Select a flux. Very like the solder, the flux needs to be specialized for aluminum or for The mix of metals you intend to affix. The best selection is to get the flux with the same source as your solder, as They're probable meant to get the job done jointly. https://zionrfoxi.blogofoto.com/58394253/rumored-buzz-on-types-of-solder-to-use-on-aluminum-radiator