two pack paints with acrylic lacquer paints, or to be more specific, you can't put two pack paints over lacquer paints. What paints have you been using so far to try and fix the spoiler? Also, have you or your spray shop attempted to back gouge out where the bubbles are, and back fill in the holes or depressions left behind?

My attack on the bubbles would be to first, sand down to the fiberglass level around the bubble areas. Next carve or gouge out the fiberglass bubbles well into the glass layer. Next, and with the glass being super dry, spray two or three good coats of epoxy primer on those spots and surrounding raw fiberglass areas. This seals the fiberglass surface off, and gives you a good sound base to work from here. Next, scuff dry the epoxy primer, and back fill in the holes with a two pack wiping putty. I would choose a product that has aluminium mixed in with the putty. This type of product is used for repairing metal rust holes, and cures out very hard. Sand the filler down level, and apply another two coats of epoxy primer over the repair spot areas. Lightly scuff down that primer dry, and then prepare the rest of the spoiler for priming the whole thing with three or four coats of standard 2 pack urethane primer/ filler. Sand that down when cured, and then move into your top black color coats. You can choose to use a 2 Pack mat or satin black paint here, or you can use a mat or satin black acrylic lacquer as an option. I like using a lacquer, as i don't end up getting any nibs in the paint finish at the end. With lacquer, i can remove all nibs on the fly, and get a nib free finish - with 2 pack, you can't do that.

Remember, if you have lacquer black paint on your spoiler now to start off with, you can't apply any 2pack or epoxy paints over the lacquer paint. If you need any more detailed tech info, PM me.

Hope all that helps make up your mind on which way you want to go.

Thanks,

Greg.:)

 
I don't know why your having this problem but I think I would just cut my losses and buy another wing and if it were me I would shop around and find an original Ford piece at a swap meet. I've seen plenty of them at Ford Carlisle and at other swap meets. The original Ford wings seem to have better quality and in my opinion look better on the car. I know many people are going to disagree with my last comment so I will end this by saying it's just my opinion and we're all entitled to that.:)

 
Have you tried literally grinding out the entire bad spots? It could be that there is moisture inside the skin that has not been removed. It may take digging in there to remove all the affected material, then carefully rebuilding the surface. I had a similar issue on a prototype I was building. Getting tough with it fixed it in the end. I'm NOT saying this IS the problem, but if moisture is present within the skin, it could be the cause for it returning time and time again. Just a thought, others may have different ideas.

Yep, grinded them down smooth, really didn't dig out any out though, that may be the solution, thanks

 
Hi Jim,

What Geoff and Mark have said so far is good advice. As i see it, basically you have two major options here to choose from. The first option is to keep on persevering with trying to remedy and repair your existing spoiler.The second is to cut your losses, and buy a new fiberglass spoiler and refinish it to your liking. There are arguments for both options, and you will have to decide which one is best for you. It really comes down to a money thing here.

You have been faced with a blistering or bubble problem on your fiberglass spoiler. That is a fairly common problem with fiberglass itself. Fiberglass can be a bitch of a material, and play up badly sometimes.This can be from moisture probs or gel coat pobs. I won't get technical here. You say that you have made 3 attempts yourself to try and fix the problem, and your paint shop has had a go once but failed as well to fix the problem as it keeps on coming back. When you look at that from a labor and materials perspective, eg, a cost perspective, i'm sure that you have thrown a fair bit of money trying to rectify this problem.

But the overall news is not good for you, because the reality is, that you can try and have another attempt at fixing this problem, throw even more money at it, but unfortunately, there will be no guarantee that the problem will not come back again. The initial cost to buy the spoiler, plus all this extra money you are putting into it, gets out of hand. On that basis, sometimes it pays just to cut your losses and start again with a new, good quality fiberglass spoiler, and refinish it to your own taste.

I can give you technical advice on trying to fix your blistering problem, but i can't guarantee that will completely solve your problem, and the blisters will never come back. The basic tech advice is as follows. First up, you don't mix two pack paints with acrylic lacquer paints, or to be more specific, you can't put two pack paints over lacquer paints. What paints have you been using so far to try and fix the spoiler? Also, have you or your spray shop attempted to back gouge out where the bubbles are, and back fill in the holes or depressions left behind?

My attack on the bubbles would be to first, sand down to the fiberglass level around the bubble areas. Next carve or gouge out the fiberglass bubbles well into the glass layer. Next, and with the glass being super dry, spray two or three good coats of epoxy primer on those spots and surrounding raw fiberglass areas. This seals the fiberglass surface off, and gives you a good sound base to work from here. Next, scuff dry the epoxy primer, and back fill in the holes with a two pack wiping putty. I would choose a product that has aluminium mixed in with the putty. This type of product is used for repairing metal rust holes, and cures out very hard. Sand the filler down level, and apply another two coats of epoxy primer over the repair spot areas. Lightly scuff down that primer dry, and then prepare the rest of the spoiler for priming the whole thing with three or four coats of standard 2 pack urethane primer/ filler. Sand that down when cured, and then move into your top black color coats. You can choose to use a 2 Pack mat or satin black paint here, or you can use a mat or satin black acrylic lacquer as an option. I like using a lacquer, as i don't end up getting any nibs in the paint finish at the end. With lacquer, i can remove all nibs on the fly, and get a nib free finish - with 2 pack, you can't do that.

Remember, if you have lacquer black paint on your spoiler now to start off with, you can't apply any 2pack or epoxy paints over the lacquer paint. If you need any more detailed tech info, PM me.

Hope all that helps make up your mind on which way you want to go.

Thanks,

Greg.:)

Really great advice Greg, thanks for taking the time to go into such details, it's what makes this site so great. As far money invested in doing the repairs myself, it's primarily just my time except when I had a paint shop do it. It lasted longer than my repaint but they still came back. I may use some tough love on it and really dig those areas out and give it one last try following your instructions. I've PM'ed a local member who has a couple for sale to check those out. Thanks!

 
Well Jim, you've got very good advice from Greg especially and from others.

As for replacing the spoiler, absolutely get an original. I've seem too many reproductions at shows that are totally the wrong shape.

Don't throw out the old one if it is an original. You might just feel like playing with it again in the future and if you do manage to fix it, you could the sell it and recoup some of your loss.

 
My approach would be a little different concerning the bubbles or blisters. I would literately drill out the blisters all the way through then fill plug with fiberall. It's apparent there's a issue with the fiberglass in that area and gouging sanding etc isn't working. It needs to be removed.

http://www.autobodytoolmart.com/u-pol-fibral-sandable-glass-fiber-paste-p-15131.aspx?gclid=CKyV1KWXmNECFYZMDQodEtUH7A
Thanks, I'll give it a try, nothing to lose and the car is parked until Spring. I'd like to try and savage this one since it's been riding on the trunk for 45 years.

 
My approach would be a little different concerning the bubbles or blisters. I would literately drill out the blisters all the way through then fill plug with fiberall. It's apparent there's a issue with the fiberglass in that area and gouging sanding etc isn't working. It needs to be removed.

http://www.autobodytoolmart.com/u-pol-fibral-sandable-glass-fiber-paste-p-15131.aspx?gclid=CKyV1KWXmNECFYZMDQodEtUH7A
That product does look to be better than just using short strand fiber glass filler, or the like, that most of us old guys are familiar with. The method you're describing is pretty much what everyone else meant by digging out, grinding out etc. I absolutely agree, the infected material must be removed completely before any repairs can effectively be made.

Who knows, Jim may just find a huge void inside that has got moisture in it over the 45 years ............. well, stranger things have happened!!!

 
I work on corvettes and if someone has used the wrong paint stripper on it the bubbles will keep coming back all the time when it gets in the sun . we have special stripper for fiberglass.

 
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