To make it, mix 120 grams boric acid, 80 grams borax (you can get
borax cheaply in the grocery stores laundry aisle, sold as borateem or
the like. These are sold as detergents, but are almost all borax with
a bit of whitening agents. Those are the little blue crystals, which
don’t hurt the flux at all), and 80 grams TSP (be sure it’s the real
stuff, not a substitute. Must be trisodium phosphate, not some of the
phosphate free cleaners confusingly labled with similar names) into
about a liter of boiling water (tap water is usually fine). dissolve
all. May need a tad more water to keep in solution once cool.
To use, preheat the silver enough with a soft torch flame so that the
flux, when sprayed on with a sprayer, instantly dries on contact,
forming a uniform white crust on the silver. Don’t heat so much that
the silver discolors from the heat. Coat all sides. Put on just
enough so that the reflective surface of the metal is hidden, and all
you see is the flux coat, but not more than that or it can pull back
when you later go to solder, leaving unprotected areas. When you do
go to solder, as you heat it, the frosted surface crust should glaze
over as it melts, leaving a thin transparent coating that protects the
silver from the atmosphere even through fairly prolonged
soldering/heating cycles.
The best sprayers produce a fine uniform spray. Most trigger spray
bottles don’t do that, making it hard to apply, giving you too much in
some areas, not enough in others, or causing puddles, which then form
rings of thick flux with little in the middle when you heat it, and
then don’t glaze over properly, but pull away as you heat. My
favorite sprayers are the cheap little mouth atomizer sprayers sold in
ceramics supply shops for application of ceramics glazes. These are
just two tube mounted to a hinge, one dips in the flux, the other is
shorter and wider in diameter, and lets you blow across the end of
the first. Simple to make if you had to. Some types of perfume spray
bottles work too, as do some of the inhalent/atomizers used for nasal
sprays or asthma inhalers. So does a cheap style of air brush known
as an external mix air brush, which does the same thing as that mouth
atomizer only with a compressor or bottle air supply. Harbor freight
sells a cheap little chinese made one that works fine.
One the flux is applied, you then apply soldering flux. prips is not
a highly active flux, and won’t work especially well for soldering,
though if your joints are clean and tight, the solder clean, and your
technique good, it can work. Usually, though, one applies additional
soldering flux JUST TO THE JOINTS. soldering fluxes don’t protect from
fire scale as well, if at all, since they tend to burn out too
quickly. The white paste fluxes especially tend to do this. When I
do this, I usually apply the prips flux to the seperate pieces being
assembled, let them cool again, then gently set up the soldering
operation after they’re cooled. I use a liquid soldering flux
(batterns), and the liquid dissolves enough of the prips crust at the
joints to let the pieces contact enough other properly.
After soldering, the prips comes off in either hot water or faster,
in pickle. the metal may have a slightly dusty whiter appearance, but
when you go to polish, you won’t find that subsurface fire scale that
can be such a bane to polish off.
BillyBob
Made By Hand
Bill
Leesburg, Florida