Jo,
I use 63 tin/37 lead soft solder wire that’s eutectic and melts at
361 degrees F. I couple it with Superior #30 Soft Soldering Flux. I
use some 0000 steel wool to clean the solder before using it.
If I find the residual lead to be a bit stubborn when removing it, I
may use a piece of moistened hard felt with Wright’s.
Jeff Herman