Megacast Self Pickling Flux It's the tried-and-true jewelers' hard soldering flux. Yellow-green and self-pickling, it is the best in water-based fluxes. Well-mixed to eliminate suspension. Use this hard flux on gold, silver, platinum, and other metals with higher melting points. It preserves temper and color of metal and the adhesive qualities of this liquid flux hold solder in place. The benefit of liquid flux is that its transparency will let you see the solder joint more clearly when soldering, and the liquid flows better in joints than a paste.