I prefer using wire solder. To keep it clean, I take long lengths of
wire solder, wipe it down w/ some emory paper. Then I cut it into
short lengths about 1.5" long, and keep those short pieces in an
empty 35mm film cannister. Each film cannister is labeled as to hard,
medium,easy,etc. The solder stays CLEAN until you are ready to use
it. I used to hang the wire solder up on a board and wondered why
sometimes it would’t flow. Duh! The stuff got dirty being exposed to
air. Not any more since the age of film cannisters.
I use medium solder all the time to solder bezels onto sheet. Works
great! Hard solder to close the bezels, medium to solder them down.
If the wire solder is “blowing off” the piece, the flame is too
strong. Use a soft, mushy flame to make the paste flux tacky. For
filagree work, I’ve see flux powdered, then gently heated up to
preflow. It’s easier to nip off a tiny piece of wire solder w/side
cutters than taking shears to snip. I do use sheet solder for gold
work as that is more available. Yes, the solder pic is very good for
applying solder to an area. We just use a sturdier pic than what is
commercially available as the regular ones sag in no time flat.
Mountain Metalsmiths School of Jewelry & Lapidary