old school "leading"

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Hello again fellas.  I've got a good friend in the auto body business that I do some welding for in my off time.  He was telling me the other day that he saw this leading process on a tv show once and this older gentleman was building a ridge down the center of a car hood.  He said it was an oldschool process that has pretty much been replaced by bondo.  Both of us being oldschool style junkies and my pursuit of metalwork I got very interested in it.  It seems though that everyone that I talk to their granddads did it but never passed it on so its a dying art. At least around here that is.  I was wondering if anyone had any info on it or were I might be able to find some.
Reply:Just used lead to hide some welds on a trailer fender a minute ago.  It's pretty rough stuff becausae it's just a trailer fender, but it's faster and cheaper than Bondo in small applications.  Basically, you coat the area to be leaded in paste flux.  Heat it with your acetylene torch and its smallest tip.  You need to use acetylene because propane wont conduct heat to the metal fast enough and you'll end up heating a larger area which causes more warping.  You're going to put some heat on and take your lead bar and rub it on the area with firm pressure while the torch is away from the work piece.  Repeat this process until you leave a shiny lead film on the area you want to cover.  This is called tinning.  If you don't do this part right, it will take too much heat to get the lead to stick as you fill it and you'll warp the panel.  Once the area is tinned, you just just a little bit of heat on the work piece to soften the solder you laid down in the tinned area.  Then, you take your bar and put the majority of the heat from the torch to it so it melts onto the area you just tinned.  If it beads up, the tinned portion isn't hot enough or you didn't tin it properly.  If it spreads out, you're in business.  Put a good amount of lead on and let it cool a little. It will take a fairly buttery concistancy as it cools.  Use a wooden spoon coated in parafin wax to push the lead around and into the shape you want.  Add more as necessary.  Work small areas at a time.  If you work too large of an area and put too much heat in, all of your hard work will just run off the side and onto the floor.  Rough it down with a coarse file or rasp or a flap disc on a grinder.  Finish it just like Bondo.  You must remove all of the flux after your are done or it will show through the paint.For more information, try Amazon.com
Reply:I did years of sheetmetal(still do some) and I use muriatic acid for the flux, and a few different torch tips. To keep the flux in line, I have used tape to form a start line. The tape will burn, but the cleaned metal will bond lead easily. I gree that working a small area will help a lot. Look for other specific tinning fluxes, there are tons out there. DO NOT get the lead going so hot as to vaporize. You gonna get brain damage!! Lead vapor will flat out kill you, or make your family wish it had.
Reply:Thanks fellas, didn't really think about that vaporizing thought.  I think Ill look for a book and see if I cant teach myself a little.