Paint or Bondo on lead

[Richard Lorenz]

I have some exposed old lead work. Will ordinary primers or sealers be O.K. to use directly on the lead? How about Bondo or equivalent? I don't want to remove the lead. Thanks, Richard Lorenz

[BRENT in 10-uh-C]

Rock & roll with it Richard. Just "texture up" the surface of the lead and it will be OK. I might also add that most epoxy sealers now can create a barrier if you are worried about acid leaching, ...and most fillers now are made for direct application over an epoxy substrate if you choose to go that way. We still prefer to apply any filler over direct metal. Just preference since we don't use epoxy on the outer sheetmetal areas.

.

[Craig Lewis]

If the lead is well adhered and smooth then treat it like any other metal and just prep that area extra well.
.....Here's how I've done it......
1) soak it with some metal etch/phosphoric acid solution and scrub with a fine wire brush or scotchbrite pad
2) wipe off the solution while still wet
3) dry the area well working in a heated environment or apply heat to be sure the metal isn't holding moisture.
4) sand or scotchbrite any dusty residue and immediatly apply a light coat of epoxy primer.
From here you can add filler or your choice of surfacing primers as desired.

[Craig Lewis]

Originally Posted by BRENT in 10-uh-C

Rock & roll with it Richard. Just "texture up" the surface of the lead and it will be OK. I might also add that most epoxy sealers now can create a barrier if you are worried about acid leaching, ...and most fillers now are made for direct application over an epoxy substrate if you choose to go that way. We still prefer to apply any filler over direct metal. Just preference since we don't use epoxy on the outer sheetmetal areas.

.

oops....Looks like I was typing (above) as you were posting Brent.

Q? Any significant reason you guys aren't sealing bare metal with epoxy?

[Terry, NJ]

Hi Brent! Since one doesn't have to worry about acid leaching out of the joint/seam with lead, does this apply to brass as well? And, will phosph. acid work under the epoxy fillers? What about Rustoleum w/fish oil? I've committed all of these sins on mine and I'm looking to make them right, but I have to know which ones are truly important or not. Keith True has stated that he read that Rustoleum doesn't make the "Fish oil" primer any more. And what they replaced it with is much more compatable to automotive paints. Have you heard this? And when was this subsistution made?
Terry

[Kevin in NJ]

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Some science on the above.

Paint sticks to scratches in the surface. Each paint has a particular scratch that it adheres best to so consult the tech sheets for the appropriate grit. Chemical etching also creates scratch.

In talking to the owner of SPI he explained how stuff adheres to epoxy primer. During the recoat window of epoxy paint the surface has micro holes that the molecules of paint are able to stick into. As the epoxy cures the holes close up locking the molecule of paint. BTW, this is also why using bondo filler direct to epoxy during the epoxy recoat window creates a very strong bond.

Also talking to the owner of SPI. The epoxy paint does not cure in the presence of an acid surface. So you can have a layer epoxy that is well cured except at the metal surface where acid has prevented the cure. Now you have no bond at the metal surface, but a nice shell of cured epoxy. The owner of SPI does not recommend any acid etchents as if you do not fully neutralize the acid then the epoxy can not cure at the surface. For those the believe in acid etching paints well pay attention at the shows looking for cars with failing paint where you see the bond between the acid paint and the next layer has failed. These paints are frequently incorrectly used and are the source of a lot of paint failures.

The Rustoleum paints are all bad because they are oil based and will constantly be shrinking, kind of like lacquer but worse. You end up with cracking as the layers of paint are shrinking at different rates. Even with all the same paints, the upper layer will shrink more as more oil evaporates at the surface and shrinks more.

Epoxy is strongly recommended direct to metal with bondo on top. This seals the metal and when properly applied the bondo will have a strong bond. BUT, laying down bondo direct to metal is just fine too. For a shop it is more labor efficient to level then seal. Since they are working through the stages rapidly it makes sense. A hobbyist tends to work slower. You may be much better off laying down epoxy to seal the metal as you spend the time getting stuff ready. Some guys it can take months or years to get the metal work down.

Epoxy paint must be sprayed when the temp of the part will be above 60 degrees or so for the full time the epoxy needs to cure. Once the epoxy reaction stops due to low temp it does not restart (again part of my talking to the owner of SPI).

Please keep in mind I am only reporting the facts as I have found them. I realize some people have other experiences. Please correct me if I am wrong. I am relying on what I have learned over the years and done my best to verify the facts and not all facts are easily verified.

[Craig Lewis]

Originally Posted by Terry, NJ

Hi Brent! Since one doesn't have to worry about acid leaching out of the joint/seam with lead, does this apply to brass as well? And, will phosph. acid work under the epoxy fillers? What about Rustoleum w/fish oil? I've committed all of these sins on mine and I'm looking to make them right, but I have to know which ones are truly important or not. Keith True has stated that he read that Rustoleum doesn't make the "Fish oil" primer any more. And what they replaced it with is much more compatable to automotive paints. Have you heard this? And when was this subsistution made?
Terry

I've rebuilt fenders with a torch in my "learning curve" years using metal patches and brass and it only lasted a few months. In a short period of time an outline of the brazed area appeared through the paint and body filler....in the right light you could clearly pick out every spot where the brass existed, even though the surrounding areas where perfect.
There was no holes left for moisture to creap from behind and I had sandedblasted the brass then applied body filler on top. Perhaps if I'd shot epoxy over the brass it would have not reacted?...regardless I've seen brass under paint bubble and react on a few other cars as well so I would not take the chance.

[Russ/40]

Originally Posted by Kevin in NJ

Some science on the above.

Paint sticks to scratches in the surface. Each paint has a particular scratch that it adheres best to so consult the tech sheets for the appropriate grit. Chemical etching also creates scratch.

In talking to the owner of SPI he explained how stuff adheres to epoxy primer. During the recoat window of epoxy paint the surface has micro holes that the molecules of paint are able to stick into. As the epoxy cures the holes close up locking the molecule of paint. BTW, this is also why using bondo filler direct to epoxy during the epoxy recoat window creates a very strong bond.

Also talking to the owner of SPI. The epoxy paint does not cure in the presence of an acid surface. So you can have a layer epoxy that is well cured except at the metal surface where acid has prevented the cure. Now you have no bond at the metal surface, but a nice shell of cured epoxy. The owner of SPI does not recommend any acid etchents as if you do not fully neutralize the acid then the epoxy can not cure at the surface. For those the believe in acid etching paints well pay attention at the shows looking for cars with failing paint where you see the bond between the acid paint and the next layer has failed. These paints are frequently incorrectly used and are the source of a lot of paint failures.

The Rustoleum paints are all bad because they are oil based and will constantly be shrinking, kind of like lacquer but worse. You end up with cracking as the layers of paint are shrinking at different rates. Even with all the same paints, the upper layer will shrink more as more oil evaporates at the surface and shrinks more.

Epoxy is strongly recommended direct to metal with bondo on top. This seals the metal and when properly applied the bondo will have a strong bond. BUT, laying down bondo direct to metal is just fine too. For a shop it is more labor efficient to level then seal. Since they are working through the stages rapidly it makes sense. A hobbyist tends to work slower. You may be much better off laying down epoxy to seal the metal as you spend the time getting stuff ready. Some guys it can take months or years to get the metal work down.

Epoxy paint must be sprayed when the temp of the part will be above 60 degrees or so for the full time the epoxy needs to cure. Once the epoxy reaction stops due to low temp it does not restart (again part of my talking to the owner of SPI).

Please keep in mind I am only reporting the facts as I have found them. I realize some people have other experiences. Please correct me if I am wrong. I am relying on what I have learned over the years and done my best to verify the facts and not all facts are easily verified.

Kevin, what consequences occur when you have finished body work, have epoxy sealed the surface, and do not finish paint for months or even years? This assumes the epoxy sealed surface has been lightly prepped for finish with a scotch rite.

[Tinbasher]

Hi Richard: I'm not sure of were you live but with lead your best bet is to sand it with 120 or 180 sandpaper and apply your primer. If your in a wet and cold climate I'd go with "Epoxy primer" first. This will improve the adhesion of your topcoats and add to the corrosion protection. I'm about 3 hours north of Buffalo NY. and by using epoxy I have paint work that's 20 years old that still looks good. The Old Tinbasher.

P.S. This Messchersmit 175 was painted over 10 years ago.

[Kevin in NJ]

Originally Posted by Russ/40

Kevin, what consequences occur when you have finished body work, have epoxy sealed the surface, and do not finish paint for months or even years? This assumes the epoxy sealed surface has been lightly prepped for finish with a scotch rite.

The instructions for epoxy were very clear. For epoxy past the re-coat window you must sand with appropriate grit paper (I do not know if scotch brite is correct- I have a feeling it is not). Recoat with epoxy and then put the next coat on during the recoat window.

I will add that epoxy is NOT UV stable. If the painted item was frequently exposed to UV then you might want to sand the surface better.

Now here is my assumption- that could be wrong.
You can sand with appropriate paper for the next coating. Remember that the modern 2 part paints adhere to scratches in the surface. Then spray your next primer. What I believe you lose is the super tight bond you get with the epoxy paint. You might also sand through in places and lose the tight seal. These are risks you take and done right it may not be much of a problem for our cars that are kept indoors. This is a short cut to save some money and my opinion (which could be very wrong) is it will not introduce any major problems.