Reply To: cleaning museum silver – sodium carbonate or calcium carbonate?

Marianne Weldon

Calcium Carbonate is inert. If you leave some behind, it might not look good (chalky and white), but it will not react with the surface in a detrimental way.

The silver dips commercially available are quicker, but often leave tarnish inhibitors such as mercaptans behind. If the actual polish is left behind it can promote corrosion, particularly stress corrosion cracking.

While it is much more labor intensive, I do believe that using precipitated calcium carbonate (the shape of the precipitated calcium carbonate is less rough and therefore better) is the preferred approach for museum collections.