Having a legacy to pass down is an important part of why people collect coins. If coins are stored wrong, and ultimately damaged, the value that one wished to have passed along may be lost forever.
Just like most collectibles, the surface of a coin is its most important aspect. Yes coins can have value for metal content, but the collectible value is largely based on the condition of the outer 'skin' of a coin. Just like a valuable painting if the surface is damaged the value may be gone. Taking care to preserve your coin's fragile surface is very important.
Many older holders (books, binders, rolls, and flips) have chemicals that can react with your coin's surface. Things such as sulfur, iron, and poly-vinyl-chloride contained in the materials or staples used to hold them together are common culprits to coin degradation.
Sulfur was common in older paper products. Books that were commonly used to store coins often have sulfur in them. With single window books (where only one side of the coin can be seen) there is a good chance that the side touching the paper is much darker than the side exposed to air. With two sided windows it is common to see the coin's edges turning colors from paper it touches. Paper flips, or coin sized envelopes, were also a very common storage choice for years. If your coins have been stored in these flips for years it is likely that they have toned due to the proximity of the paper.
As technology progressed plastics became popular for flips, pages, and see through books. What people did not know was that the PVC (poly-vinyl-chloride) in the plastic would precipitate onto the surface of the coin over years of storage. Coins that have been stored in PVC holders often feel slimy and sticky to the touch and obtain a greenish appearance from the chemicals left on the surface of the coin. If the PVC is left on the coin it can erode or 'eat' into the coin's metal.
Staples used to hold flips together are often made of ferrous metals that deteriorate by rusting. If the staple is close to the coin it is common to see toning near the edges where the staple was used. In moister climates it is common to even see actual rust making it all the way onto a coin.
Today there are a host of new options available to collectors. PVC-free flips, non-sulfur paper, and inert holders are now common in the market. If you have valuable coins in older holders it may be time to seek alternative storage for your coins.
Cleaning coins is usually not good for their value, but if you have coins that are being damaged from improper storage it may be a necessity. You can consult a professional coin dealer for advise. Most coin dealers will not clean a coin for you because they do not want to be liable if the coin is damaged. But, there is a professional coin preservation company available for those valuable coins that do need preservation. Numismatic Conservation Services is located in Florida, but does have authorized dealers around the country that can assist you in getting your coins to the company.
If you have valuable coins that have been stored for years it might be wise to re-assess how they are being stored. You may find it necessary to update your storage method or even to have them conserved to preserve their value. Remember to consult a professional before either cleaning or having your coins cleaned, it may be the way to make sure your legacy is preserved.
• Allen Rowe is the owner of Northern Nevada Coin in Carson City.