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Homemade Bondo? Answered

Is there a way to make something like Bondo from common houshold products?




Best Answer 1 year ago

I realize this question is 7 years old but just wanted to add this for those who might see it in the future. I've had respectable results making my own "glazing putty" using talc as the thickener. Purists might scoff at this idea, but it does seem to work and I've used it under some "show quality" paint jobs. I use this as as step between the base coat of bondo and the next coat of sandable fill primer. I find that fill primer is too thin to fill all the imperfections and bondo is too thick and difficult to sand to use as a finish coat. I mix the talc with acrylic primer if I'm going to be spraying acrylic on top or with enamel primer if I'm going to be spraying enamel. Have not tried it with lacquer...but then not many folks spray lacquer any more. Basic rule of thumb, mix the talk with whatever type of paint you will be spraying over the top of it. I generally mix in a ration of 3 parts talc to 4 parts paint primer. But the more talc, the thicker of filler. 3:4 makes a thick soup which will actually self level to some extent yet it is thick enough to fill pin holes, scratches, indentations and minor surface irregularities. I apply the paint with a brush using the "tipping" method. I've also had some luck applying with a brush and then swiping the surface with the edge of a plastic credit card (or similar material). If mixing the talc with enamel, be sure to allow sufficient time to dry before attempting to sand. Minimum of 24 hours and 48 is even better. Otherwise you'll make a mess of things and clog up your sandpaper quite quickly. Two part (mixed with hardener) acrylics will dry much faster and you may even need to use a retarder to prevent it from setting up too quickly. Might take some trial and error to get just the right consistency that will work for you.

Not really... at least, not nearly as cheap as the real thing.

Bondo is a polyester resin with filler. Something similar could be made by adding filler to epoxy glue, but when the filler and epoxy cost are factored in, you can't get near the (approx) $15/gal cost of bondo (cheap epoxy is about $50 a gallon). Plus, getting the right texture is a lot of trial and error. I've made epoxy+filler and it's always either too stiff or too runny.

If all that's needed is a little bit of filler that will go in a fairly thin layer, "glazing putty" sold by the tube at auto stores is fairly cheap. But it *dries* (solvent evaporates) and isn't suitable for sections much over 1/8" thick.