Fillers for seams/welds

danp76

Oldtimer
Hi guys, what are you all using for skimming over welded seams? I typically sandblast my welds, epoxy and then glaze over my welds to blend in any grinding marks, etc. I have also used Metal to Metal and short strand fiberglass fillers. Is there something better for sale panels and welded joints to skim with? thanks guys!
 
I don't know but if you solid weld and epoxy does it really matter what you put over the epoxy?
If lapping and worried about swelling in sun that is different.
 
I just epoxy then fill over the epoxy with rage had no problems to speak of.

Same here!
My sail panels are lap joints, like they were at the factory, but these joints are so high on the car that they are not usually subjected to water, and seldom rust. I treat sail panels exactly the same as I do but welds, but my lap joints at the sail panels are more akin to butt welds, as I do not spot or plug weld them like the factory did, but weld the seal completely where the two panels meet.


Regards, John McGraw
 
My opinion about what to do with factory seams that had lead in them has evolved over the years. Personally I believe that lead done correctly is better than any polyester based filler. I have no experience with the epoxy based filler but I still think lead being a metal and water proof will last far longer. (if done correctly) Problem folks have with lead is that they don't know how to correctly apply it and then use aluminum oxide sandpaper over the lead. So screw ups, defects, happen with the lead and paint applied over it, and the lead gets blamed.
Done correctly, lead will last a lifetime. And if you observe proper safety precautions it is no more dangerous than spraying iso based urethanes.

On lower end stuff I feel any polyester or fiberglass filler will suffice. Lower end stuff is probably a good place to use epoxy based fillers (on factory seams) especially if you have to apply it fairly thickly, like at the factory roof to 1/4 panel seam on a Fox body Mustang. When I was rebuilding early on we did a lot of those cars and used polyester based fillers and a fair amount of them would crack there due to the amount of filler required. Didn't really seem to matter whether we welded the entire seam or plug welded it.
Just my opinion.
 
Last edited:
A not so great quality weld or a lap joint my benefit from an upgrade sort of filler, provided that the actual weld or joint area can retain a slight hint of thickness to the filler. Otherwise it's just sanded off or too thin to provide any other sort of possible benefit. A stranded filler usually really needs a finish filler over it & can really be a worse choice than standard quality polyester fillers alone. No upgrade filler will be a true fix for improper work in a critical show application.
Vette panel adhesive can be a good upgrade for certain situations, such as skimming a bonded on part in a custom application or wanting something tougher at bodylines for near an edge. Still not a bandaid though.
 
Chris, how thick was the filler applied that ended up cracking? I would think a skim coat would be fine.
I will have to address this issue on my '68 GTX when replacing the roof skin. That joint on the sail panel was leaded from the factory. I have never used lead before so a bit intimidated by it.
Roof Removal.JPG
 
I use CarboFil by SEM. Carbon fiber reinforced filler that remains a little flexible to resist cracking.

Don
 
Chris, how thick was the filler applied that ended up cracking? I would think a skim coat would be fine.
I will have to address this issue on my '68 GTX when replacing the roof skin. That joint on the sail panel was leaded from the factory. I have never used lead before so a bit intimidated by it.

Those Fox body's had a pretty deep trough where the two panels met. Around a 1/4 of an inch. Seen 1st gen Camaros do the same thing. Actually have one scheduled to fix that very issue. High dollar paint job and the filler is cracking at the trough where the roof and 1/4 panel meet.
 
Lead it . It's not that hard to do. Watch a few YouTube's is a on it . Just don't sand on it. Use a file .
 
Some things to consider when working with lead:
The base surface needs to be perfectly clean. Absolutely perfectly clean By clean I mean rust paint etc...
After applying the tinning flux you need to wipe it. Some wipe dry, some prefer damp. Use only clean 100% cotton cloths. Cotton baby diapers type cloth is preferred.
When you do the wipe it needs to be 100% perfectly shiny. Any black spots imperfections discolorations means you need to do the tinning process again.

After applying the lead you should use a body file to work it down. If you need to sand it only use silicone carbide paper NEVER use aluminum oxide paper. Typically silicon carbide is wet sanding type paper and aluminum oxide is typical dry paper. If you do use aluminum oxide paper it will embed in the lead and cause something called intergranular corrosion. This will show up in the final surface as lines similar to sand scratches. Years ago you could get away with using AO paper as many used a zinc rich primer over the lead.

When finished applying the lead, neutralize the area by washing it thoroughly to neutralize any exposed tinning residue. Some use Dawn and hot water, some use baking soda and water. Good idea if you have hard water is to use some store bought distilled water for this step.

Also bee's wax that is typically used to lubricate wooded lead paddles is not ideal. Tallow or beef lard is preferable due to it's neutral PH. Learned that from a Englishman who'd been leading his whole life. You can get it at your local grocery store.

When working with lead remember that both the lead itself and the fumes are toxic. Use a P100 rated respirator. They are affordable and available. Typical paint respirators are N95 rated and do not filter lead fumes. Sweep up your shavings as you are working. Remember that lead accumulates in your body over time. So you don't feel any effects right away. It's a long term process.
 
Last edited:
Great. Thanks for the info. Copied and saved to my Body Work file folder.
When I get to work on my car again the installation of the drip rails and roof skin will be the first thing I tackle. So will update that thread as I try my hand at lead work.
 
Chris, how thick was the filler applied that ended up cracking? I would think a skim coat would be fine.
I will have to address this issue on my '68 GTX when replacing the roof skin. That joint on the sail panel was leaded from the factory. I have never used lead before so a bit intimidated by it.

Good spot for Adtech P17
 
Great. Thanks for the info. Copied and saved to my Body Work file folder.
When I get to work on my car again the installation of the drip rails and roof skin will be the first thing I tackle. So will update that thread as I try my hand at lead work.

watch some gene winfield youtube videos . getting rid of the acid is a must if using spi .

eastwood is a good source for supplies .
 
Back
Top