Hello Pete
First the term silver solder is used by so many people for such a large number of compositions that it becomes misleading to use the term. Some people refer to the alloy of 95%tin and 5% silver melting about 450F as silver solder or phosph copper which has about 6% phospher 0 to 15% silver the rest copper melt around 1200F to be silver solder others think it must have a min of 40% silver to be called silver solder. Alcohol does not cause pits in silver. Have who ever told you that alcohol causes pits in silver solder to explain what composition he is referring to. I have been working with silver solder making things for over 40 years. I use so much that I just make my own. I like 75% silver 19% copper and 6%zinc. It gives me the ductivity similar to copper so I can hammer curved shapes and anneal at 1400 and not reflow the solder, it is very strong. Now welding technology is so advanced that I Tig weld most copper that is 48 oz or heaver. My tig is a Miller inverter with pulser control.
Moe