Preserving Currency

Dear Donia,
What's the best way to preserve paper currency and coins?

Q. Dear Donia,

My mother has British paper currency and coins from 50+ years ago. It's the currency that was used before the current pounds and coins were introduced, so some of them are very old. She has it displayed in a glass box. Is there a better way to preserve it?

A. A. Dear Sheri,

What a great collection to have.  Ideally, they would not be displayed, but stored safely in a box in the dark. However, that defeats the purpose. So, what can we do to keep these materials on display?

The coins are the most stable. If any of them are silver and showing tarnishing, however, you will want to look at what the frame of the box is made of and what materials are used in the base. Wood off-gases volatile organic compounds that can speed up corrosion so if the frame of the glass box is wood, you will want to seal it with a water-based polyurethane to slow the release of the chemicals.  

Currency is made from high-quality rags and is very stable in and of itself, we just want to be sure we keep it that way.  Paper objects are generally the more fragile as they can be impacted by acids from the wood, acidic base materials, as well as from light and high temperatures and relative humidity.  You will want to be sure that the base material (what the paper and coins sit on) is a stable material, such as cotton muslin or a rag-based mat board.  You will also want to be sure that the glass box is not in line with any direct sunlight as that can lead to fading and deterioration of the paper, even the best kind.  Also, keeping the temperature and relative humidity at levels that you are comfortable, will be best for the currency.  Finally, if it is possible to replace the glass in the case, you would want to change out the glass for glass or Plexiglas that block ultraviolet radiation. UV blocking glass or Plexiglas act as sunscreen for the materials in the case.  UV blocking glass is most commonly found under the brand name of TruVue (as for it at your local framers) and UV blocking Plexi under the brand name Lexan.

I hope this helps, but if you have any further questions, just send them to "Dear Donia"!