* The only flux I use is Acid Free, non-toxic, non-hazardous and water soluable. Very user friendly and perfect for soldered art.  No smelly fumes or messy residues.  Paint a little flux onto the copper foil tape, metal or solder to allow the solder to "stick" and flow smoothly.  .5 oz size with brush top lid, the same bottle that is included in the Soldering Starter Kit.