Lead burning

Lead burning is a welding process used to join lead sheet. It is a manual process carried out by gas welding, usually oxy-acetylene.

Lead burning is carried out for roofing work in sheet lead, or for the formation of custom-made rainwater goods, gutters, downspouts and decorative hoppers. Decorative leadworking may also use lead burning, particularly where a waterproof joint is required as for planters. Lead burning is thus part of traditional plumber's work, in its original sense of a worker in lead (latin: plumbum). Although rare and specialised, this work is still carried out today and not just for restoration of historical buildings. Most lead sheet work is formed and sealed by bossing, a mechanical fold or crimp. This is adequate for roofing that sheds water, but is insufficiently watertight when standing water sits upon it and so an impermeable burned joint is needed.

Lead burning is not used as part of plumbing work for installed pipework. Lead piping has long been considered obsolete, owing to the health aspects. Even where lead piping, or lead-sheathed cable, still needs to be jointed, this is carried out with a wiped joint, rather than a burned joint. Wiping a lead joint is a soldering process, using plumber's solder (80% lead / 20% tin) and is carried out at low temperature, with a natural-draught propane blowtorch. Today, even wiped joints are rare and where an existing lead pipe must be connected to, a proprietary mechanical joint is more likely to be used.

In some rare cases within the chemical industry, lead burning is used for pipework, where acid-resistant tanks and pipes are required to be made of lead rather than steel. Niche uses for lead burning include the manufacture of lead plates for lead-acid batteries and for electro-plating electrodes.

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