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Fri Jun 26, 2009 6:20 am

I was just wondering how tough and how long will this stuff last....can it stay on the metal for decades? :shock:

Fri Jun 26, 2009 6:30 am

Generally the metal around it rots away and the chunk of bondo just falls off.

Fri Jun 26, 2009 7:09 am

Bondo...and all polyester based body filler should be avoided at all costs. It entrains oxygen. That means that sooner or later it will rust...always. As Glenn noted....its downhill from there.
Bodywork guys that I have met who are good....tell me that its really only long term safe (debatable)...in very very thin sections of like .010" to .020" thick or less.

I have been playing with some Eastwood low temp, lead free sandable body solder. That is what I am going to be using because it does not corrode if sealed properly and does not entrain oxygen and moisture like Bondo. Ray

Fri Jun 26, 2009 7:25 am

raygreenwood wrote:
I have been playing with some Eastwood low temp, lead free sandable body solder. That is what I am going to be using because it does not corrode if sealed properly and does not entrain oxygen and moisture like Bondo. Ray

Where do you get this stuff and how do you use it? Thanks!

Fri Jun 26, 2009 7:53 am

try googling eastwood paint or body filler.

any good body and paint supply store can get it for you

Fri Jun 26, 2009 7:56 am

http://www.eastwood.com/autobody.html

Look down the page at their body solder kit.
In general, you use body solder in sticks and bars. You heat the area with a propane torch and apply the solder to it.

before you get antsy about the ehat issue...realize that we are talking about probably 1/3 to 1/4 the heat of welding. Mybe 600F tops. Yes you get some expansion...but not permanent expansions likeith welding.

The object I am finding is that you can surround a panel solder area with a water drip tube for cooling or wet rags (especially in large wide panel areas like the rear quarter of of type 3 or 4)....to keep it cool.

Large holes of cut-out...you can either tack weld sloppy thin steel sheet just inside of the hole below the surface and then its easy to fill solder on top....or use copper sheet as a temporary filler (like under trim holes you want filled)....and then flux everything and solder. The copper sheet then pops loose.

After that...it works pretty much like regular body filler...'cept its metal. You can sand it with no worries as long as you use the lead free ...or with a dust mask and gloves with the leaded version. I'm just starting out with it....but it seems to be the sweet way to go for trim holes and rocker panel...any non-structural repairs.
I will also be trying it f or limited pin hole repair on floorboards. Ray

Fri Jun 26, 2009 8:09 am

We used American Stripping here in Sacramento for our media blasting. They use a primer afterwards that hardens like POR15 then the body shop used a light bondo coating where needed. I have seen some buses in wrecking yards with bondo that was put on 25 years ago and there is no rust so I think it matters more how it was prepped. One cannot put Bondo onto rust and expect it to stop the rust. American Stripping has a new process where they spray a molten Zinc alloy onto any rust damaged areas where it attaches and builds up. It is then ground down and the area becomes as one. You would have to see it but if both sides can be reached, whole areas can be restored. We are blessed here in Central and Southern California to not have the rust issues the rest of you do.

Fri Jun 26, 2009 10:52 am

The molten zinc...is exactly what body solder is. Its a zinc alloy. Its not as hard as steel...but is lots harder than bondo...so yes...if you support temporarily from the rear....through a big hole...I mean even like 6" square of rusted metal missing....you can solder straight across in layers...and basically just sand it out. Yes...replace whole panel sections almost. Ray

Fri Jun 26, 2009 11:11 am

American Stripping uses a special screen as a base for the molten zinc alloy when the hole is big. You can take a screwdriver and tap the metal when it is done and it rings just the same as the nearby original steel.

Fri Jun 26, 2009 1:09 pm

That exact thing is what actually got me sold on body solder over Bondo. Ray

Fri Jun 26, 2009 2:04 pm

Bondo is polyester, same thing thet make corvette and boats out of (with fiberglass reinforcing). Polyester doesn't stick well to stuff. That's why they have no trouble popping boats and corvettes out of the molds.
Epoxy on the other hand sticks very well to stuff, and it is waterproof so that moisture won't soak through it and cause rust from behind like bondo.
Epoxy is much harder to sand than bondo, is more difficult to paint, and much more expensive, but will make a lasting repair.

Fri Jun 26, 2009 3:40 pm

My Dodge pickup has a Bondo repair that was on it when I bought it way back in 1982. The Bondo is still there 27 years later, can't say as much for the floor boards.

Fri Jun 26, 2009 5:46 pm

Blood Loss wrote: Bondo is polyester, same thing thet make corvette and boats out of (with fiberglass reinforcing). Polyester doesn't stick well to stuff. That's why they have no trouble popping boats and corvettes out of the molds.
.

uhh, it pops out of its mold because they use a spray-on mold release compound. try dropping a blob of bondo onto unsanded paint. sticks like a muhfugger. it isnt JUST polyester- it has an epoxy component to it. thats why it's a two part mix.

Bondo durability depends all on how you prep it and use it:

1) ideally, have someone grind the metal as you mix the bondo, then let NO time pass before you put it on. the longer the ground metal sits before application, the worse the rust will eventually be.

2) be sure you use a new grinding disc (36 grit) for each bondo application. the price is small and the difference in adhesion results is drastic. the abrasive gets dull almost immediately- after that it cannot cut scratches with sharp peaks and valleys.

3) do not overmix the bondo and hardener

4) do not use too much hardener- too much, or overmixed hardener has an effect on the resilience of the bondo- which is needed as the metal expands when heated. this is the same reason why adhesion or the bondo itself will fail if applied thicker than 1/16"- thicker layers are less resilient.

5) to minimize the rust issue, apply in the low humidity conditions and be sure to seal the bondo with primer once it has been sanded to its final contour.

6) Very important! - be sure to squeegee the bondo into the freshly ground metal from several different directions before building it up to final thickness. be sure all the ground metal scratches are going the same direction and approach the scratches with the squeegee at a 45 degree angle to avoid incorporating air bubbles. use lots of pressure when you squeegee it on- to work it into the scratches- it is this boundary layer that determines the adhesion.

7) do not continue to spread the bondo if it begins setting up. if you have too much on there at this point, just stop spreading and sand off the excess. if not, then sand it all off and start again.

8 ) do not sand the bondo before it has hardened adequately. once it does, sand quickly- it continues to harden as the hours pass. if you cant finish the sanding of any given application by the day's end then dont even start it, as tomorrow the bondo will be hard as a rock, and you will think you are sanding a rock :shock:

9) do not mix your bondo with a stick. use a spreader to avoid incorporating air bubbles. when mixing, the scraper will first touch unmixed bondo. about halfway thru the mixing, you need to scrape the unmixed bondo off the surface off the mixing spreader. i use a cardboard edge for this.

10) do not use the same spreader for both mixing and applying.

many people contend that bondo should be applied over freshly applied epoxy primer. this does solve the rust issues, but it does supposedly compromise some immediate adhesion, or at least thats what i have heard. but then if it doesnt rust, the adhesion years later might be better than the ground metal application method. disclaimer: YOUR CHOICE, I AM NOT TAKING SIDES! i refer y'all to the paint/body section of the sambaforum in the event any of you decide you wanna get loud with me about this controversy.

Fri Jun 26, 2009 8:37 pm

/\ /\ /\ This man knows his stuff! /\ /\ /\

Fri Jun 26, 2009 10:50 pm

The only experience I have with bondo is sanding it off my bus. Musta been several inches over several square feet. I hid one small dent and lots of rust. The suspect the rust was do to improper prep like others have said. But I dislike it and have no intention of putting any back on my bus.

The neat thing was finding the repair paper work in the bus. The work was done in the early eighties.

Fri Jun 26, 2009 11:03 pm

Dan's the man!!!!!!!!

Fri Jun 26, 2009 11:49 pm

its not so much that ne knows his stuff, which he does, but that he clearly states what he knows and what he heard. I have removed several bondo repairs from my bus to find shiney metal underneath, was shocked adn impressed, but also have found bondo repairs when the sheetmetal fell off from behind, leaving only the inch thick bondo, which I hten snapped off. so there appears to be much in the prep work. me, I would sand, seal, bondo paint. would rather reapply bondo than chase rust every couple years.

Sat Jun 27, 2009 3:15 am

fusername wrote: its not so much that ne knows his stuff, which he does, but that he clearly states what he knows...

you mean this part?

dansvans wrote: sticks like a muhfugger.

:lol:

Sat Jun 27, 2009 3:58 am

knowledgeable and eloquent, what more could you ask for?

Sat Jun 27, 2009 4:00 am

free parts :lol: