I was told by the tech at Hereaus that a heated 50% solution of phosphoric
acid is the ideal pickle.
Forgive me if I am wrong but doesnt that sound along the lines of a heated
(concentrated) Coke or Pepsi solution?
Indeed you are correct, in fact, I've considered boiling up some Coke and
trying it... :) Unfortunately, the phosphoric acid in Coke is too weak.
The thinking behind the phosphoric acid pickle is in regard to the now
common bright cast gold alloys. Apparently, sodium bisulphate pickles can
etch the silicon and enter into the grain of the metal weakening it, or so
I have been told. The phosphoric acid pickle also leaves silver pure white,
that is, it removes the black and gray fire scale that Sparex frequently
seems to leave.