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Old 06-07-2005, 08:54 PM
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fiberglass prep

can anyone tell me what is the proper way to prep a fiberglass hood before paint, right now its a white gel coat, do I primer, I would like to know the steps involved, do I scuff it up before primer, if so what grit sandpaper, and if I spray primer, should I use a high build, how many coats, and do I sand the primer, if so what grit sandpaper, sorry for so many questions I just wanna get it right.. thanks

chris

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Old 06-07-2005, 09:24 PM
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Prepping a fiberglass hood isn't much deferent than any other body panel....

First check for any deep scratches, nicks or chips. Repair them with glazing putty
block sand it with 220
wax/grease clean it
tack it
apply 1 coat of epoxy followed by at least 2 coats of highbuild primer (this will fill in any other small imperfections)
block sand again with 400/600
apply sealer
and you'r ready for paint.

If it's a new after market hood with a smooth surface and no imperfections (thats rare).....You may just scuff, clean, spray one wet coat of epoxy sealer and your ready for paint.

NOTE It's not absolutely necessary to use epoxy primer with fiberglass, but the extra protection never hurts
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Old 06-07-2005, 10:37 PM
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everything above is correct. just want to stress the cleaning part of it. the part came out of a mold so there is going to be a release agent on it, either polymer, wax or pva so be sure to clean it well or fish eye city. wipe down with wax/grease then acetone. sand it then clean it again. the release needs to be 100% gone.
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Old 06-08-2005, 07:37 AM
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thanks for the reply, thats what I was looking for
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Old 06-08-2005, 07:56 AM
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Clean it first, then I usually block sand as many defects out as possible and fill any voids, just remember that gelcoat needs to be scuffed/sanded before applying any fillers or primers, Block it with 180, scuff up any divits you need to apply filler in then apply your filler and sand. When the hood is looking good, and fits good you're then ready for two coats of epoxy and either polyester or urethane primer surfacers then final sand and paint. Fitting the fiberglass part is a must before moving to the primer and paint steps IMO. The epoxy primer isn't a necessary but it does help to protect the glass from dryout and also acts as a solvent barrier for any of your topcoats and results in better gloss retention/less dieback. These parts usually look good untill you blocksand them and realize how many defects are actually there. Bob
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Old 07-06-2014, 06:03 PM
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I have a fiberglass hood that I need to prep. I've already wash with dish soap and clean with W&G remover. Do all the above recommendations above stilll hold true, particularly do you use 180 or 220 to ready the surface for epoxy? I saw Kevit Tetz's video where he used 220 grit on a DA to ready the fiberglass hood for epoxy. Then I've read a couple threads here that stated to use 80 grit sandpaper. I know that 80 grit is used on bare metal, but is it ok on fiberglass. Needless to say I am bit confused on which paper to start with. I plan to use SPI products and guidecoat, if that helps.

1. Is it best to sand the hood by hand or use a DA to rough up the surface for epoxy?

2. If I need to do repairs on the hood, what body filler should I use? I see Bondo and the local parts store, but read that I should stay away from them. .

Thanks...Al

Last edited by Methodical; 07-06-2014 at 06:27 PM.
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Old 07-06-2014, 06:38 PM
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Quote:
Originally Posted by Methodical View Post
I have a fiberglass hood that I need to prep. I've already wash with dish soap and clean with W&G remover. Do all the above recommendations above stilll hold true, particularly do you use 180 or 220 to ready the surface for epoxy? I saw Kevit Tetz's video where he used 220 grit on a DA to ready the fiberglass hood for epoxy. Then I've read a couple threads here that stated to use 80 grit sandpaper. I know that 80 grit is used on bare metal, but is it ok on fiberglass. Needless to say I am bit confused on which paper to start with. I plan to use SPI products and guidecoat, if that helps.

1. Is it best to sand the hood by hand or use a DA to rough up the surface for epoxy?

2. If I need to do repairs on the hood, what body filler should I use? I see Bondo and the local parts store, but read that I should stay away from them. .

Thanks...Al
Here's photo of the hood
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Old 07-06-2014, 08:22 PM
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something that hasn't been mentioned is UV curing of the fiberglass. If it hasn't been UV cured at the factory, you should UV cure it yourself by letting it sit outside in the sun for 5 days.

You can scuff with 220 by either hand or DA in prep for epoxy, then clean with WGR. Spray 2 coats of epoxy. For filler, it is fine to use a polyester filler such as Rage, or my preference, Marson Platinum. Both are creamy and spread and sand very well, but the Marson Platinum is a little cheaper.

On a hood scoop I did I sprayed it with Evercoat Slick Sand after epoxy, which is spray poly, because of how much correction it needed to get a straight surface. I use SPI as well.

Here's a blog entry I did on a fiberglass scoop.

1967 Mustang Restoration: Slick Sand: Sprayable polyester surfacer/primer
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Old 07-07-2014, 08:49 AM
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something that hasn't been mentioned is UV curing of the fiberglass. If it hasn't been UV cured at the factory, you should UV cure it yourself by letting it sit outside in the sun for 5 days.

You can scuff with 220 by either hand or DA in prep for epoxy, then clean with WGR. Spray 2 coats of epoxy. For filler, it is fine to use a polyester filler such as Rage, or my preference, Marson Platinum. Both are creamy and spread and sand very well, but the Marson Platinum is a little cheaper.

On a hood scoop I did I sprayed it with Evercoat Slick Sand after epoxy, which is spray poly, because of how much correction it needed to get a straight surface. I use SPI as well.

Here's a blog entry I did on a fiberglass scoop.

1967 Mustang Restoration: Slick Sand: Sprayable polyester surfacer/primer
Thanks Lizer. I appreciate the suggestions and link (very informative). Btw, I should've mentioned that I've had the hood for a good while now and it has seen it's fair share of sunlight.

Again thanks...Al

Last edited by Methodical; 07-07-2014 at 08:55 AM.
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Old 07-07-2014, 11:45 AM
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I'm no pro but I just treated the glass in my hood and my fender flares like any metal surface and it worked just fine. Mine was not gelcoated just open fiberglass.

For what it's worth I liked duraglass for filler better than normal feather lite type material but that's just me.

This is the fiberglass hood scoop on an aluminum hood


After epoxy primer


After Paint


After a 3000 miles and lots of stress


It still looks great

Last edited by charchri4; 07-07-2014 at 11:51 AM.
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Old 07-09-2014, 04:13 PM
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I'm no pro but I just treated the glass in my hood and my fender flares like any metal surface and it worked just fine. Mine was not gelcoated just open fiberglass...
What grit sandpaper did you use to prep the fiberglass for epoxy?

Thanks...Al
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Old 07-09-2014, 04:26 PM
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I took the whole car to 220 for the epoxy primer. As I understand it you don't want to go finer than that so you get some physical help in bonding. I shot 5 coats trying to get the filler lines in the 2nd photo to go away. I freaked when they would not cover but the guys here said it was fine and to just block it and paint it. So I took all that primer to 400 wet then shot one more coat of epoxy and 2 coats of paint and they were right. The paint covered like a dream and the thing looks great.
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Old 07-09-2014, 05:10 PM
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[QUOTE=charchri4;2460745]I took the whole car to 220 for the epoxy primer. As I understand it you don't want to go finer than that so you get some physical help in bonding. I shot 5 coats trying to get the filler lines in the 2nd photo to go away. I freaked when they would not cover but the guys here said it was fine and to just block it and paint it. So I took all that primer to 400 wet then shot one more coat of epoxy and 2 coats of paint and they were right. The paint covered like a dream and the thing looks great.[/QUOT

I've seen where folks like yourself stated that they treated fiberglass like metal, so I was wondering if I could use 120 or 180 on the hood to prep for the epoxy since I am block sanding the car with 120 to get it ready for the SPI's black epoxy.

Thanks...Al

Last edited by Methodical; 07-09-2014 at 05:30 PM.
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