Cydrome Leader wrote in
rec.crafts.metalworking on Sun, 13 Mar 2011 21:48:15 +0000 (UTC):

What's a good way to keep solder from flowing or wetting copper or brass
parts being soldered- sort of like an anti-flux. I recall seeing something
posted here about it, but can't locate it.

It's called solder mask. You can get it in tape form from granger.

--

Dan H.
northshore MA.