Do you treat fiberglass different?

[Shade]

I'm working on the fenders on my 84 stepside but am unsure what to do after 'glass repair. Is there anything different I should do to the glass that you don't need to do to steel? I'm also unsure about sealers; what sealer should I use and what stage do I use it at? Do I seal right on top of bare steel/glass or seal after primer just before paint? Thanks for any help guys.

[Sand_Man]

I don't know if you have already done the 'glass work or not, but if not, here's my method. First, all fibergalss repairs need to be done from the front (finished) side. If done form the back, the repair will show, even though paint. Get the fiberglass mat and resin close, then use a fibergalss-reinforced filler to get level. Once you have it level , spread a thin coat of regular filler, and block sand. This fills most pinholes and helps hide the 'glass strands. Once this has been sanded (I start with 80 and finish with 220 grit) then lay down three wet coats of epoxy primer on the repaired area, let it flash between coats, and then shoot two more wet coats over the whole part. Let that cure, then shoot a guidecoat over the whole part and block it with 320 grit wet. You may need to use either some glaze or filler, but no matter what you use, make sure it's catalyzed. Never use any of the non-hardened stuff for anything. Once you think it's good, prime, block and paint like you normally would steel. I do the fiberglass repair on my brother's racecar as well as show car fiberglass, and I think the trick is to use the best materials you can buy, let the primer cure completely and use a good catalyzed sealer before the color goes on.

[Sand_Man]

I just re-read you post and forgot to add anything about sealers. I use House of Kolor, so this applies to their product, other stuff may have other recommendations, follow the maufacturers suggestions as if they were chiseled in granite. Having said that, here's what I do: once you have the surface primed, I wet sand with 400-grit. Once that's done, wipe the whole car down with a brand-new sponge and clean water. Don't wash the car, just damp the sponge and wipe all the sanding residue off. Next mask off the car or part with new paper and tape. Don't use newspaper, it's dirty and cheap. Real masking paper is less than $6 for a good sized roll, so use it instead. Once it's masked, I wipe the whole thing down with a clean rag damp with a water-based post-sanding prep. I don't like solvent based wipes, and if you wash your wiping rags, never use any of those drier sheets like Bounce. Once it's wiped down and dry (and warm!) mix up the sealer and shoot two medium coats. Sealer is not intended to be sanded, but if you get a bit of dirt or a run, then make very sure you fix it first, but otherwise try to lay it on as smoothly as you can. Once the sealer is on, you have a limited time to apply color, with House of Kolor, they recommend no longer than 1-3 hrs depending on who's answering the tech line (j/k) I let it sit long enough to take a slow walk around the car and check for boo-boos ( 20 minutes or so) the mix color and paint. No need to wipe it down unless you had to do a quikie sand job in a spot, then lightly wipe it with your cleaner. You'll likely find that every painter does things differently, some use anti-static wpies on 'glass, some use Windex, some feel that wiping at all causes static buildup on fiberglass. I treat it like steel and have yet to have any problems, for what that's worth. Hope this helps, Jim

[e-tek]

Make sure you've sanded it all with appropriate grits (40-120 for filler, 120-240 for glaze, 240-320 for primer). Once the repair is done, you'll use a lightweight body filler to straighten/shape, then glaze to smooth. Then spray high build - no need to etch.

Sealers go on last, just before paint. They seal off everything (both ways) and provide a uniform substrate for paint.

[gt350h]

The only thing I would say is don't try to block epoxy primer. I think maybe sand man might of meant high build in there. I'm not sure.

[Sand_Man]

HoK's epoxy is also a high-build, plus it sands very easily, so that's how I do it. On my brother's racer, I don't block it much at all, since it is race car fiberglass and blocking would be a waste of time, so I just use PPG stuff since it's quicker and cheaper.

[gt350h]

Sorry, forgot there's a few brands out there of epoxy surfacer.

[e-tek]

I've been switching over to the etch/highbuild product - much easier to deal with.

SEM ML010 - METALOCK DTM GRAY EPOXY HIGH BUILD PRIMER KIT (PRIMER GAL. + ACTIVATOR QT.)*

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Description
ML010 METALOCK DTM HIGH BUILD PRIMER KIT is a true direct-to-metal epoxy primer designed for
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[gt350h]

I tried some of the SEM Metalock. I didn't really have good luck with it. It was hard to sand and clogged the paper really bad. It dried with plenty of time and I even tried baking it another time I used it. Maybe E-tek has had better luck. Definitely wet sanded better, but was really gummy. DTM epoxys have been made by a bunch of brands a bunch of times, but I don't think any of them are outstanding. But they definitely cover a few processes in one shot. E-tek, have you ever tried PPG's NCP-271? I think its the best of everything.....except price. Its not cheap, but it has incredible fill, great corrosion resistance and it sands dry or wet flawlessly. But I know price can play a big role in primer choice.