Green oxide after immersion in pickle solution

[mdk]

Hello everyone,
I dipped an 800 silver ring in boiling in a solution of vinegar and salt in order to remove the black oxide resulting from the melting of the metal, after I pulled it out and rinsed it off, the oxide was gone. Once dried and placed on the work surface, after a few hours some green copper oxide began to form. I thought it might be due to the penetration of the vinegar into the pores of the metal and the consequent release of copper acetate. Do you have any advice? Thank you.

[Dennis]

Yes, you are right. The green colour would be due to base metal salts, particularly of copper. This can be avoided by boiling up in a weak alkaline solution after pickling, followed by plain water.
Common alkalis to use would be bicarbonate of soda (baking soda), or more cheaply, soda crystals. Dennis.

[mdk]

Yes, you are right. The green colour would be due to base metal salts, particularly of copper. This can be avoided by boiling up in a weak alkaline solution after pickling, followed by plain water.
Common alkalis to use would be bicarbonate of soda (baking soda), or more cheaply, soda crystals. Dennis.

I tried with baking soda by boiling them in a small metal container but I didn't get any results, maybe with caustic soda it is different being a very powerful base. Now I have mounted the stone on the ring, is there a possibility that at some point the residual vinegar contained in the pores by dint of making a chemical reaction with the air will run out and stop producing green oxide forever?

[CJ57]

Washing soda isn’t caustic soda. You can buy soda crystals in any detergent aisle in a supermarket or local shop

[Dennis]

You are of course unusual in using 800 silver. Casting it makes some micro-porosity inevitable, so it will be more prone to retaining pickle. The higher base metal content makes it more prone to corrosion.

Having hopefully converted any lingering acid into soluble sodium salts and thoroughly washed them away, there is every chance that you will be rid of the problem.

That said, it is hard to quantify 'enough', so only time will tell. Dennis.