Bondo over primer? Will it stay?

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its best to treat the bare metal with a good epoxy sealer or primer that was made for bare metal before putting the bondo on. is it just a pin hole youre trying to fill? bondo was made to fill inperfections in the surface it wasnt really made to fill holes,jeff

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As previously stated, bondo is not for stuffing in holes. Here's what I'd suggest ....

With some sheet metal screws (wood screws will do in a pinch) secure some sheet metal behind the hole - as mentioned, a street sign does work well.
With a large hammer, pound the repaired area in so that the heads of the screws are below the body line.
Apply a sufficient amount of bondo to level the body panel.
Finish as desired.

Remember, a paint job is only as good as the bodywork underneath.

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The last line REALLY killed me.

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Wow, good job guys. Passing judgement and sentence after one post that doesn't even describe what he's working on.

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I'm a big fan of that expanding foam in a can. Just fill in the entire hole with it making sure that you have enough that it expands through the hole. After it hardens, you can sand it and shape it to the contour of the metal around it. A little glaze, a little primer, and it'll be as good as new. As a side benefit, it also provides some insulation in that area of the panel.

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I had a buddy do that to a 78 -79 volare to get it thru inspection...although he just cut it w/ a big knife and sanded it down flat and spray bombed right over it/

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If you put bondo over primer, will it stay? Or does it have to be strictly stripped metal?

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"OK--Here's the gospel on body filler/bondo over primer. I used to work as a technical/sales rep for the company that makes rage filler. I know the guys (chemists) that developed the resin for rage filler. I've been a bodyman/painter,sales rep and technical rep for 30 years. The resin in rage and other body fillers is fiberglass (polyester) resin. Today's resin technology makes the adhesion of these new resins as good or better than most epoxy adhesives (glue). They are designed to really stick! Also they are somewhat flexible when used properly. Most or probably all filler manufacturers design and reccommend them to be used over clean and prepped (grinding with course-36 grit) and rust free (sandblasted)and dry (free from moisture) BARE metal. They will stick to epoxy primers with mechanical adhesion-they DO NOT chemically bond with epoxies. If you put filler over epoxy primer it has to be fully cured with no solvents (thinner-reducer) left in the primer and still should be sanded with a course grit and cleaned. In other words- It's a wasted step that may or may not cause adhesion problems later on."

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I did not know using bondo was a sin? If the hole is deep enough with enough contours and you think it will stay in there then good. Go with your gut feeling. You treated the metal down in the hole so it should not rust anymore (theoretically). It's your ride do as you wish. My ride may not be perfect to some but I will be the one having some fun. Jay Good luck with your project I know I'll need some.

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I did not know using bondo was a sin? If the hole is deep enough with enough contours and you think it will stay in there then good. Go with your gut feeling. You treated the metal down in the hole so it should not rust anymore (theoretically).

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I don't think rust would be the problem. If bondo is simply used to plug a hole of any size, without something for it to hold on to besides the circumfrence of the hole, is not matter of IF it will hold; it will eventually break out. Unless of course you put some newspaper or rags behind it

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I was going to suggest some waded newspaper, or perhaps doing the repair correctly using and old street sign to fill the hole?....I don't know why he's using spraycans?.....a paint roller works just fine, maybe even blot it on with a paint sponge from HomeDepot.......perhaps you use this technique too?.......hence the need for

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When the fixed the Levey that broke in new orleans they stuffed the cracks with newspaper at the expantion joints and then spread some sealer on it! Since they were out of what they were supossed to use

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.....Honorable (dishonorable?) mention goes to the guy who suggested squirting in the expanding insulation...I got a laugh out of it, but I can't see doing that. ......

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Thanks for the advice, all. Just for good measure, I decided to take some shots of the holes in question:

Drivers side (shot 1)

Driver's side (shot 2)

Passenger's side (shot 1)

Passenger's side (shot 2)

These I think I can slip a little sheet metal behind.

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With all the critisim here (even though some of it was just for fun) there has to be a memeber of the board that lives near this gentleman to go and weld a quicky patch in for him. I know i would if i lived close.

To the original poster, maybe place an ad on this board in an appropriate section asking for someone to help you weld a patch in. What you have there and the way the proposed fixes would happen, your are probably not going to be happy in the long run with all your time, money and fustration to fix it second rate as opposed to giving someone $40-50 to weld in a couple of patches. Of course this is just my opinion.

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fix it right the first time...
but everyone missed the original post...
bondo over primer...go or no go?

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