Bondo

[Tom Bender]

Auto Body Filler has it's uses in my shop. When a mortise is good on the surface but oversized in the center, this stuff is easily formed to provide a more sturdy fit, unlike most epoxy which tends to run out. Also, it sands easily and it's inexpensive.

It can also be used to fill voids under paint and probably under veneer though I've never tried it.

Anyone else use it?

[Matt Day]

Could you clarify how you use it in M&T joinery? How well does it take glue? Never heard of it being used like that, and would be concerned about it with glue.

[Steve Fish]

One of my favorite uses for bondo is repairing holes and chips in MDF

[Frederick Skelly]

Auto Body Filler has it's uses in my shop. When a mortise is good on the surface but oversized in the center, this stuff is easily formed to provide a more sturdy fit, unlike most epoxy which tends to run out. Also, it sands easily and it's inexpensive.

Tom, I'm sorta tagging on to Matt's question. I'd be concerned about creating a weaker joint than if you filled the gap/void with veneer? I say that because bondo is pretty much just talc in a binder. It sands easily because it isnt very hard or strong.

Fred

[Tom M King]

A guy told me once that he bought some to work on his car with. He got a gallon can. It was a nice warm day. He mixed the whole batch up, and then went in the house to eat lunch before he started to work on the car.

[Jacob Reverb]

A guy told me once that he bought some to work on his car with. He got a gallon can. It was a nice warm day. He mixed the whole batch up, and then went in the house to eat lunch before he started to work on the car.

Did it burn the house down? :p

[Matt Day]

A guy told me once that he bought some to work on his car with. He got a gallon can. It was a nice warm day. He mixed the whole batch up, and then went in the house to eat lunch before he started to work on the car.

That guy wasn’t very smart.

[Stan Calow]

I used it in place of timbermate or DAP wood filler to fill areas of wood rot on the trim of my house (hardware store ran out of the others). Its held up OK for three years or so. I give it a poke every now and then and it's stayed solid.

[Rob Charles]

While I understand your approach & its' ease... personally, I am more of a VE or epoxy resin w/ microspheres or other thixotropic additive. Habits from the boat repair days.

[Mark Gibney]

Bondo is great when filling dents in items you want to paint that day.
But I use SculpWood putty for large voids and SculpWood paste for checks and cracks in charactery wood when it’s going to be clear-coated. It sets up overnight.

It’s a two part epoxy and has a much longer open time than Bondo, 20 - 30 minutes. It also sands well and doesn’t stink. The color can be modified with powdered colors.

[Rick Potter]

I once (20 years ago) rebuilt some sections of a wooden window sill that a Pitbull ate. I still have the rental house, and the window sill is as solid as it was then. I also used it to repair superficial termite damage (after tenting the house).

[Bruce Wrenn]

A guy told me once that he bought some to work on his car with. He got a gallon can. It was a nice warm day. He mixed the whole batch up, and then went in the house to eat lunch before he started to work on the car.Did a job once using anchoring cement. Told helper to get water from drinking fountain to mix it. He got water from hand washing station, and mixed it. To say the least, it made a"cute little mound" when I tried to pour it out of mixing pail.

[Tom Bender]

No I wouldn't expect it to work well with glue, have to test that. I have used it as filler/glue where glue strength was not critical.

And my garage floor has some spalling and stone pits from salt and freezing. Plan to epoxy it someday but in the meantime I have patched with any excess Bondo I have mixed up. It holds up perfectly some, 20 years old. (maybe next summer I'll get to that project)

[Ollie McDottie]

I was a scenic in tv/min ovie art department for years some decades ago and bondo was our go to for so many things. The obvious was filling voids and cracks, because it can cure so fast, sands easily, and takes paint really well. Works really well with fiber glass too. The most interesting thing we ever did with it may have zero application to anybody here, but food for thought. For one job, we built these ornate picture frames with a plywood base and then poured A/B foam on top. This stuff bubbles up when mixed together and expands to some 30x times in a really cool way. Then hardens almost immediately. Once it fully cures after a couple hours, you can then sculpt it to whatever shape you want -- like carving wood, but foam. However, being foam it's porous and can't take paint, unless you seal it. So we took Bondo -- with very little hardener, thinned out with acetone to point it could be brushed on. then applied it to all the surfaces. Dried in little time and was paint ready pretty quick. These frames got banged around a lot on set, and to my surprise, after three season of a tv show they still looked really good. I've used this same technique sealing plywood cabinet/shelves, where the final look needed to be smooth and plastic like.

[Johannes Becker]

I used Bondo to fill in the edge of plywood before painting. It was a slight rounded edge and worked beautifully for the preparations. It was a piece of furniture for my daughters room. The one surprise came with use: when the edge got some nicks they showed as in the bondo pink on white. I first though my daughter had gotten some nail polish on it... something to keep in mind. For the repairs I now used some white 3M glazing putty.

[Erik Loza]

At the tropical fish store I worked at in college, this contractor built large plywood sumps to house the filtration equipment. Used a TON of Bondo to fill in the voids and to smooth out the fillets before laying up the fiberglass. Held up great from what I can remember.

Erik

[Mark W Pugh]

When you say "Bondo", which animal are you actually talking about? There seems to be a plethora of different kinds and mixes. I'm not real familiar with the products.

[Tom Bender]

Bondo is a brand name that gets used like xerox. I have used a few brands bought at auto supply stores. Those all seemed pretty similar. Open time is about 3 minutes so don't mix up a lot.

Is glazing putty as durable?

[Tom M King]

Consider that glazing putty has No durability, by comparison.

edited to add: When I first thought "glazing putty", I was thinking of glazing putty for windows. If you meant the auto body work glazing putty, it does have good durability, but it's not engineered for thick applications. It's just for filling in small scratches, and imperfections in body filler.

[Jim Dwight]

I recently used bondo on my front door. It used to have a mortise lock I did not want. So I removed it, cut a 5x4x1 inch piece of oak to fill the hole, glued it in with construction adhesive, and then used bondo on the thin areas on the surface of the door that needed to be filled in. The oak gives me strength in the door, the bondo is just for appearance. After painting, you cannot see the repaired areas. I also used it on a porch inner roof years ago and it held up fine under paint. I do not use it often but for painted work I think it is fine - for non-structural repairs.

[Frank Pratt]

And Bondo is also available with glass fibers for reinforcing, but it's horrible stuff to work with and is hard to apply in thin coats. The glazing, or spot putty will take a long time to dry & shrinks a lot if you try to apply in thick layers.

[dennis thompson]

I had a couple of porch boards with a little rot so
I called a guy to replace them .He said it wasn't worth replacing them and would just fill them with Bondo for $300😕, did it myself for about $10.

[Allan Speers]

TO the OP -

Maybe use Bondo in that way, but with a thin veneer of something like Hard Maple on the inside surface?
(Then carefully sand or rasp the whole thing to flat.)