Casting of silver causes a fire scale to form on the silver because of the high heat and exposure to air. When a silver piece is released fresh out of the investment material, it is very dark and scally. The first step is to wash and scrub off all the investment, then to drop the piece into the pickle bath.
I use an organic acid solution that it heated to slightly steaming temperature in a small crock pot. This is the pickle. The piece, depending on solution temperature, may stay there for about a half hour or so.
I usually am able to scrub off the blackness about half way through, then a bit more time in the pickle the silver will be the snow white as seen here.
This is actually the pure color of silver before it is polished. The slight pink seen on the metal is a blush of the copper that the acid draws out. Sterling is 7.5% copper to make it hard and more durable than pure silver.
After this stage, the sprue is cut off and filed smooth untill evidence of the sprue location no longer exists. Then comes all the polishing and burnishing to the final finish.
Some pieces have an applied chemical darkening to add contrast.
So after this point is where all the working with silver really begins. I love it!