In 1955 "Bondo" came out as the first plastic body filler and made fixing imperfections in metal much easier than before. Today fixing dents and smoothing imperfections in a body panel has been simplified to where it's almost as "easy" as mixing two bits of putty, applying it to the panel, and sanding it all smooth. Before those days the only option was the process of "leading". During this process you melt sticks made up of mostly lead and a small portion of tin onto the surface. With the invention and evolution of plastic body fillers the art of leading a body panel has been slowly dying out, but if you want to keep "traditional" or true to the era of the car you're building; leading is the only way.
Only a few guy from the golden age of kustomizing and hot rodding are still with us, and even less are still working on cars. One of the best is Gene Winfield and even today, well into his 80's he's still traveling the world kustomizing old cars and teaching classes about metal shaping, leading, and anything you want to know about custom cars. I was lucky enough to catch up with him at one of his recent metal working seminars to get the process he uses to apply lead to a panel.
Gene is a long time Eastwood customer and supporter. In fact he use Eastwood leading supplies and claims we have some of the best products to apply lead on the market! Aside from an Oxy-Acetylene torch, below are the basic supplies you'll need to lead a panel. We'll explain each as Gene shows the process.
The first and most important part you need is for your Oxy-Acetylene torch and is a diffusor tip for body soldering or leading. This tip slips over your pre-existing torch tip and allows you to use only Acetylene to produce a soft flame that is easier to control when leading or soldering a body panel. The gas should be set to about 10-12 PSI before lighting the torch and fine-tuned once the torch is lit.
Once the torch is burning properly and you've cleaned the work area down to bare metal you can open your tinning butter to "tin" the panel. Tinning butter is like the "glue" that allows the lead or body solder to adhere to the panel and not just run off. Gene says he actually prefers the Eastwood compound because it is thicker than all the others on the marker. Our tinning butter has been specially formulated with thickening agents that gives the tinning butter a paste-like consistency that makes it much easier to apply. Gene advises to use a common household copper cleaning pad like you'd use for pots and pans. These can handle the heat involved in the tinning process and are easy to replace when they go bad. First you want to heat the panel with your torch to burn off any contaminants and also so that you can melt the tinning butter onto the panel. The key is to heat the panel just beyond warm but NOT until it is red hot. As you heat the panel dip your copper pad (hold the pad with pliers for safety!) into the tinning butter and wipe the panel with the tinning butter-coated copper pad. The panel should take on a "shiny" silver finish as you tin the work area. Gene suggests to prepare an area a bit larger than where you need to apply the lead or body solder so that you can feather edges and there isn't a hard or defined edge where the body solder stops. Once the entire work area is prepared you need to neutralize the acid left from the tinning butter by cleaning the area with a baking soda and water solution. Clean the tinned area very well as any areas left untouched will have an acid in them that can tend to come through the coatings over time and cause primer and paint failure.
The last picture above shows a properly tinned and prepared panel for lead or body solder. Now you are ready for the fun (and tricky) part of this process, applying the lead or body solder. Before you go melting your filler rods and making a mess you need to properly prepare the paddles for smoothing the lead. Most of these paddles are made of wood and vary in size and shape depending on the area you're working on and your personal preference. Unfortunately lead and body solder like to stick to a dry paddle and can make a mess. To stop that from happening you need to lubricate the paddle so it will glide over the lead and easily smooth it out. This is where paddle lubricant comes in. Quality paddle lubricants should be made up of a portion of either bees wax or animal fat. Either one is acceptable and it's a personal preference on which you prefer. Our tallow of lubricant that Gene is demonstrating with is an animal fat based lubricant.
Gene uses a pretty unique method to lubricate his paddles. He takes a piece of jean material and lays it out next to the tallow of lubricant first. He then waves the torch over the lubricant just enough to melt the surface and digs a small dab of lubricant out of the tallow and drops it on the jean material. He then quickly waves the flame over the small dab and spreads it out into the jean scrap. Gene explains that you only want a very thin film of the lubricant on the paddle and by rubbing the paddle into the warm, lubricant-soaked jean scrap you're able to apply a fine film instead of dipping it into a puddle of lubricant. The other upside is that you can save lubricant by just having to reheat the jean scrap quickly and again rub the paddle over the surface to put another thin film on it.
With the panel tinned, and the paddle lubricated, we're ready to apply lead or body solder to the panel. The technique for applying the lead varies greatly. I've commonly seen guys that will heat the panel and twist globs of filler into the work area, then reheat and smooth with the paddle, but Gene has a slightly different, technique. Gene starts by again heating the entire work area up until it is just a bit past warm and then begins melting the filler rod into the panel. He prefers to lay the rod at about a 45 degree angle and heat the end of the rod until it turns to a soft "plastic" like consistency and then allows the filler to lay out in strips until it is stuck to the panel. After Gene gets the filler rod melted to the panel he again goes back and reheats the work area and then goes back into the filler he's laid and reheats it until it is into the plastic stage again and begins to slowly dab and push it outward with the lubricated wooden paddle. This part of the process really takes some practice to balance the heat of the panel, the body solder, and calculated movements with the paddle to efficiently push the filler around and smooth the surface out. The nice thing about body solder or lead is that you can take as many shots as you want at reheating it and smoothing the surface further.
When I asked Gene about lead-free body solder vs. true lead filler he explained that it works ok, but is more difficult to control as there is less time between the filler rod being in the soft plastic stage and turning to a liquid and running off of the panel. He suggested that anyone learning to use lead-free body solder should begin by practicing on a flat panel to make the process a little easier.
With your first round of body solder or lead added to the panel and "roughed in" you can recheck the panel and see if you need to add anymore filler rods to the work area. During this process you may need to lubricate the paddle again if you see the filler beginning to stick to the bottom of it. Gene also showed us an advanced technique for vertical panels where he used the backside of the torch to push the filler rods into the panel before reheating and smoothing them into the work area. It sure looked difficult, but he assures me it can be done with some practice!
Once you have the lead smoothed out onto the panel you can take a flat or half round body file and start knocking the high spots down until the area is smooth and ready for primer and paint. Lead IS in fact dangerous for prolonged exposure or to breathe in. We suggest a respirator and gloves during this entire process, but especially when you're filing it down. Lead Free body solder can be treated more like plastic body filler and you can use a DA sander or grinder to smooth the area out. But because lead is so toxic, you do not want it floating around in the air when you sand it to a dust using a sander.
I'm very thankful that Gene was willing to share this process with us and give some insight on the art of leading. I'd highly suggest attending one of his classes if he is in your area, they're worth it! Be sure to check out our full line of body solder and leading supplies including all of what Gene used in this demonstration here: