Aluminium foil and bicarbonate of soda to clean silver

Does it work?

Disputed

The hack's own claim - that it removes tarnish - is true. What is in question is whether it should be used at all: two conservation authorities say no to the class it belongs to, while the domestic version specifically has been tested by nobody.

This is a verdict on whether the technique is effective. Whether it is safe on a particular surface is a separate question, answered below.

Where not to use it

Why it works

The claimed mechanism is correct as chemistry. Aluminium is more readily oxidised than silver, so in a hot electrolyte with the two metals in contact the aluminium gives up electrons, the silver sulphide is reduced back to silver, and the sulphur leaves with the aluminium. The bicarbonate provides the ions that let the cell work. What the claim leaves out is what the reaction does to the SURFACE rather than to the tarnish. The conservation objection to electrochemical cleaning is that it deposits metal on top of the original surface, obscuring the finish permanently, and the reduced silver does not return to where it came from. On a plated object the same reaction reaches a plating that is only microns thick.

Background

This hack is unusual: it is not folklore. Lining a bowl with aluminium foil, adding bicarbonate of soda and hot water and letting the silver touch the foil sets up a galvanic cell, and the tarnish visibly clears. The mechanism works. That is exactly why the conservation position matters. Both conservation bodies rule the technique class out, and the UK professional body states it flatly: NEVER USE ELECTROCHEMICAL CLEANERS, because they deposit a layer of another metal on top of the original surface and the original finish is then irretrievably lost. The museum sheet says the same in the same words. One honest limitation belongs up front. Neither source names the domestic foil-and-bicarbonate version; both address electrochemical cleaning as a class. Placing the kitchen method inside that class is an inference rather than something a conservator wrote. What is not in doubt is the comparison the hack is usually sold on. It is offered as gentler than polishing, and polishing genuinely does remove silver every time.

What it does not do

• Both conservation bodies rule out electrochemical cleaners as a class, one of them saying never
• Neither source names the domestic foil-and-bicarbonate version; placing it in that class is an inference
• The stated objection is that the original surface finish is irretrievably lost, which no later cleaning restores
• On silver plate the coating is microns thick, so there is very little to lose before base metal shows
• It does nothing about what causes tarnish, which is mostly storage, handling and sulphur sources

What to use instead

• Sterling silver — 92.5% silver, and a rare material where the standard domestic treatment permanently removes some of the object. Tarnish contains silver, so cleaning it off costs silver.
• Silver plate — A microns-thin layer of silver over a base metal. Everything that cleans sterling also thins the plating, and once it is through there is nothing underneath to polish.
• Microfibre cloth — Split synthetic fibres with a very large surface area, which lift and trap soil mechanically — often with water alone.