Flux (from Latin "to flow
") is a substance that facilitates the flow of solder
by preventing the formation of oxide
s. Flux prevents oxides from forming by being more reactive
than the metal
s and solder that the flux is applied to. Generally flux is combined with water
to make a fluid that can be paint
ed or spray
ed onto the workpiece. When heat is applied the water evaporates to leave a glassy
coating. As oxygen and other elements combine with the flux it becomes less effective.
--Partially excerpted from The Complete Metalsmith
by Tim McCreight.