bumps in glass, and bondo
Printed From: the12volt.com
Forum Name: Fiberglass, Fabrication, and Interiors
Forum Discription: Fiberglass Kick Panels, Subwoofer Enclosures, Plexiglas, Fabrics, Materials, Finishes, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=31425
Printed Date: July 24, 2025 at 11:07 PM
Topic: bumps in glass, and bondo
Posted By: nyguy4u
Subject: bumps in glass, and bondo
Date Posted: May 01, 2004 at 11:53 PM
Ok, so my box is complete. 3 layers on the outside, 5 on the inside. Bear in mind, this was my first glassing project, so obviously I couldnt keep it perfect. With that said, there are hard bumps everywhere! Some are air pockets, some are just glass that balled up. I tried a palm sander with 60 grit, and it does nothing!. Do I need a belt sander with 40 grit to get this smooth?. After it's smooth, I realize I need to bondo. Here is where I am stupid. I've never used bondo before. How do I apply it to the box?. I assume i'm not using a brush. I know after its applied to sand bondo sand bondo countless times, but after the bondo is done.. do I need to prime it?. I am going to use bed liner as my finish, so is primer needed?
Replies:
Posted By: auex
Date Posted: May 02, 2004 at 1:21 AM
For the bumps keep sanding and sanding. As for the bondo, first you mix it with the cream hardener and apply it with a spreader, this looks like a big putty knife without a handle and is made of a rubberized plastic.
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Posted By: bp_viper
Date Posted: May 02, 2004 at 8:25 PM
if you are using bed liner as a finish you shouldnt need to prime it. primer is mainly so paint will stick to it. the directions on bondo is usually pretty good. make sure you mix in the right proportions or it will either never harden or take forever. good luck
Posted By: TAudio
Date Posted: May 03, 2004 at 10:55 AM
to sand down the glass i just use a sanding wheel on a drill. Quick and easy.
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Posted By: sam1
Date Posted: May 03, 2004 at 11:22 AM
you can use a dremel to get the bumps off and i also cut out the bubbles with it too, because the bubbles are going to be weak spots in the fg. but with 8 layers, you should be fine as long as theyre not huge and everywhere. but yea, dremels work wonders. i bought a cordless one at target for 20 bones and a complete set of cutting and sanding attachments for another 10 or so. also, if youre going to paint, i would always suggest priming it. and youre going to have to sand the sh*t out of it to get a nice and smooth finish. a guy on another forum said that if you mix bondo and fg resin 1/2 and 1/2, then add hardener, that it works even better than bondo. it goes on smoother and is easier to sand, saving you lots of time. i havent tried it yet, but you might keep that in mind.
Posted By: pureRF
Date Posted: May 03, 2004 at 4:39 PM
I had the problem with the little balled up chunks of resin and to get those off you can just take a flathead and hammer, put the flathead up to it then hit it from behind witht he hammer. It should pop right off. Then sand. That should help a lot with trying to sand it and it tearing your sandpaper to hell.
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