https://youtu.be/P2_jqOedtjU
RWTF, Hi, couldn't think of a way to describe it but the wonders of modern technology should help. It's a water tight folded joint in sheetwork.
Lead burning is a lowish temp weld using a propane or oxyacetylene torch and lead filler rod. It's tricky with thin sheet as it's easy to hole through so you've gotta move quickly. It was used more in the chemical industry for chemical vessels (acids etc) until modern plastics took over. It's a dirty job and leadburners needed regular blood tests as the fumes let lead into the body via the lungs, once there were so many ppm in the blood, you had to stop working with it so probably a good thing it's not so common now.
I've done a bit when a downspout or drain pipe needed to be fixed in a lead gully but again, it's not so common now with modern materials.
Hope that throws some light on it.
Cheers
Nick.

Last edited by Nick. C; 04/16/19 11:24 AM.
Rust never sleeps !