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Old 03-02-2004, 05:26 AM
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4x4n In A Cherokee In Colorado 4x4n In A Cherokee In Colorado is offline
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Join Date: Oct 29, 2003
Location: Canon City, Colorado
Posts: 757
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Ok lets do some fiberglass prepping!! This is for Mudder Trucker, who ask for it!

Fiberglass use to be pretty sub par, but in the last 10 or so years, fiberglass has come miles higher in quality..

Lets say we get one of those fiberglass hoods with a scoop, for our FSJ..

When you get the piece, inspect it well. It may have some low/high spots, also may have some rough edges...MAKE SURE you do a trial fit..Now would be the time to fix it, not after its painted!

Most production glass will come with a generous coat of gelcoat, its pretty shinny, so it shows highs and lows pretty easy...

I like to get some good carwash soap and soak the panel down well, youll see highs/lows better this way. By washing it, it will get any grease or mold release off. Rinse with HOT water if you can..Blow or let it air dry..

Heres an important WARNING! Fiberglass has a funny abillity to hold a huge amount of static electricity...As your prepping it you are charging the glass. It will shock the heck out of ya!!..Many times you will feel the hairs on your arm being pulled by the static when working on it...I have seen, plus myself have had some interesting times with glass...I like to use wax and grease remover as a final stage before paint...This stuff is very flammable..I for one, and have also seen it to, have applied the grease/wax remover, then caused a spark and lit the whole panel on fire...I've done this once, seen it twice, so its not that uncommon...

There is a nifty trick that will totally solve this problem...I use PPG DX103 plastic cleaner, its made of alcohol mostly...

Heres what you need to do::Get some denatured or any kind of alcohol works(tried em all). Pour some in a spray gun...Then just mist coat the glass panel with it, you dont need to soak it, just mist it....It will remove ALL static cling instantly!!! It works GREAT!! Please do this before using any kind of flammable material on glass(that includes paint).

If you see any highs, mark them, get a orbital long board, mudd hog, hand board, or inline long board with 80 grit on it...You can remove any small high spot this way. Most highs in production glass are small and can be removed generally, without going thru the gelcoat..

If you have a low spot. Hit that spot with some 80 grit on a DA just to roughen the low, go beyond the low by like 6 inches, so your putty can feather into it. Dont break thru the gelcoat if possible..

I like to use the two part putties, like Half Time by USC, or poly glaze by Evercoat..These work great on gelcoat. Only apply the putty up to 1/8th inch thick, any thicker use bondo...

Smooth/blend/level your areas with 80 grit...

If you see any chips or rough edges, you can also use the putty to fill any imperfections..

Go ahead and DA the rest in anything from 80 grit to 180 grit depending on how much primer you think youll need...If its a fairly rough piece, that may need some minor blocking, prep it with 80 grit, then apply 3-4 coats of primer..If its a fairly nice piece, that may only need a few coats of primer, do your prep work with 180...

You wont need an etch at all. That would include epoxy...Most primers are spec'd to be able to use on fiberglass...Check the howto sheet or check with your paint store to make sure the primer your using will work on glass..

You may do the similiar priming stages as we done on the hood in previous posts. Prime the body work first and fill any minor lows with primer...You may want to spray the whole piece then check for any lows also...That would probably be your best bet...Spary the entire panel...Check for lows, spray the low spot/s with a couple more coats, then finish priming the panel...

There is some glass out there that is so nice, that it wont need any body work...If thats what you have, then guide coat it, and DA it with 240 if you will be using sealer...If not using sealer, which I wouldnt suggest, prep it with 320...Then after dry sanding, use 360/400 wetsanding with a soft block like we used before on the steel hood...Do high crowns, or edges by hand, without a block...You can also use the two part putty to fill any pinholes any minor imperfections when doing the prep work..Just go ahead and finish those areas in the same manner as previous, 240-320 dry, 360-400 wet...

You could just wetsand it with 360 also, not doing any dry sanding...Any of these can work...

After priming, let it dry, flip the panel over and get it coated with something. I like rubberized undercoat, it makes the glass underneath look a little better, but it wont be shinny...If you'd like it shiny, then get some red scotch brite, and scuff the underneath decently, doesnt have to be perfectly sanded, paint will stick well..I like to use epoxy as a sealer, then paint over that...

Mask any painted or coated areas before painting the topside...

Youll see that gelcoat is a pretty hard substance and will require some work to sand it..

I have only discussed fiberglass prepping here, not fiberglass repair...

Any further questions, please post them...

Till Later, Carey
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80 Cherokee S W/T 360/727/208 Daily Driver to Work Everyday driver. Really nice original Interior. My own Cool black paint job, with an AMC theme. Custom manual rear window. Painted Razor grille. 4 inch BJ's lift with Rancho shocks, custom fabbed bumpers, steel Levi rally wheels with 32 BFG at's. TFI upgrade, '98 S10 Blazer power steering box.
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