Hello all -
I am a hobbyist who has been subscribed to the list for about a year.
I have learned many useful things here and I greatly appreciate the
service that all of you provide by sharing through Orchid.
Recently a problem has developed that I hope you may be able to help
me with. I have begun getting pits in sterling silver that I have
coated with Prips flux. I am using using acetylene + air to solder (a
prest-o-lite). I use Prips flux as an anti-oxident and use Battens
flux at the joints. The pits do not develop in the joints, but rather
on the exposed surfaces of the sterling. I was pickling in pH down,
but switched back to Sparex in case that was the problem. It was not.
I also stopped cleaning my metal with steel wool and switched to a
nylon pad in case that was the problem. It was not.
I mixed up a large batch of Prips flux about a year and a half ago.
I used Peter Rowe’s formulation (1qt water, 120gm Boric acid, 80gm
trisodium phosphate, 80gm borax) and stored it in a glass chemical
bottle with a bakelite lid. The flux was stored, in my shop, at
between 65 and 68 degrees F. Over time, solids have precipitated out
of the solution and have come to encrust the bottom of the bottle.
I have tried several dispensers and the most dependable one I have
found formerly housed “Revitalique daily protectant,” which is a hair
care product containsing collagen, protein and sunscreens. The bottle
was thoroughly washed before the flux was added. The plastic of the
bottle is labelled #1 - PETE.
Initially, there was no problem in using the Prips flux. The pitting
has developed only in the last month or so which is why I thought it
might be due to my switching from sparex to pH down. Unfortunately, I
am at a loss to isolate the problem. I am, however, assuming that the
precipitation removes all components of the flux equally; producing a
weaker, but still equally-proportioned (3:2:2) flux. A recent post
suggesting that the order of applying borax and boric acid separately
could matter has prompted me to wonder if the precipitation has changed
the proportions of the flux. Anyway, as there are many variables here,
I am asking someone wiser than I to direct my search for a cause.
Finally, when I use the prips flux, I apply a light but even coat of
liquid and gently heat the metal until the water evaporates leaving a
white coat over the surface. Under heat, the prips becomes clear and
then red (?). Is this correct? It seems to me that it used to turn a
sort of brown color. Finally, the areas with the pits are often
associated with a greyish, glassy buildup of the flux.
I am sorry this is so long, but I’m not sure what is
really important. I look forward to hearing your advice.
Cheers & thanks Debby Hoffmaster in sunny 70 degree Michigan