Copper and brass
Tarnish is the metal reacting with its surroundings, not dirt on top of it. Every polish that removes it removes metal too.
Precautions
- Test on an inconspicuous area first
In detail
Copper and its alloys darken because the surface reacts with air, moisture and handling, and the patina is part of the metal rather than a deposit on it. There is no way to remove tarnish without removing metal, so polishing is subtractive and cumulative. The federal conservation procedure is correspondingly cautious, stating that copper alloy objects should usually not be polished at all, that where it is necessary the least abrasive approach is used, and that metal tools and commercial cleaners are excluded. It draws a distinction worth carrying into a kitchen: damage, including to the patina, cannot be addressed by cleaning — a corrosion mark or a scratch will not respond to more polishing, and continuing is how detail is lost. It also says these objects are not to be submerged and that liquid must not penetrate rims, edges or hollow parts such as handles — a real consideration for a pan with a rolled rim. A manufacturer adds the mechanical half: copper and bronze are durable but soft, and susceptible to denting and scratching. None of this says a domestic pan must be left dark. It says shine is spent metal, and the choice is worth making deliberately rather than monthly.
Properties
Sensitivity
- Acids
- Not known
- Alkalis
- Not known
- Chlorine bleach
- Not known
- Heat
- Not known
- Abrasion
- Recorded
- Porous
- Not applicable
“Not known” means CleaningHQ has not established this, not that the material is unaffected.
Related
- Copper and brass is commonly affected by Tarnish
Hacks and claims involving this
Sources for this page
Sources
Technical Procedures: Cleaning of Copper Alloy Objects
United States General Services Administration (GSA), Historic Preservation · Reference work
Relied on for: That copper alloy objects should usually not be polished, that where necessary the least abrasive approach is used, that metal tools and commercial cleaners are excluded, that objects are not submerged and liquid must not penetrate rims edges or hollow parts, and that damage including to the patina cannot be addressed by cleaning. (states this directly)
Verification: a person has read the passage relied on.
Read on — Section 2.02, cleaning of copper alloy objects, and 2.03, application of clear coat. Supports the claim as stated.
KALLISTA (Kohler Co.) · Manufacturer documentation
Relied on for: That copper and bronze are durable but soft metals susceptible to denting, scratching and scuffing, and that abrasive cleaners and solvents are not to be used. (states this directly)
Verification: a person has read the passage relied on.
Read on — The sections on nickel silver and chrome; brushed nickel, gunmetal and matte black; PVD finishes; acrylic, cast mineral and cast stone; acrylic baths with airjets; and cast-iron baths. Supports the claim as stated.
Last reviewed by a person on .