How to finish fiberglass

[kmacht]

I need some advice. I am pretty good at working with metal but have never done much fiberglass work. This past summer I decided to do some modifications to the fiberglass cowling on my airplane. This involved bonding the two halves together. I took a course while out at the airshow in Oshkosh and talked to a bunch of people on how to accomplish what I wanted. I successfully did it using a couple layers of BID cloth on either side of the seam. It is now nice and strong but ugly as all hell. I need to know what the right way to finish the fiberglass is. You can clearly see the new layers of glass sitting on top of the old cowling fiberglass. If I were to just sand it a bit and paint it I am sure you would see the weave of the fabric. Do I use something like a bondo (rage, etc) to smooth it all out? Will it even stick to fiberglass? The old stuff outside the area I seamed together is gell coated. Can I just scuff the gell coat and apply some filler or is there something else I should be using. Everything I read about fiberglass has to do with how to mix the epoxy and apply the glass. There is very little on finishing techniques. Any websites, pictures, or tutorials you know of would be helpfull.

Keith

 

[mayday0017]

Something we use to do when making custom stereo's and what not is make what we called "milk shake" and paint it on. We would use 50/50 ratio of bondo to fiberglass resin and use the fiberglass hardner to normal ratio then paint this on over our finished fiberglass work. This provided a very hard finish that was sandable and easy to apply... Might be other suggestions out there but this is what we did for pannels that needed to be painted....

 

[MoonRise]

Yeah, you use the 'appropriate' filler-goop. Apply as needed to smooth-out the cloth weave or other surface imperfections, scuff-sanding previous paint/gel-coat. Then prime and paint.

Leaving out the steps of clean/degrease first, make sure you have 'compatible' resin(s) and filler and paint, don't sand down into the cloth itself just the resin on top of the cloth, and so forth.

http://www.wisegeek.com/how-can-i-finish-fiberglass.htm

http://www.westsystem.com/ss/fiberglassing-a-woodstrip-hull/

http://cvarc.homestead.com/Fiberglass.html

http://airfieldmodels.com/faq/fiberglassing_and_finishing.htm

http://www.bertram31.com/proj/tips/re-gelcoating.htm

http://www.bottompaintstore.com/blog/how-to/how-to-apply-gelcoat/

http://www.fiberglasswarehouse.com/help/epoxybook.pdf

 

[theoldwizard1]

Basically the same as painting a car.

You want to use a "filler primer". Goes on like paint, but is much thicker. You can even get it in a rattle can. Let dry thoroughly, sand it down and you should not see any cloth through it.

If you are a perfectionist, fill and pit (air bubbles) and do another coat of primer.

The best paint for airplane is Imron or any catalyzed polyurethane. Make certain to follow label instructions about prep or it will just peel off. This paint is tricky so you might want to hire a pro.

 

[Guster]

Resin + filler or body filler to fair and sand. Gelcoat, prime and paint or upholster to finish. Otherwise if you want the out of the mold look you have to make it in a mold and clearcoat as desired.