Silver Soldering

[thomasedwin]

I'm looking for a 100% lead free silver solder, that you use with a regular map gas torch. I plan on building a copper shotgun condenser for purifying alcohol. I am an old school plumbing solderer. I have been using oatey lead free silver solder. In a 3 inch diameter pipe solder joint, I make the solder connection then I soak the whole pipe in a bath of concentrated citric acid to clean the copper pipe and solder joint. The problem I have is when I clean the copper it gives the silver solder a dark grayish black residue that has to be wire brushed off and it's hard to get it all off especially on the inside joint where you can't reach, not only that but the solder never stays bright and shiny. Over time it turns to a dull finish and has to be cleaned again. I'm looking for a 100% lead free solder that makes a strong joint and it stays a bright silvery finish. Does anybody know of a good solder for this? After cleaning with citric acid I rinse it with a baking soda water solution and when I clean and apply flux for soldering I use a strong liquid acid flux. Be specific.