Where tarnish actually comes from
Usually the box, not the air. Wool, felt and foam rubber give off sulphur, so the lining that protects a piece is often what dulls it.
In detail
Tarnish is a chemical reaction and conservation guidance names the reactant: sulphur compounds are probably the strongest tarnishing agents. It reaches metal from burning fossil fuels — so urban and coastal air are the worst outdoor cases — and, far more usefully for a household, it is GENERATED BY ORDINARY MATERIALS: foam rubber, carpet padding, paints, wool and felt. That explains something people find baffling: a piece worn daily often stays brighter than one shut away, because the drawer was lined with felt, or the piece wrapped in wool. The protection was the problem. It also explains two odd handling rules. Synthetic rubber gloves are not recommended for silver or copper, because some contain high proportions of sulphur and chlorides. Cotton gloves with PVC nubs are excluded because the residue may cause tarnish. In both cases the thing meant to keep skin off the metal is itself the contaminant. The practical conclusion is that storage does more than cleaning — which matters, because cleaning a tarnished piece removes metal and storing it better costs nothing. Untreated cotton or acid-free tissue in a closed container, away from wool, felt and rubber.
Why
- Jewellery is explained by Where tarnish actually comes from
Sources for this page
Sources
Museum Handbook Part I, Appendix O: Curatorial Care of Metal Objects
National Park Service, US Department of the Interior, 2002 · Reference work
Relied on for: That sulfur compounds are probably the strongest tarnishing agents, that sulfur is present in air from burning fossil fuels and is generated from foam rubber, carpet padding, paints, wool and felt, that synthetic rubber gloves are not recommended for silver or copper because some contain high proportions of sulfur and chlorides, and that PVC nubs may cause tarnish. (states this directly)
Verification: a person has read the passage relied on.
Read on — Sections on metals and alloys, surface treatments, identification, corrosion, atmospheric pollution, cleaning and deterioration, handling, and protective coatings. Supports a wider statement — our claim was widened. Gives the register gold and gold plating without a single retailer claim, and supplies two facts no consumer source carries: that wool and felt are tarnishing environments, and that a jeweller's cloth works by weave stiffness rather than by abrasive. It also independently confirms the polishing-removes-metal mechanism this catalogue has carried since Sprint 12.
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