I am attempting my first fiberglass project on a ply and balsa hydroplane. I have the first layer done with 2.3 oz cloth and it came out pretty good. I have a couple spots where it bubbled, (maybe an inch or two by a ¼ inch), but nothing that can’t be fixed.
My question is on sanding. I used polyester resin without wax. I am planning on a couple more coats. In the resin, you can see the brush strokes from the 2” brush I used. (Just a cheap brush) I am using 100 grit sandpaper with a 2 hand electric Black and Decker sander, and I can barely scratch the resin. Then I tried a 4.5” angle grinder with an 80 grit pad, and wound up making larger gouge marks then the brush strokes.
2 Questions.
1. How do I sand the brush strokes out in between coats ?
2. Should the small areas that bubbled be filled in with resin, or can they be fixed with puddy and sanded smooth
What exactly is the best way to get fiberglass to have a glass smooth finish ?
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Some fear the Abyss... Other, chase it into the DEPTHS !!!
add your fiberglass layers untill you get the thickness desired. apply a coat of body filler over the project and sand that smooth. it will fill in all the brush strokes. and BTW, you uploaded your pictures wrong.
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Dustin Rockney
Rockstar Autosports
After the last layer of matting dries, take some 60 grit and do a once over everything to even out little peaks or loose pieces. Then use the body filler to patch holes or grade slopes and what not. Apply it with the largest rubber spatula you can use for the area. To prevent humps. The fiberglass will always have little air pockets here and there. So almost all sanding should be on the filler. From there its just moving through the sand paper ladder. Eventually it can be as smooth as good paint can be.
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