I just attended the last session of the
ANS Lyceum on
Collection Management and Conservation. This session was by David
Hendin. I have communicated with him in the past on some specific bronze coins of mine that need cleaning and he was super nice and helpful. He gives a great presentation. From my notes, some items that people may find helpful and interesting. These notes all apply to bronze coins only. Some of these are pretty well known, others maybe not so much, some might be controversial.
1. Manual cleaning is always better than chemical. Chemical cleaning is a last resort.
2. He is fairly adamant that the
average person shouldn't try to clean coins as it is so difficult to do well and the potential for making a coin worse is high.
3. Never use olive oil or any oils. He is a distilled water guy.
4. He showed a photo of
his tools. This is what really interested me and surprised me. Not a scalpel in sight.
Tools are: binocular microscope 10x-30x; one soft bristle brush made with hair (very soft toothbrush also works); one whetstone for flattening needle points; one pencil with eraser; and four pin vises that hold various sizes of flattened needles, all very small needles. That is it.
5. For bronze disease, he uses 2-5% solution of Sodium Thiosulfate or 5% solution of Sodium Sesquicarbonate, either in distilled water. The
numiswiki article on one of these substances seems to track
Hendin's recommendations, although some other stuff in the article he wouldn't agree with, such as olive oil and
Ren Wax.
6. He does not like
Ren Wax. This somewhat surprised me because it is recommended a lot. I personally just don't like the look it creates, although I am sure I have a few coins where it was used. To me, it looks unnatural. I suspect
Hendin feels the same way. In any case, it confirmed I will never use it.
There was a lot more, this is what I remember best. I have some Phillip II bronzes and late
Roman coins that have been soaking in distilled water for ages. Time to get a couple pin vises (they are
cheap) and pins and get going.
His method is pretty slow, but he gets incredible results. He also discussed chemical cleaning and how difficult cleaning silver is. The pins will scratch a silver coin.
Virgil