We all know it, we all love it, and the guy parked outside of the 7-11 covered his car in it. What is it? Polyester body filler, better known by the almost generic trademark, Bondo. There’s a lot more you can do with Bondo than fairing in that sweet body kit, bro, and [Eric Strebel] is here to show you how far you can push the mechanical properties of polyester body filler.
We didn’t always have polyester body filler. In the days before OSHA, auto body workers would use a torch, bricks of lead, and a grinder. You can check out a video of the era before OSHA here. Needless to say, vaporizing and grinding lead in your shop isn’t the greatest idea, and there had to be a better way. This led Robert ‘Bondo Bob’ Spink to invent a much less toxic auto body filler that we now know as Bondo.
For the beginning of the demonstration, [Eric] mixes up a cup of polyester body filler with a few special additions: he’s using printer ink to get his mixture to something other than that one shade of pink we all know. Although Bondo is a bit too thick to cast, he did manage to put a little bit of it in a square mold, a PVC pipe, and applied a little to foam and wood. It’s enough for a demonstration, but for the actual ins and outs of machining Bondo we’re going to have to wait until [Eric]’s next video. Until then, you can check out this introduction below, or look at his previous work on free-form sculpting of uncured Bondo.
29 thoughts on “You Can Build Anything Out Of What Is Holding Your 97 Eagle Talon Together”
The technique of using enormous amounts of lead to fill in dents is where the term “lead sled” comes from. Those old hulks weighed so much, it’s outrageous.
Most of the lead was smoothed by floats or spoons before the lead cooled. There was very little excess left, which was then removed by vixen files which removed the lead by s shaving action. Lead doesn’t sand well.
For large chucks of lead (ships ballast keels) a chainsaw works well too, which also uses a shaving action to cut.
That (going at a giant chunk of lead with a chainsaw) is probably the strangest image I’ve had planted in my mind from the HaD comment line. There must be some kind of prize for that.
Last day of school is coming up… Thinking on leaving a carefully painted lead or concrete football in the middle of the pitches for breaktime the day after
That sounded pretty funny at first as I imagined a lead american football. I imagined some jock getting a bit of a surprise when he goes to pick it up and it weighs so much more than he expects.
Then I realized that you mean a futbol (soccer ball). That’s not a funny prank that’s somebody’s shattered foot bones. Not cool, shame on you!
I detest polyester anything. The stench makes my head ace. I rather use Epoxy and Micro balloons, even if it cost six times as much.
If you ever made the mistake of buying POR-15, you can salvage a use for it by adding the micro-spheres and using it like bondo.
Only about twice as much (generic liquid epoxy about $60/gal vs. generic polyester bodyfiller $30/gal). And when you consider that there’s no significant odor, more definite mixing ratio, stronger, greater pot life, greater shelf life, etc., epoxy wins hands-down. I haven’t used bondo in over 40 years.
Um.. Yah.. epoxy looks like a material I would like to get familiar with. Except… that price. $60 / gal really is out of the range I consider practical for such things. It’s not that I can’t afford to pay that for a worthy project, don’t get me wrong. But.. every material is an investment in time and money just to get familiar with and then master it’s use. I would rather master the use of a material that I can stock up on cheaply and use whenever I have a creative idea or a need to fill without stopping to think of the cost and if this project is worth it or not. At $60 / gallon I would be constantly second guessing myself. “Should I really be wasting epoxy on this/that?” Then I would rarely ever make, repair or hack anything and the epoxy I save would probably go bad from age and really be wasted!
I do dream of the day when epoxy or something like it exists at that $30/gal or better yet even lower price. That will be a great day!
Some distinct differences between different epoxies.
Watch out for blooming or non-blooming epoxies.
And anti-sag powders, micro-speres, etc..
I’ve been wondering about using polyurethane ‘construction adhesive’ as an alternate material, in between polyester and epoxy, particularly where I’d be applying a fillet. With rigid vs. slightly flexible construction adhesives available, it gets even more interesting.
You can build anything out of that stuff that if you use you’re either a classic car collector doing a lot of stuff wrong, or making everyone around you double-check their alarm and locks..
By the way even when used correctly(most people don’t even use a cleaned surface-metal) it’s still no substitute for actually replacing the metal.. Shops love to use this stuff(“hack and pack”) and then tell you they replaced the metal to profit exponentially off their labor..
Who restores a re-branded Mitsubishi Eclipse? lol those are basically ghetto hot rods like civics and preludes..
“Grind an fill” is the term used around here (Chicagoland area), you are right if you use that stuff on certain classic cars…
Also consider using Bondo honey an gorilla hair as additives, honey thins the mix, hair adds fiberglass strength…
From what I have seen when I have driven to Chicago fixing something with Bondo is a luxury. It seems to me that most people just keep on driving and never repair accident damage at all!
Places where roads get salted a lot are famous for completely rotting cars out, and it doesn’t seem to matter what tech manufacturers use for urethane(most durable car paint) paints and clear-coat, or how much epoxy coating or waxing the car has..
Yup. Nothing survives long in New York State.
Go to the South and cars last forever due to no road salt.
Or you could buy fibre-mesh concrete additive from your local cement plant. One bag is added to a full cement truck so it goes pretty far for 10.00 or so (it’s about 4 cups packed. Personally I like using durabond 90 ( drywall mud) and window screen or chicken wire. Depending on the project. A structure of styrofoam covered with mud and primed and painted is quite strong.
“Although Bondo is a bit too thick to cast …”
Most of these fillers are just polyester resin with a crap load of bulking agent mixed in to make it thicker. (IIRC a rep once told me it was talc), so just add some resin to the filler to make it more suitable for the application.
We also used to do it the other way around, adding filler to resin to make a thicker gel coat for making fibreglass moulds. Sometimes the standard gel coat was too thin especially for details on the vertical sides.
This guy talks about the Bondo being too thick for certain applications, and goes to the trouble of trying to tint it with ink and such. All you need is some polyester fiber glass resin. The three additives you want on hand are: milled/chopped fibers – for strength, thixotropic silica – as a thickener, and glass microspheres as a low-weight volumizer. Microspheres and a little bit of thixotropic silica will give you your lightweight Bondo-like filler that’s easy to sand on, but you can dial in the thickness and cure time to your specific application. You can’t do that with Bondo.
Dipping his raw finger in the solder paste made me cringe. Both the flux suspender and the lead balls are toxic when ingested. Both are very difficult to clean 100% from ridges and pores in your skin – especially finger-tips. I hope he doesn’t eat his lunch ham sandwich with that unwashed hand.
I was horrified by this until I realized how much lead dust flies into the air from the filing step he didn’t show…
I guess he’s lived to a rip old age though. So maybe lead is his super-hero mana of choice. /shrug
Realistically, we know what the symptoms of lead poisoning look like, so it would be fairly easy to tell if someone had them. As far as I know, it’s not some lurking risk factor that shortens your life without showing symptoms.
“someone with elevated lead levels may have no symptoms.”
“the lead levels at which symptoms appear vary widely depending on unknown characteristics of each individual.”
“Authorities such as the American Academy of Pediatrics define lead poisoning as blood lead levels higher than 10 μg/dL.”
“In adults, symptoms can occur at levels above 40 μg/dL, but are more likely to occur only above 50–60 μg/dL”
“Death rates from a variety of causes have been found to be higher in people with elevated blood lead levels; these include cancer, stroke, and heart disease, and general death rates from all causes. Evidence also suggests that age-related mental decline and psychiatric symptoms are correlated with lead exposure.”
So in other words, every single thing you said is 100% incorrect. Realistically we don’t know what the symptoms of lead poisoning look like because many people with lead poisoning don’t show any symptoms. Accumulated levels of lead are most certainly associated with shorter lifespan and a significant decline in health.
Lead poisoning isn’t bad because it kills you, it is bad because you won’t notice any symptoms, you’ll just be 15% more likely to make choices that harm yourself, including committing stupid violent crimes where you weren’t even trying to achieve anything rational you just freaked out and all your friends went on TV and said, “Golly, this isn’t the real CaptMcAllister we’ve known all our lives, it was like he suddenly turned into a different person. I hope he can get the help he needs while he’s in prison!”
Look at crime rate maps overlaid with lead pollution maps. And then consider that most of those people do not have a high enough level of lead for doctors to consider it lead “poisoning.” There is no way to find symptoms in an individual, but at the community level the symptoms are obvious and striking.
Bondo is a threshold substance. Once you start playing with it, the porosity and lack of tensile strength will harsh your mellow, and you’re on a slippery slope down to polyester resin, then into serious epoxies, micro-balloon fillers, fiber-reinforcements (chopped/mat/fabric). Pretty soon they find you hiding out, drooling into the West System catalog and Burt Rutan’s books. Then the worst — repairing aircraft parts and making sailboats…for fun. It’s a sad fate.
As far as paddling lead, the guys who could do this are much treasured, but their disregard for the toxicity of the stuff is striking – when I was little, the guys who did this at the local GM plant (filling body seams during assembly) were sort of…grey, from the sheer quantity of the stuff they handled. Most were heavy smokers too.
The good news is that the push for lead-free solder in electronics has made lead-free body solder a thing, so we may see good restorations done with it in future.
Bondo may or may not be thicked by talc, but most of its differentiation from resin is glass microspheres.
There is a downside to Bondo/Lightweight filler, aside from the toxicity: polyester resin absorbs moisture, whereas epoxy resin largely does not.
We all had smoker’s cough, but few of us smoked, former body shop employee.
so, i don’t know anything about bondo, and the article didn’t help much, but the comments give me this idea…
is bondo to epoxy as lightweight spackling is to plaster?
bondo is a scam, in the same department as undercoating and extended warranties. Your first clue is that you’ve never heard of any of the companies that make it. Also, it’s only available at auto parts stores, where none of the employees have any clue about its toxicity or other properties. The whole idea is that the toxic fumes destroy your brain cells before you realize what a stupid mistake you’ve made.
You can mix Bondo with casting resin (and the amount of catalyst appropriate to the amount of resin your added) to create a Bondo of any density you want, so yes, you can cast with it. I’ve done it.
I laughed inside when I saw the title… I have two non-running Eagle Talons sitting in my driveway, both in need of some Bondo. One is a ’95 and one is a ’96. Sadly, no ’97.
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