Storing Your Coins
A relatively constant, moderate temperature and low humidity are preferable for long term storage of numismatic collectibles. Placing packets of silica gel in coin storage areas helps control atmospheric moisture.
Several types of storage holders for coins are available. Most anything will do for coins with little numismatic value, while nearly airtight holders made of inert materials are a good idea for valuable coins.
* Bags, jars, and boxes are adequate for pocket change and circulated bullion coins.
* Paper envelopes of various sizes are sometimes used for one or more coins. Be sure to use envelopes made explicitly for holding coins, or your coins may change color (tone) over time due to reaction with sulfur or other chemicals present in the paper.
* Various brands of folders and albums are sold for series and type sets. When properly used, they offer some protection from wear and handling. Over several years coins may tone due to reaction with sulfur or other chemicals present, and they are therefore not a good choice for long term storage of higher grade coins.
* Plastic flips are available in various materials. "Soft" flips are made from polyvinyl chloride (PVC) which decomposes over time with disastrous results for coins. They are therefore not suitable for long term storage. Mylar and acetate flips do not contain PVC. However, they are hard (may scratch the coin if not inserted and removed carefully) and brittle. While not airtight, they are reasonable choices for moderate value coins that will be "left alone" for multiple years but less so for coins to be shipped or that will be removed and reinserted.
* Mylar-lined cardboard, often called "2x2s" but also available in other sizes, are similar to plastic flips. A coin is placed between the two halves, which are then stapled together (some brands contain an adhesive).
* Tubes are plastic containers designed to hold a number of the same size coins. They are fine for bulk storage of circulated coins and can be used for higher grade coins, provided the coins do not move. A disadvantage is that the coins cannot be viewed without being removed from the tube.
* Hard plastic holders are preferable for more valuable coins. They are not known to contain any materials that harm coins and offer good protection against scratches and other physical damage. They are available for individual and small sets of coins.
* Slabs are sonically sealed hard plastic holders for individual coins. They offer good (though still not perfect) protection. Because of the expense of having a coin slabbed, they are generally suitable only for more valuable coins.