Cleaning Coins

It feels great to clean coins with things from around the house as its sort of ''free'' but often it really does not do the job, especially when the coin may be fragile, rare, etc. The choice of best cleaning agents depend on what environment the coin has come from and what the over-lying layer is made of. I can only speak from experience of coins from standard soil found in the United Kingdom which varies from sandy / peat / clay based. A specialist cleaning material based upon a 10% Sodium Hexametaphosphate / 90% good old water is superb for soaking and will dissolve / loosen most deposits in a matter of minutes. Clean bronze / silver pieces separately and take the coin / artifact out regularly to inspect removal of deposit and aid with soft bristle brush (old toothbrush).

Once most of the calcium based deposits have come off I like to let the coin dry. Bronze can also be brushed lightly with bristle brush and either dipped in molten micro crystalline wax or given light wipe with olive oil / petroleum jelly. This seals the surface to stop oxidation that is present (esp. ''bronze disease'' on bronze / copper coins) and enhances the surface patina color. If the surface details are very slight on any sort of coin (usually lowers value so no harm..) I rub with abrasive pencil eraser to lighten raised details to stand out from background. Silver coins can have final cleaning with clever trick (esp. good on medieval hammered coins from Europe)- take aluminum cooking foil, lay coin on flat piece of foil, spit (I kid you not!!) on coin and fold foil over to cover item. Hold coin gently between finger and thumb and wait until heat occur (chemical reaction with surface deposits) you may also notice smell of rotten eggs. Do not leave too long or coin could be damaged - a little at a time is always best when cleaning. Carefully wash and rub coin between finger and thumb and any legend details should stand out bright and shiny against a slighter darker background. I sometimes enhance the toning by adding of very small amount of black shoe polish / wax then rub off again.