14kt, 20kt gold & liver of sulfur gel

Please help if you can;
I have used liver of sulfur for years to blacken my sterling silver or indian (pave diamond) silver & 14kt or 20kt solid gold pieces. With in the past 14 months the gold now reacts to the LOS gel. The gold ends up looking tarnished in an ugly reddish way. I have tried EVERYTHING I can think of to avoid having the gold react but with no luck. I’m looking for assistance on how to ONLY have the silver react and not the gold (with out applying a resist to the gold). (I have tried new los bottles, old los bottles, bottled water, heated water, cold water, fresh pickle, using copper tongs, wooden tongs, new containers to mix solution)
Thank you in advance!!

Hi Tracy,
I’d call the gold suppliers or casting house, there have been new alloys produced that, while casting easier, resist certain solders, and , as I have found, oxides.
Some are designed with that purpose in mind .
Just thinkin’