Flux / Chemical Brush.
Rubyfluid Flux Soldering Paste
Safety Flux, Hobby Lobby
14180 - C.J.'S Flux Remover Gallon
Beginning Stained Glass – Foil Method
How do I remove flux after soldering the PCB board?
Horse Hair Tin Handle Acid Brush5.5 HandleThese Acid Brushes are designed for use when applying soldering flux / acid to sheet metal such as
Acid Brush for Soldering
Stained Glass Solder, Soldering Tools & Soldering Chemicals — Happy Glass Art Supply
Beginner's Guide to Stained Glass — KinderArt
Nokorode Paste Flux. Formulated for Stained Glass, Copper Foil or Came. Lead Free Metals, Wire & Decorative Soldering.
Clarity Stained Glass Finishing Compound – Stained Glass Stuff
A Couple of Words About Acid Brushes