Help with Fiberglass Hood Prep Please
04-08-2007, 10:47 AM
#1
Help with Fiberglass Hood Prep Please I've searched the board but could still use a little advise. The hood is fiberglass and was made by VFN. Eventually I will have a professional paint it but I wanted to do some of the prep work myself. I don't want to screw it up so I figured I'd check with you guys first.
The hood arrived with a black semi-gloss coating. It looks like there are lots of little ripples and imperfections. I plan to block it by hand and use polyester high build primer and just keep spraying and sanding until it's smooth.
I don't know if it makes a difference in prep, but the hood will either end up with a metalic pewter/clear finish coat, or maybe black/clear, I'm still not sure.
Any prep tips would be greatly appreciated! Thanks!
The hood arrived with a black semi-gloss coating. It looks like there are lots of little ripples and imperfections. I plan to block it by hand and use polyester high build primer and just keep spraying and sanding until it's smooth.
I don't know if it makes a difference in prep, but the hood will either end up with a metalic pewter/clear finish coat, or maybe black/clear, I'm still not sure.
Any prep tips would be greatly appreciated! Thanks!
04-08-2007, 07:36 PM
#2
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The advise I am going to give is with the assumption that you all ready know how to use a sanding block, filler and a paint gun.
I would advise first washing the surface with soapy water. After it dries, wipe the surface again with a wax and grease remover, something like PPG 330 or 440.
That should eliminate pushing any surface impurities into the sanded surface.
I am assuming the black coating must be the gel-coat. You do NOT want to sand through that coating. It is there to seal the fiberglass material, which can be porous. Get yourself a decent flat sanding block and scuff the surface with something like 120 or 150 grade dry paper. Don't try to take off a lot of material, just kill the shine and provide a bite for the primer. Take note of any glossy (low) spots AND PINHOLES that are left behind.
After that, use your air hose and blow off all sanding residue. Wipe the surface again with the 330/440 and you may see more pin holes. After it is dry, apply a thin coat of a good polyester glaze filler to the pin hole areas, using slight pressure to be sure the holes get filled. (I happen to prefer Dolphin Glaze, made by Upol. 3M makes some, too.) Also scuff and fill the low areas. When the filler has dried, you can block sand or DA the filler down. Take off enough filler over the pin holes so that you can practically see a dot where it used to be. Otherwise you will end up with lumps on the surface. Use your sense of feel to judge how far to sand the low spots.
When all of that is done, you can apply your primer. Put at least two/three good wet coats down. Allow it to dry a few days if you can, so that it can shrink down.
Next, lightly fog a contrasting color (spray bomb) over the surface. Flat black works well. This is a blocking guide coat. From this point you have to start block sanding and re-priming, using progressively finer sand paper each time. Whenever your blocking leaves the guide coat untouched, you have a low spot. Also look closely for any more pin holes. Any defects can be wiped over using the polyester glaze I described, just be sure it is sanded. You can also expect to show gel coat through some areas as you block. The object is to level the added primer and the gel coat to the same plane. You may even have to re-prime and block a couple of more times before you are at the paint prep stage. I suggest getting down to a 320 or 400 grit before the last coat of primer.
After your last primer coat (and guide coat), give it a couple of days again and then begin your final sanding. If you are going with a non-metallic, you can probably use 500 grit. If you are using a metallic base, 500 might leave scratches that would disturb the metallic flakes, so I would go with a 600 or 800 grit.
I hope that helps. And I am speaking from my own (32 yrs.) experience, not what I read somewhere.
I would advise first washing the surface with soapy water. After it dries, wipe the surface again with a wax and grease remover, something like PPG 330 or 440.
That should eliminate pushing any surface impurities into the sanded surface.
I am assuming the black coating must be the gel-coat. You do NOT want to sand through that coating. It is there to seal the fiberglass material, which can be porous. Get yourself a decent flat sanding block and scuff the surface with something like 120 or 150 grade dry paper. Don't try to take off a lot of material, just kill the shine and provide a bite for the primer. Take note of any glossy (low) spots AND PINHOLES that are left behind.
After that, use your air hose and blow off all sanding residue. Wipe the surface again with the 330/440 and you may see more pin holes. After it is dry, apply a thin coat of a good polyester glaze filler to the pin hole areas, using slight pressure to be sure the holes get filled. (I happen to prefer Dolphin Glaze, made by Upol. 3M makes some, too.) Also scuff and fill the low areas. When the filler has dried, you can block sand or DA the filler down. Take off enough filler over the pin holes so that you can practically see a dot where it used to be. Otherwise you will end up with lumps on the surface. Use your sense of feel to judge how far to sand the low spots.
When all of that is done, you can apply your primer. Put at least two/three good wet coats down. Allow it to dry a few days if you can, so that it can shrink down.
Next, lightly fog a contrasting color (spray bomb) over the surface. Flat black works well. This is a blocking guide coat. From this point you have to start block sanding and re-priming, using progressively finer sand paper each time. Whenever your blocking leaves the guide coat untouched, you have a low spot. Also look closely for any more pin holes. Any defects can be wiped over using the polyester glaze I described, just be sure it is sanded. You can also expect to show gel coat through some areas as you block. The object is to level the added primer and the gel coat to the same plane. You may even have to re-prime and block a couple of more times before you are at the paint prep stage. I suggest getting down to a 320 or 400 grit before the last coat of primer.
After your last primer coat (and guide coat), give it a couple of days again and then begin your final sanding. If you are going with a non-metallic, you can probably use 500 grit. If you are using a metallic base, 500 might leave scratches that would disturb the metallic flakes, so I would go with a 600 or 800 grit.
I hope that helps. And I am speaking from my own (32 yrs.) experience, not what I read somewhere.
08-13-2011, 11:01 AM
#3
damn!....and i was about to ask after doing a search..... what can i do to prep my VFN hood to try and cut down on the cost of prep/paint.
Im not a paint guy so i dont think i'll tackle this job, i didnt know it was that much work. I lightly wet sanded it with 600 and 1500 just to make it look half way decent cause i think its going to be awhile before i can get it painted. "like a long time"
my paint guy quoted me $600 for prep/paint both sides of my hood along with blending the fenders.
Im not a paint guy so i dont think i'll tackle this job, i didnt know it was that much work. I lightly wet sanded it with 600 and 1500 just to make it look half way decent cause i think its going to be awhile before i can get it painted. "like a long time"
my paint guy quoted me $600 for prep/paint both sides of my hood along with blending the fenders.
