Barrie, Lead (Pb) is an element, when it is melted and re-solidified it is still Lead and of course still malleable.
It can be re melted and used many times over and will not change its properties unless contaminated by other impurities, oxides are easily removed by simple fluxing.
Old soft solder was a mixture of two metals, Lead and Tin, Tin helps to harden the alloy and improves flow and aids “wetting”. The latter we do not want, as it tries to bond with the copper pipe and makes it harder to remove.
Only use Lead for this application.
The problem is that “new” soft solder is not Pb and Sn, as Pb has been banned for use in most areas where it was commonly encountered.
Modern soft solder is now commonly a mixture of low melting point metals such as bismuth, indium, zinc, antimony etc. These are not good for our intended use of pipe bending, far too brittle.
Hope this helps, Mike.
