where I may have gone wrong?!?
Just add more water.
Prips (which is spelled with ONE “P” at the end, not two. It’s named
after the late John Prip, who introduced it to U.S. silversmiths) is
a mix of 3 parts boric acid to 2 parts each, borax and sodium
phosphate. Dissoved in enough water to keep in dissolved. If you’re
getting lumps crystalizing back out as it cools, just add enough
water to redissolve it. Tap water is fine.
Notes:
I’d normally start with quantities of 96 grams of boric acid, and 64
grams of both the others to a quart of water. Sometimes it needs
little more water if I’m not so careful weighing the stuff. There’s
no harm in making it more dilute. Much more dilute if you like. It
just means you have to spray more flux on to get a good coat on the
metal.
It DOES have to be sprayed for best results. You can sort of use a
brush, but this doesn’t work so well. The best sprayer I’ve found is
a mouth blown atomizer intended for ceramics glazes. It’s simply two
tubes and a hinge. Simple, and doesn’t clog the way many trigger
sprayers will do.
It’s critical to make sure that the sodium phosphate you use
actually IS sodium phosphate. You can actually find three forms of
this. Theres monosodium phosphate, disodium phosphate, and trisodium
phosphate, commonly referred to as “TSP”. The last is the most
commonly used and found, and usually cheapest. But all three will
work. The problem arises in that TSP, which has long been used as a
fairly strong alkaline cleaning agent, being a phosphate, presents
pollution problems in waste water streams. So at least in the U.S.,
many locations have banned or discouraged it’s routine sale. Sold
instead, are sodium silicate based cleaners, or other cleaning
agents, which often are labeled with confusingly similar names, since
they’re marketed for the same “pre-painting, wall washing” sorts of
tasks TSP used to be recommended for. The trick is to make sure
you’ve actually got TSP, not some other chemical, since those others
won’t work.
However, at least in the U.S., you can use “Cascade”, a common brand
of dishwashing machine powdered detergent. This stuff too is made in
phosphate free formulas in some places, and these don’t work. But the
green box version which lists a phosphate content, DOES work in place
of plain TSP, with the formula to mix it otherwise the same. This
alternative chemical was suggested by Fred Fenster, so the flux gets
then called “Frips”. I don’t know if this is available in the UK, but
if you’re moved to do so, you could always research similar products
sold there…
Peter Rowe