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Everyone’s heard of Bondo, but were you aware that they make a range of other materials, many of which are useful for purposes other than lowering the resale value of your car?

We ran into one of those, um, other uses this week when we were modifying some interior console panels in a GMC Denali pickup.  While we were able to create some of the surfaces with wood, we used Bondo’s Bondo-Glass fiber-reinforced filler material to create some of the more complex curves.

Bondo-Glass works a lot like traditional Bondo in that it’s a two-part substance: the core material and a “hardener” agent that activates it.  Once mixed, the material is workable for about five minutes, quickly solidifying into a hard shape that’s sandable and paintable.  The major difference from the classic filler, of course, is the inclusion of fiberglass filler material which drastically increases its strength.

In our experience, the surface created by Bondo-Glass is far from finished and required a bit of Bondo surface glaze to smooth it out.  This is largely caused by the difficulty in applying the ‘Glass smoothly without creating significant bubbles and cavities.

However, we were blown away with the strength of the hardened ‘Glass.  We were able to use significant amounts of it without fear of cracking or splitting — a prime concern with the original filler.  For our project, it worked perfectly.

You can find Bondo-Glass in most auto-parts stores in pint containers priced around $13-$15 per pint.  We recommend picking up some extra Bondo Cream Hardener which sells for around $2.50 a tube as we discovered that it was handy to adjust the material’s work time by adding a bit of hardener sometimes.

Bondo-Glass Reinforced Filler, Pint [Bondo]
Street Pricing [Froogle]


9 Responses to Finds: Bondo-Glass Reinforced Filler

  1. Paul says:

    This is butcher crap one step up from stuffing holes with steel wool. Just say no! If your job needs this stuff your job needs a rethink. I mean who the hell wants little glass fibers sticking up out of their finish anyways?

  2. Chuck Cage says:

    Paul: Don’t be a material snob. This has lots of applications. If you read the post, you’d see that we’re not using it for car body work — or even for the final finish. Just because lots of people misuse Bondo products while performing amateurish auto body work, that doesn’t mean the material isn’t quite useful elswehere.

  3. Paul says:

    Hey Chuck just stick with fiberglass resin when you want glass. That stuff is magical! Then Bondo over that if you have to. Heck I even have Bondo thinner. You know that purple stuff that oozes up in the can? You can buy it. Makes your Bondo even silkier.

    And there is nothing amateurish about using plastic filler correctly with bodywork. All cars come from the factory with some plastic filler on them. The days of leading seams are long gone now. I’ve used a lot of Bondo, and a lot of fiberglass over the years. They work just fine each doing its job.

    I’ve said it before, and I’ll say it again, this inbetween product is just for real butchers. I see no place for it except to fudge jobs. But maybe Chuck has found a legitimate use for the stuff? Chuck’s application does sound rather unique. I can’t say as I’ve made interior console panels out of Bondo. Hey, as long as you’re happy. Sure sounds like a hack and slasher to me though 🙂

  4. Chuck Cage says:

    Paul: Fair ’nuff. Hey — a quick question: We were using the Bondo Glass to fill spaces that were too big for standard Bondo but still pretty small. On the other hand, we’re getting ready to create a few full panels that we’d like to make entirely out of fiberglass. Can you recommend some good sources for glass mat, resin, and other basic fiberglass supplies?

  5. Paul says:

    I’ve been buying my glass at the Home Depot lately. I’ve often wondered if the fiberglass rolls used for glass and emulsion roofing would work though. I never bought the stuff, but I’ve sure rolled out a few of those rolls. Could check with a roofing supply house on that.

    This place seems to have a better deal than the Home Depot does in quantities of fiberglass:


    By the looks of it mat should be way cheaper than weave.

    And never underestimate the power of Wallyworld (Walmart), usually if they stock it, they have it at the best price possible. I haven’t checked their fiberglass prices, but I bet if I did I’d want to kick myself.

  6. nrChris says:

    I am with Paul on this one–machine to fit. I helped a buddy replace gauges in his 300Z. It was an 80’s model with a complete electronic dash. When the dash went on the fritz he decided to use NOS gauges from a few years earlier. The biggest PIA was fitting up a sheet metal template to hold the gauges in place. But once that was done you could really not tell that the car did not come this way from the factory.

    (The first inclination was to rough cut the sheet for support and fill the bejeezus out of everything after the fact.)

  7. TimG says:

    The best bodywork in the world still uses ‘some’ body-filler. You just can’t get the surface smooth enough with metal work (ok, ok.. you probably could..but would you want a great paint job to cost $20k.. thats how much time it would take). As folks have stated above, proper use can last the lifetime of the vehicle.

    Just because some dummie used a glob of Bondo over rust doesn’t mean Bondo sucks!

  8. Fong says:

    Custom Car Audio guys will tell you this stuff is great for support geometry. Sometimes you can’t get just the right shape with wood alone so the bondo helps smooth out all the transitions before laying down the glass.

  9. Cal says:

    I bought bondo gold but the hardener was stolen from it when I opened it, but I have hardener left from the original bondo body filler(not the gold) could I use the original Hardener with the gold filler achieving the same finished product? Aka are the bondo hardeners universal?

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