| Leadwork 101
The quality of plastic fillers has progressed immensely since their introduction and are in my opinion a better option than lead in most cases. Keep in mind that both lead & plastic are both fillers and their use should be minimized by proper metalwork.
While lead or body solder has been all but replaced by plastic fillers, there are a couple situations where I feel lead is worth the extra trouble & expense to use…
When filling is needed on the edge of panel where it may be subject to bumping, lead is preferred.
The other place I insist on using lead is on the roof seams and rocker panel to quarter joints. These seams are vulnerable to “telegraphing”. A condition where the seam becomes visible in the hot sun. It’s caused by differences in expansion of the different metal thicknesses and stress differences of the panels. Use of any plastic based filler will not stop it!...This includes All Metal, Metal-To-Metal, Tiger Hair, DuraGlas, any ‘glass strand fillers, etc. The only cure I’ve had success with is to lead the seam.
Leadwork can haunt you if it’s not done exactly right. Every step must be done correctly.
Now for the details!:
Please wear proper respiratory & eye protection…
1. The seam should be MIG welded solid. Because of original solder residue under the
flange, TIG welding won’t work well. Vinyl top cars didn’t have body solder on the
roof seams and are easier to weld.
2. The weld should be ground flat. No pinholes or other cavities can remain. You don’t
want any place for the prepping products to seep in or for condensation to invade
from behind the lead. This is the main culprit for the rust that is often found
under factory leadwork.
3. The weld & entire area to be leaded should be sanded very smooth. Grinding ruts and
coarse sanding marks are not desirable. 3M Clean ‘n Strip discs or Scotchbrite wheels leave a perfect shiny smooth metal finish.
4. Now wipe down the area with wax & grease remover.
5. Brush on Tinning Butter (as available from Eastwood Co.) liberally.
6. Heat the Tinning Butter slowly & evenly until it turns a dark brown color.
7. After cooling, wipe the brown residue off first with a damp cloth to remove as much as
8. Follow by scrubbing with a paste made using baking soda and water. This step is to neutralize any remaining acid residue and further clean the surface.
9. The last step before soldering is to wipe the area down with a solvent such as Glasurit
360-4 Metal Cleaner or equivalent.
10. The entire area to be leaded should now have a shiny tin coating.
11. Here’s the part where it gets tricky! Apply heat evenly over a couple square inch
at a time until a solder bar can be melted by the metal. You don’t want to melt the
bar with the torch flame! The solder is applied by melting it into the panel much
like putting out a cigarette. Warm the panel, remove the heat and push the bar on.
This is repeated over the whole area until enough solder is applied to fill the area.
12. The last step is to re-warm the solder until it gets just to the “plastic” stage.
Too much heat and it will run to the floor; not enough and the paddle won’t move
the solder or it will crumble. The paddle has to be coated by melting wax in a
tub and sliding it into it. “In the day” oil was used, but the wax works much
better. In this step it’s important to heat the solder well enough so that while
spreading it, minimal air pockets form and that the coating all melts together.
13. The leaded seam can now be filed or sanded to shape. VERY IMPORTANT to wear
excellent respiratory protection!
The feather edges of the lead should be well adhered and not be able to be scraped
back with a fingernail. If it can, you didn’t do it right!
14. A perfectly filled seam isn’t totally necessary; the final touches can be done in a quality plastic
filler after a coat of epoxy primer. The thickness of lead will control the telegraph
problem I spoke of earlier in this article.