Posted by Neil Wyatt on 27/02/2018 23:06:41:
Yes. Even I can do it 
One approach is to heat bit red hot and let it gcool, this burns off surface carbon. Then flux, reheat and silver solder as normal.
Keith Hale's book goes into some detail on teh subject.
Neil
As Neil said but give the parts a good wire brushing to get rid of the ash/crud after it cools, I've used this method and it worked for me.
Stew