Choose a flux. Very like the solder, the flux should be specialized for aluminum or for the combination of metals you plan to affix. The simplest solution is to get the flux in the exact resource as your solder, as These are very likely intended to do the job jointly. https://buyspoilerforcar04527.blogsumer.com/27020511/the-5-second-trick-for-types-of-solder-to-use-on-aluminum-radiator