Jessee,
The carrier of the chemicals in Cupronil and Prips is water. Water
based fluxes puddle when sprayed on cool metal. The anti-firescale
coating of the metal is produced when the metal is heated to a
temperature above the boiling point of water (around 212 degrees).
This causes the water carrier to boil off as the flux hits the
metal. This leaves a coating on the metal of the anti-firescale
chemicals. The silver should not oxidize at this low temperature.
The metal should not be overheated. Practice with a torch and you
will develop the technique that allows you to put on a consistent
chemical coating on the metal.
Lee Epperson