raimundo wrote:dont buy the fancy jewelers flux, its for gold and silver only, just use the white paste flux, that will work on base metals.
What I was given is "non-fluoride silver solder flux", "Low temp flux [for] brazing and silver soldering ferrous and non-ferous metals" - Dandix brand.
It has a weird foamy consistency. Funny that "low temp" is above 1200 degrees F here.
I did mention that I was working with brass, and indeed it does its job just fine.