I am aware of argentium but have been warned against it and would love continuum but it costs too much and so I would like to keep this post about standard, silver/copper sterling.
With that said, I have been looking for a solution to the issue of firestain and after some research I gather than it comes down to flux and not overheating your piece. However which flux I cannot tell. Prips flux seems to be very popular amongst orchidians as is cupronil, which however does a better job stopping firestain as a firecoat? Most say firescale has been nearly or entirely eliminated with a generous coat of prips flux. Does commercial or homemade prips flux differ in composition or effect?
I would also like to know about simple boric acid and alcohol as a firecoat. I assume better than nothing but not nearly as effective as prips or cupronil?
Does heating to hard soldering temperatures (around 750-780 Celsius) enough to be considered “overheating your metal” and causing firestain?