I was attempting to solder a piece of sheet brass around a brass form, I tinned the sheet but I found the sheet difficult to follow the form so I then annealed the brass sheet. During the heating process the solder ran to form blobs I then tried to scrape off the solder but found it was very hard, then started to file the solder ( which I would normally not do) the solder was as hard as steel.
I have not encountered this situation before, could it be the lead in the solder had been burnt off thus leaving just tin? Anyone got a thought on what happened.
Mike