Request for information on a collectors' discussion list from one Geremy Gilbert:
My name is Geremy and im new to collecting old roman coins. It has been a complete blast so far. Does any one have any great tips on how to clean up old roman coins? Ive been soaking them in olive oil for a couple of months then taking a nylon brush and water to them. Im open for suggestions.
Reply helpfully offered by coin collector Bob Lilja:
You have quite a selection of methods, many engendering criticism. Electrolysis is popular, tumbling with various media is another, and there are assorted chemical treatments. Usually, patina and heavy cleaning are incompatible. Depends on how far you want to go.
The methods "engendering criticism" are the ones that destroy the artefact, making something which was already stripped of its potential information value by ripping it out of context (decontextualisation) into something also devoid of any information that may be contained in its original surface within the corrosion layers that formed on it when buried in archaeological contexts. In such a manner the destruction of evidence at the hands of the collector is total and irreversible. No surprises there, then.
To be fair, alongside Mr Lilja's scandalous recommendations, we have one from a Ken Baumheckel who puts the "dry coin under a low power stereo microscope and use a needle or a fiberglass scratch pen to remove obscuring material from the coin's legends and devices". This is far closer to what archaeological conservation specialists would do, though in the wrong hands such tools can also lead to damage (when does mechanical cleaning become "tooling"?). Mr Baumheckel forgets though to mention the safety precautions needed for using a "fibergalass scratch pen" (nasty tools) in such a manner and the necessity to stabilise the corrosion products remaining by use of inhibitors and/or controlled storage. Of course those who buy coins in bulk simply dunk them in something, "zap" them by electrolysis, or tumble them. They bought them "cheap" after all, and even if the majority are damaged by such treatment (and can be dirtied up a bit and sold on), some may come out to be identifiable, after a little "enhancement".
Posts like Mr Lilja's really do put the claims made by portable antiquity collectors that they are "saving and preserving pieces of the past for future generations" into perspective. Many of them are instead actively trashing the artefacts in their "tender, loving" care through ignorance, carelessness and haste.