US Coins

Preserving Collectibles: Plan for collection recovery ASAP

Whether a disaster is a flood, tornado or fire, any material that survives will likely be wet. When recovering from a disaster, time is of the essence. As soon as waters retreat and the site is declared safe, the cleanup should begin.

Consider your personal safety along with your collection’s. Flood-damaged collections can be dirty, even contaminated with sewage — both human and animal — and other toxic substances. Before you start cleanup, try to determine how clean the water was. Err on the side of caution by wearing gloves and other protective clothing, and practice good hygiene.

Starting cleanup

Coins should be washed to remove any silt or deposits. Use a dilute solution of clean water (ideally distilled or deionized) and a mild detergent such as Orvus WA Paste or dishwashing liquid. Rinse in clean water. Dry the coins carefully with a clean soft cloth and rehouse in clean, dry, archival-quality holders. Return coins to as dry an environment as possible.

Paper notes are more problematic than coins. If the notes have been sitting in dirty water, you may wish to carefully submerge them in a tub of clean water before proceeding with drying. Handle wet notes carefully. Wet paper is usually weaker than dry paper.

If the notes are merely wet, they can be dried by placing them between acid-free paper blotters or paper towels. Reemay, a spunbonded polyester fabric, should be interleaved between the notes and the blotting paper to prevent notes from sticking to blotters. Reemay also provides good support for wet notes. Reemay and acid-free blotters are available at any archival supply house.

Replace blotters as soon as they become damp. If not too dirty, blotters can be reused when dried.

Fans increase the air circulation within a room to speed the drying process and help prevent mold growth, but ensure that blotting paper is weighted down with light weights to prevent blowing the notes around.

If you are unable to dry material right away, buy some time by freezing the wet material until you can deal with it.

Consider freeze-drying

Vacuum freeze-drying, used regularly by conservators to dry wet books, is a quick, effective means to dry wet paper.

The method is based on sublimation, a process whereby ice crystals vaporize without going through a liquid state. Water in its liquid state causes paper to swell and distort. Avoiding the liquid state during drying prevents this distortion from happening. Freeze-drying under a vacuum is quicker and more efficient than simply freeze-drying. Material to be vacuum freeze-dried should be frozen immediately and kept that way until it is treated.

To freeze, wrap your notes in freezer paper and place in a chest freezer. Vacuum freeze-drying is not a “do it yourself” activity — you must go to a company specializing in this technique. Your local library should have the names of companies in your area that offer vacuum freeze-drying.

Please do not consider using vacuum thermal-drying. Unlike vacuum freeze-drying, this technique uses heat, and the material stays wet throughout the whole process. The heat used in this technique can accelerate degradation and cause paper to become brittle, and because the water stays in a liquid state throughout the process, the paper can also distort considerably.

Collectors should consider developing a disaster plan, in advance of a disaster, to make recovery of their collections easier.

Susan L. Maltby, Toronto, is a private conservation consultant, with an interest in numismatic preservation.

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