IN A NUTSHELL: With coin holders, it's largely, "To each, his own." But each type of coin holder has its advantages and disadvantages. And you should quickly remove any coin you buy that's in a soft vinyl flip to avoid causing damage to it.
We buy coins to look at them, and the coin holders through which we look can greatly affect our viewing pleasure. It's common knowledge that there's no such thing as the perfect coin holder, but that's never stopped coin collectors from searching the best coin holder for them.
Much about coin holders is subjective. My preferences regarding the best coin holder may be different from yours. What follows resulted from talking with coin collectors, coin supply dealers, coin holder wholesalers, and coin holder manufacturers, as well as my own experiences in testing out or using each of these holder types.
Your choices in coin holders include but aren't limited to the following, in order of estimated popularity:
These holders consist of white cardboard with a clear Mylar pocket to let you view the coin. You can attribute and describe coins on the cardboard with pen or pencil. These holders are called 2x2s because the holder's dimensions measure 2 inches by 2 inches, though most coin holders are this size as well. (In Europe larger and smaller sizes are used more commonly than they are in the U.S.)
One problem with 2x2s is that paper dust from the cardboard can cause spotting over time. Some holders, however, advertise that they're dust free. The staples on the staple-type holders can potentially scratch a coin if you're not careful when removing it or rust and leach chemicals onto coins. The adhesive on self-sealing 2x2s can potentially damage coins over time, and the adhesive can wear out as well, causing the holder to pop open.
2x2s are somewhat chintzy looking, but they're inexpensive, relatively safe, and popular. They're often used by coin dealers because of their low cost and because it's easy to write on them.
With these all-plastic two-part holders, you flip up the part of the holder holding the coin to view the coin's reverse. You can choose flips with one pocket (for the coin) or two pockets (one for the coin and the other for a paper insert on which you can attribute and describe coin, optionally using a computer). Unlike many other holders, safety flips let you view edge of the coin. They're called "safety flips" because they're relatively safe for long-term coin storage.
There are two kinds of safety flips, generic safety flips and Kointain Saflips. Generic safety flips are made from low-plasticizer PVC. They're often mistakenly called non-PVC flips, PVC-free flips, or unplasticized flips despite the fact that they do contain PVC, which is an abbreviation for the plastic with the name polyvinylchloride (or vinyl for short).
Generic safety flips are much safer than ordinary PVC flips for long-term coin storage because of their low levels of plasticizers (most typically, phthalate esters). It's primarily the plasticizers used to soften the PVC, not the PVC itself, that can damage a coin's surfaces over time.
Generic safety flips aren't perfect. Their hard edges may scratch a coin when you insert or remove it if you're not careful. They may crack with repeated opening and closing, forcing you to replace the holder. They may turn pale color over time, also forcing you to replace them.
Generic safety flips shouldn't be used with proof coins because the PVC itself can degrade over time, releasing small quantities of gaseous chemicals, including chloroacetaldehyde, hydrochloric acid, chloroethylene epoxide, formaldehyde, formyl chloride, formic acid, and carbon monoxide. These chemicals, in turn, can cause microscopic pitting on coins, leading to hazing on a proof surface. This outgassing occurs more if the holders are exposed to excessive humidity or sunlight.
There are several different kinds of generic safety flips. The Super Safe brand (sometimes called Madison coin flips since they're made by Frame-A-Coin of Madison, N.J.) are available at many coin shows and through Brent-Krueger Coin Supplies. They come in sheets -- you tear off the individual flips.
Other generic safety flips are made by International Plastics of Altadena, Calif., and are available from Jake's Marketplace. They're thicker and sturdier than the Super Safe flips (and they consequently make nice mini-coin stands), but they crack more easily and are thus not as practical for large coins.
Still other generic safety flips are made by various manufacturers in China, including those sold by Brooklyn Gallery Coins & Stamps.
Generic safety flips are attractive, relatively inexpensive, and popular. To reduce the chances of generic safety flips causing problems in coins over long periods of time, you should store coins in them away from excessive heat (less than 85 degrees F.) and humidity.
The other main type of safety flip is the Kointain Saflip. These flips are made from Mylar, which is one brand name for the plastic with the name polyethylene terephthalate. Mylar is thought to be somewhat safer over the long term than low-plasticizer vinyl. It's also not as prone to cracking.
One negative of Kointain Saflips are their horizontal striations, which are unsightly and can interfere with viewing of the coin inside. These flips also have sharp corners. Kointain Saflips are more expensive than generic safety flips but can be a good choice for proof coins and otherwise when safety is paramount.
Flips, also called soft vinyl flips or PVC flips, are commonly used by dealers to sell coins and by some grading services when people submit coins to them because they make it easy and safe to insert and remove coins from them and because they're inexpensive. However, regular flips are unsafe for long-term coin storage.
Flips consist of PVC (polyvinylchloride, also known as vinyl), stabilizers (to prolong life), and plasticizers (to soften the plastic). Plasticizers mixed with the PCV can damage coins over time, causing "PVC damage," which looks like green goo. Damage occurs faster when flips are exposed to excessive heat, humidity, or sunlight. Early PVC damage can be removed with acetone. More severe PVC damage can corrode a coin's surfaces, causing permanent damage.
If you buy a coin in a soft vinyl flip, you should remove it and place it in another storage medium. One rule of thumb is that no coin should sit in a soft flip for more than six months.
Air-Tite holders are the most attractive coin holders next to slabs, and depending on your views about slabs, you may find them more attractive. You can choose various color combinations to best highlight your coins, whether copper, nickel, silver, gold, or other metal.
The Air-Tite system consists of a snap-together acrylic inner holder that fits snugly around the coin; a polyethylene white or black ring that fits around the inner holder; a black-, blue-, burgundy-, red-, or green-colored velour-covered cardboard display card into which fits the holder and ring; and a black polystyrene frame holder with a wood finish and stamped with gold- or silver-colored lettering.
You can optionally use a host of other accessories, including storage boxes, display easels, albums, display boxes, wall frames, and presentation cases.
The Air-Tite system is relatively safe for long-term storage. The size is nonstandard, with the 2-3/4 inch by 2-3/4 inch display cards being larger than the 2 inch by 2 inch size of most other holders. Air-Tites are considerably more expensive than most other holders, but they may be worth it.
Intercept Shield holders
These relatively new holders are made with a material that's designed to intercept and neutralize sulfur and other contaminants and thus prevent toning. This can be beneficial or not. Many people regard nicely toned silver coins as the ultimate in eye appeal. On the other hand, coins that have toned unattractively just look tarnished or stained, and brown copper coins are generally less attractive and worth less than red ones.
Intercept Shield holders measuring 2 inches by 2 inches are made for different sized coins as well as for coins that are already in slabs. You can also buy different sized Intercept Shield boxes and albums. You can optionally use the Intercept Shield boxes with other 2 inch by 2 inch coin holders.
On the negative side, it can sometimes be difficult to place coins inside the flexible gasket of the Intercept Shield holders. The holders are also relatively expensive.
Formerly called CoinSafe holders, these all-plastic holders let you view the often neglected third side a coin, the edge. Whether lettered, reeded, or flat, a coin's edge can tell you a lot about a coin, including whether it may be a cast or electrotype counterfeit or whether it was once used in jewelry.
CoinEdge holders are made from Mylar (polyethylene terephthalate) and are safe for long-term storage. They're not the most impressive-looking coin holders but not the least impressive either. You can buy optional accessories, including albums and boxes.
Whitman (or Gallery) holders
These all-plastic holders consist of polystyrene, a relatively safe plastic for coin storage. Made by either Whitman or Gallery, these snap-together holders are an inexpensive way to store you coins. The downside is that coins can slide and bang around inside the holders, potentially causing damage over time.
Whitman or Gallery holders are widely available at coin shows and coin stores and through coin supply dealers.
Made of polystyrene encasing with Mylar (polyethylene terephthalate) windows, these holders are relatively safe for long-term storage. They're attractive, with the encasing available in white or black. They also come with optional accessories, including attractive display boxes and albums.
It can be more time consuming than with some other holders to insert coins into these holders. They may not be ideal for very small or very large coins, which granted are unusual circumstances. With silver three-cent pieces, coins don't always remain in position within the holder, even when you follow the directions for small coins. Large coins such as American Silver Eagles and Bust dollars can sometimes cause the holder to pop open. The company has recommended that you glue shut the holders to keep these very large coins from causing the holder to pop open, though some collectors have expressed the concern that there's a possibility that the glue might damage the coin over time. Check out http://www.eaglecoinholders.com for more.
These plastic (Lucite) holders come in two varieties, one that you screw together, one that you snap together. They're similar to Whitman (or Gallery) holders but are both more impressive looking and more expensive.
Inserting and removing coins, however, can be labor intensive. Coins can also slide or bang around inside, potentially causing damage.
These holders consist of just a round shell that fits snugly around the coin. They're similar to the Air-Tite inner holders. They're made of non-PVC plastic and are relatively safe for long-term storage. The company advertises that some museums use these holders for coin storage. Kointain holders can be used alone or inside other holders or albums.
Coin World holders
This is a new type of coin holder from Amos Press, the publisher of Coin World, too new to fairly be ranked in terms of popularity. These are slab-like holders, the size of ANACS slabs but easy to open and close, which lets you to insert coins yourself. Coin World holders are made of clear acrylic, the black inserts of inert polyethylene. Both are safe for long-term coin storage.
Like slabs, these make handsome holders. Twenty different size holders are available, which fit most U.S. coins. You can write descriptive information on the supplied coin labels, which like the holders are fairly conspicuously imprinted with the Coin World logo. Also available are Coin World coin cases that hold 25 Coin World or ANACS coin holders.
The above aren't your only options for coin storage. Others include slabs, coin albums, coin folders, paper envelopes, poly bags, coin cabinets, coin cases, coin frames, coin tubes ... and pockets and purses.
Recommended coin supply dealers:
Brooklyn Gallery Coins & Stamps
Brent-Krueger Coin Supplies