I have a little "kit" from Alpha Metals that I got years ago (and sadly, I don't think they're available any more). It has a roll of silver-braze wire and a tube of flux. Originally, the flux was creamy, but over time it's gotten so stiff that I can't squeeze it out of the tube, plus, it seems to have grown some crystals that make it hard to work with.
The flux contains potassium fluoride and potassium fluoroborate; is there some way to "rejuvenate" it? I tried mixing some with a bit of water, but that didn't seem to work so well.
Alternately, is there another easy-to-get flux I could use? I only rarely need to silver-braze anything, so I don't need/want a gallon jug of something...