I like to try to make things from scratch, at least once or twice, and so made myself some solder, aiming for Hard and Eutectic.
I am filing some down to use as powdered solder, and was curious about adding boric acid, or borax, or both, directly to the powder.
I remember reading Victroria Langford’s site, hers does contain the flux and for paste, she advises to just use some water. Something similar, though, i’m really not looking to get anyone’s trade secrets. It’s the sort of experimental learning.
The other wonder i had, i read somewhere a blurb that just said to use Zinc Oxide if you intend to powder your solder; what if you made a Eutectic alloy, then instead of pre-preparing various hardnesses, you added a touch of powdered zinc or zinc oxide as you worked? I imagine the idea was to prevent the Zinc from burning off, as zinc oxide has a much higher vaporization temp. What i don’t know, is if the intent is to reduce the oxide to a metallic state IN the melt, or just disperse it in the melt without actually alloying it. And in that case, would it even matter if it was in the alloy itself.