Hood from Hell, need advice

R

Revolver

72 Olds 442, factory fiberglass (actually, I think it's SMC). Based with Pro-Spray dark metallic green with some gold pearl. Base sat overnight, then 2 good coats of UV clear. Sat for a month. Wet sanded with 400 and gold pearl stripes applied. Sat overnight, then cleared with 4 coats of UV clear. Unfortunately, found some spots in the green that I didn't like. Namely, fly shit that I missed before clearing. I would have left it, but the owner is picky. Wait a week, sand with 400 (again), spot in the green. Here's where I went wrong. Did the spot repair with my touch-up gun (and not my regular gun), trying to keep the repair small. As soon as I put my first coat of clear on, it was obvious, the repair is visible. Went ahead and put 2 coats of UV clear on.

That was sunday. How should I proceed with the repair? I've got time to let it sit. The hood is in the back of my shop, temp is between 70-80*. Getting the hood into sun would be a pain, but I can do it if it's best. Should I sand it with 400 and let it sit awhile, then respray the green and clear? Want to avoid problems with the hood in the future (shrinking, cracking, dieback, etc.)
 
Shame too, the hood came out really god with the 4 coats on it



One bright side, I'm getting really good at spraying the UV clear
 
I'd sand it and mask off the stripes so you can carry the green blend out farther using the same gun you sprayed it with originally. Then you can peel the masking off the stripes and clear it once more.

The only wild card is you have a tremendous amount of material on there. Since you said you have time, sand it and put it in the sun for a spell before proceeding.
 
crashtech;n75685 said:
The only wild card is you have a tremendous amount of material on there. Since you said you have time, sand it and put it in the sun for a spell before proceeding.
Click to expand...

Thanks, Crash. That was my worry also, the amount of material on it now.
 
If hood was stripped at this point would not worry about the mils BECAUSE the mils will be the clear with a small spot of base, so will expand and contract at same rate.
I have probably over the years had more mils of clear alone on vettes then you have with primer, base and clear.
 
So Barry, would I be good with sanding with 400, masking off the gold, spraying the green base and then laying on 4 more coats of clear? This weekend? I can get it sanded and out in the sun tomorrow, then base on Saturday and clear on sunday.
 
Well, it just keeps getting better. Got out to the shop late this morning, so I decided to set the hood in the sun (without sanding) while I worked on other things. Was out for probably 3 hours, no clouds, 80*, pure sunshine. Just looked at it and I've got 3 blisters!!! All 3 are in the same general area (end of the stripe on the driver's side, near windshield). Obviously, I have some moisture in there, somehow. Hood is back inside. How would I go about fixing this? Start sanding carefully to find out where it started from? Really need some help on this one.
 
At least you found it now instead of the owner finding it. Cut them open and smell them, if you smell solvent, there was solvent trapping and that comes from a lot of things but mainly too much material too fast. Other than that it could be contamination on the bare metal.
 
Just cut them open, and yes I believe it's trapped solvent. Looked over the whole hood and found some more, smaller blisters. So, what is my next step? More time in the sun? Surface temp was 126* when I pulled it back into the shop.

I'm now kinda worried about the rest of the job. However, the main body and doors have been painted for about a year, the fenders are about 6 months old. Last things were the hood and trunklid. Trunk was good after the 4 coats of UV and has been sanded with 1000 already. Think i'll set it in the sun tomorrow, too, and see if anything happens.
 
Sorry about that. Is there anything about your process that you think might have been a problem? Do you remember clearly everything you did? Do the blisters go down to metal, or to primer?
 
Crash, the hood and trunklid are the last pieces I've been working on. Hood was stripped to the bare SMC and epoxy primed. Did some filler work with the Vette adhesive bondo that Shine recommends, then primed with Turbo. Then it sat for many months. Sanded the Turbo and reprimed with SPI 2K. Sat for a week or more. Scuffed with a red scotchbrite and sealed with reduced epoxy. Sat overnight, then started base. Might have rushed the base, even though I give about 15-30 minutes between coats.

When I cut the blisters last night, green base color came up with them, but some green was left under the cut. Not full green, but black (color of the sealer) with some green in it. Trunklid was done at the same time (2K, sealer, base, and clear) and it's sitting in the sun right now with no blisters. Hood was closer to my fan (kinda in a corner) when they both were sprayed.

Put the hood back in the sun today and another large blister is starting to show. I'll cut it later and put it back out tomorrow.

Thank you for your help, I'm really at a loss.
 
So it seems like the problem is in the basecoat, then? Can you detail the brand of base, brand and speed of reducer, temp when spraying, etc? Maybe a new procedure can be found that will minimize your risks.
 
Pro-Spray base, slow SPI reducer, probably mid 70*- low 80* spray temp. Base mixed 1:1 with reducer. Trunklid sat in the sun today, probably 3 hours, no problems. Hood and trunklid were sprayed at the same time, same procedure. Only difference is the hood had some spots re-based and 2 more coats of clear added. Trunklid was covered with plastic while this happened. (not covered in the sun, but covered when the hood got 2 more coats of clear)

Everything metal is coming out fine. Even took a fender off the car and set it in the sun for a bit, no problems. Only the fiberglass (SMC) hood is giving me trouble. I'll cut the big blister out later tonight and let it breathe. What should I do with the smaller blisters? Really too small to cut out with a razor. Think i'll put it in the sun again tomorrow and worry about fixing it next week.

Thanks again.
 
I was hoping some others would post so we could build a consensus. For now, feathering out the blistered areas and letting it sit in the sun is probably the best choice. Then you can start priming the feathered areas back up a couple coats at a time. That's what I would do, anyway. But I'm still not sure what caused it, because your procedures don't have obvious flaws. Maybe activate the base this time and let it sit overnight before clear? That's usually a bulletproof way to do it.
 
I hate to be the one to say it but stripping it and starting over would be your best bet. Leaving it in the sun a few hours is not the same as giving it to the owner and driving it all day and showing it all day in the sun. If they appeared in a few hours in the sun now, later they could keep appearing and that would make you look bad and you don't want that.
If I had to guess as to what could have happened you may have put your base on too soon after wiping it down traping degreaser solvents.
Sorry to bring bad news but that is what I would recommend be done.
 
Seeing that DATEC said it first I gotta agree. Strip it, then let the fiberglass/smc air out for a couple of days to get any remaining solvent that's trapped in it out. More than likely this happened when you laid down your first coats of epoxy (I'm assuming that's what you used). Too heavy, not enough flash time, and it soaks into the 43 year old fiberglass. You did use only epoxy or poly on the bare fiberglass correct? If not and you put urethane (turbo) on the bare fiberglass (even small sand throughs) that would definitely cause the issues you are having.

If it was mine and I was redoing it I would skip the epoxy and go with some polyester primer. Medium wet coats with plenty of flash time. Poly bonds well with fiberglass and seems less "reactive" which helps when you are having issues like you are having. Probably not what you want to hear but if you don't you'll just keep chasing your tail and end up spending more time than what it would take to redo it once.
 
It's hard to disagree with starting over, though opinions will vary on the appropriateness of the various primers, epoxy, poly, and urethane. Any or all of them could be used effectively on fiberglass/SMC with the right procedures, imo.
 
I worked on one these 442 hoods a few years back and it was a nightmare also ! Upon getting it stripped it basically had little to no gel coat left on. It had a rough pop mark surface like the moon. I called talked to Barry and basically started by first getting some epoxy saturated into the hood and texture and pinholes. I then ended up skim coating entire hood with z-grip. I then sprayed it with slicksand and prep it and sprayed it with black epoxy and went to paint/clear.That hood was black/white stripes. It has tighten up a bit but has held up pretty good but after 5 years really could use a light 2000-2500 to get it perfect! Good luck. keep us updated on your progress.
 
I have four 56 Ford F series truck hoods to do and Im really dreading it. three of the four need various stages of straightening and when its done, you still have a 56 Ford F Series Hood. One of the nicest looking trucks ever produced, but the worst hood hinge design I have ever seen.
 
You must log in or register to reply here.
Back
Top