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Basic Care of Coins, Medals and Medallic Art
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Basic Care of Coins, Medals and Medallic Art
Introduction
Coins, medals, and medallic artEndnote1 are commonly found in museum collections. These items often have considerable curatorial and monetary value. Mishandling, inappropriate storage materials, or an inhospitable storage or exhibit environment can cause irreparable damage and loss of value. This Note gives general guidelines for preserving these items.Get more news about Metal Medal,you can vist our website!Handling
Coins, medals, and medallic art should be handled by their edges. As with all metal objects, the handler should wear clean, well-fitting cotton or plastic gloves to protect the metal surface from the skin's corrosive oils and acids. This is particularly important with proof coins that have a mirror-like finish. Any mark, however small, can disfigure the coin and lessen its value. Handlers who find gloves uncomfortable may wish to consider wearing finger cots, which are small latex sheaths designed to fit over individual fingertips.Note that cotton gloves must be used when handling silver coins, because the sulphur in latex causes silver to tarnish.
Display and Storage
Environment
The ideal environmental conditions for displaying and storing coins, medals, and medallic art are the same as for other metal objects (consult CCI Notes 9/2 Storage of Metals). Relative humidity (RH) should be kept as low as possible because metals become increasingly susceptible to corrosion as the humidity rises. Ideally, the RH should be below 30%; however, this is often impractical with mixed collections, where levels of 35–55% are the norm. In these cases, regular examination and condition assessment will indicate whether or not the storage or exhibit environment is appropriate. If the collection begins to corrode, a separate dry microclimate should be established using silica gel (Lafontaine 1984 ; Raphael 1992 ).Although coins and medallic art are not sensitive to light, the ribbons that usually accompany military or commemorative medals are. The ribbons, often silk, are highly susceptible to fading. Medals with ribbons should be stored in the dark and their exposure to light should be limited. Exhibit light levels should not exceed 50 lux and 75 µW/lumen (consult CCI Notes 2/1 Ultraviolet Filters and 2/4 Environmental Monitoring Equipment (retired)).
Storage Holders
All coins, medals, and medallic art should be stored individually in protective storage holders. Choosing an appropriate storage holder is important. The holder should provide long-term protection and not cause any physical or chemical harm.Traditionally, plastic flips and paper envelopes have been used for housing these collections. Flips have two pockets: one for the coin and one for curatorial information. Paper envelopes should be made of good-quality, acid-free rag paper.
Of the two types of holders, the clear plastic flips are preferable because they reduce handling, i.e. they allow the coin to be examined without removing it from its holder. Plastic holders should be made from an inert, pure, archival-quality plastic such as polyethylene, polypropylene, poly(ethylene terephthalate) (e.g. Mylar D, Kodar), polystyrene, or poly(methyl methacrylate) (e.g. Plexiglas).