First published: June 1994

Some people acquire rare coins primarily for pleasure,
others primarily for profit. Some regard themselves first and
foremost as collectors, others first and foremost as

However you view yourself and your coins, you’ll never
achieve your objectives unless you take care of those coins
— for protection and preservation are the common allies of
collectors and investors alike, and deterioration and damage
are the common enemies.

In 1985, a collector client came to me with a group of
coins that once had been — and still should have been —
truly incredible. The group contained a Liberty Seated half
dollar with spectacular cameo contrast and beautiful toning
… several highly desirable and scarce-date Indian cents,
including an 1864-L, an 1877 and a 1908-S … and a high-
grade, scarce-date Barber dime.

All of the coins were well preserved — or at least the
client thought they were, since all had been stored in nice,
soft vinyl flips. The trouble was, those flips were made of
PVC — polyvinyl chloride — and the coins had all corroded
while in storage.

The moral of the story is that a coin holder costing
just a couple of cents can easily ruin coins costing many
thousands of dollars.

Coin storage problems are a matter of utmost concern.
Whether you buy coins to hold for long-term gain or to sell
in a nearer term when the time is opportune, you stand to
lose a great deal of money if those coins deteriorate while
in your possession.

The preservation risk is a clear one. If you buy a coin
for $1,000 and drop it on the way home and the coin gets a
scratch on it, that $1,000 coin can plummet in value to $100
— even if you got good value in the first place — because
of the loss of condition.

Many collectors and investors have experienced similar
losses in the value of their coins — not because they
dropped them, but because they stored them in unsafe holders
or unsafe environments. Yet, in many instances, they haven’t
sought or received advice on how to avoid recurrences.
Clearly, there is a lack of appreciation for the seriousness
of the problems and a lack of education on how to combat

Coin preservation is a never-ending struggle. Coins
begin to deteriorate the second they are produced. Every coin
you see — even the highest-grade mint-state coin — is in an
intermediate stage between having been completely brilliant
and turning completely black.

Coins are affected by a multiplicity of variables. Bern
Nagengast, a well-known authority on coin preservation who is
the principal of E&T Cointainer Company in Sidney, Ohio, says
the rate of a coin’s deterioration depends primarily on the
metal of which it is made, the atmosphere, the contaminants
on the coin’s surface and the handling of the coin.

As the owner of a given coin, you can exercise control
over a good number of these factors and thereby slow down —
and perhaps all but stop — the deterioration of your coins
and keep them in the same level of preservation over the
years. You owe it to future generations of collectors to do
so — to maintain your coins in the same level of
preservation when you store them. And if moral and
philosophical considerations aren’t persuasive enough, you
owe it to yourself–because if you don’t, you stand to lose a
whole lot of money.

Let’s consider the most important factors affecting a
coin’s long-term life.

The atmosphere surrounding a coin certainly can have a
significant effect on how well, or how poorly, that coin
holds up.

According to Bern Nagengast, normal pollutants found in
the air can cause serious long-term problems by combining
with oxygen to damage a coin’s surface. Artificial gases
produced while a coin is housed in a plastic holder, coming
from the plastic itself, also can cause major damage.

The atmosphere contains moisture and dust, and both are
dangerous to a coin, for both carry oxygen into intimate
contact with the surface of that coin.

Since we don’t have much control over the air around us,
the best way to protect a coin from the atmosphere is to
place it in a container that’s as airtight and inert as
possible. That way, impurities in the air will be kept away
and, at the same time, the container itself won’t contaminate
the coin.

The problem is, no coin holder yet devised is absolutely
airtight. Even coins that have been encapsulated in sonically
sealed, tamper-resistant holders by the major grading
services are not 100 percent impervious. These holders are
somewhat airtight, and the plastic of which they’re made is
chemically inert — but they’re not completely airtight, and
air does come in contact with the coins inside, though
admittedly at a greatly inhibited rate.

This is not to minimize the importance of safe and
effective holders. On the contrary, they can play an
invaluable role in safeguarding your coins.

Susan Maltby, a well-known preservation expert from
Toronto, recommends holders made of either Mylar,
polyethylene or polypropylene. All three are tough, stable
compounds — and unlike PVC, they won’t break down readily
into their chemical components.

As for PVC, Sue Maltby has a three-word recommendation:
“No, no, no!”

PVC “flips” gained wide popularity during the coin
market’s boom years of the mid- and late 1970s because they
are exceptionally clear and flexible. This seemed to make
them an ideal way to store and display rare coins. In time,
it became apparent that these relatively minor conveniences
came at a very high cost — for when heat and light act upon
PVC, it breaks down chemically and hydrochloric acid is
released. This, in turn, can cause chemical damage to the
surface of the coins that the holders are supposed to be

Often, plasticizers are used to enhance the chemical
properties of PVC holders, and these can ooze out and form an
oily film upon the coins, greasing the skids for still
further damage.

The perils of PVC were publicized extensively in the
early 1980s, and since then there has been a noticeable
decline in the use of such holders. Obviously, though, not
everyone has gotten the message: Recently, the Numismatic
Guaranty Corporation of America (NGC) issued a press release
reporting that it has received a substantial number of coins
with PVC damage.

Those coins were submitted to NGC by dealers, collectors
and investors seeking to have them certified and encapsulated
by the company, which is one of the nation’s leading coin-
grading services. Instead, they got their coins back
uncertified, since NGC and other grading services make it a
policy not to grade damaged coins.

Mark Salzberg, NGC’s president, suggests that many of
the damaged coins now entering the marketplace may have been
set aside years ago, before the risks of PVC were fully

“Collectors and investors should check any coins they
have put away — in safe deposit boxes, for example — to
make sure the holders are chemically inert and the coins have
not been damaged while in storage,” Salzberg said.

Those who suspect that their coins may have been exposed
to PVC should remove them from their holders immediately, he
said, and take or mail them to a dealer familiar with how to
neutralize the chemical and, if possible, remedy any damage.

“We’re alerting NGC-authorized dealers to the problem
and advising them what can be done to deal with it,” he said.

Of course, PVC isn’t the only source of potential damage
to your rare coins. Other caustic chemicals, such as
compounds containing sulfur, can harm them, too. Even you
yourself could be the source of damage: If you chanced to
touch a coin with a perspiration-soaked thumb, for example,
that coin could end up with a thumbprint permanently etched
in its surface.

This, by the way, is another illustration of why
“slabbing” won’t necessarily guarantee the permanent safety
of your coins. If your sweat-soaked thumb came in contact
with a coin and the coin was then certified and encapsulated,
the chemical damage caused by that contact could continue to
develop even within the sonic seal of the “slab.” It might
take longer for the etching of that thumbprint to appear, but
eventually it would rear its ugly whorls.

Frequently, coins carry the seeds of their own
destruction — without any help from the atmosphere or other
external factors.

Bern Nagengast and Susan Maltby share the view that
however pristine they may look, coins are essentially dirty.
During production, the metal used in coins is rolled,
punched, annealed, die-struck and handled by various
mechanical devices. Even proof coins are contaminated with
metallic particles, and even the most meticulously preserved
business-strike coins suffer from a multiplicity of
contaminants: oil and grease … rag dust … bag dust — you
name it, they’ve been exposed to it.

After the coins leave the Mint, they’re further
contaminated by counting machines and handling. Even when you
simply hold a coin, you’re contaminating it — and sometimes,
the contamination can be devastating. If you eat a pastrami
sandwich over your proof Trade dollar, you’re contaminating
it. If you have dandruff, you can contaminate it. If you eat
chicken wings and then touch a coin, you can permanently ruin
its level of preservation. If you talk over a coin, the
saliva from your mouth can land on the coin and turn that
area black — and then actually penetrate the surface of the

How you hold a coin can be important, too. If you don’t
hold it properly by its edges and the mishandling causes
abrasions, you can ruin the coin. Likewise, a coin can be
damaged by coming into contact with other coins or rubbing
against some other foreign substance — even a velvet cloth.

Another crucial aspect of coin preservation is coins’
metallic makeup. Some coins are more prone than others to
chemical and environmental damage; some, by contrast, are
more resistant.

Gold retains its mint luster almost indefinitely —
although, as Sue Maltby notes, that depends on how pure the
gold is. Some gold coins contain copper — and in such cases,
the copper might cause them to break out in spots.

Silver is quite resistant to corrosion, but it’s highly
susceptible to tarnish, especially in the presence of sulfur
compounds and nitrates. And Bern Nagengast points out that
sulfur and nitrate compounds are frequent components of air
pollution today, so these are real concerns.

Copper coins are especially susceptible to damage from
airborne particulate matter, and can break out in spots
virtually without notice. For this reason, you should take
special pains not to store copper coins in a moist

According to Susan Maltby, vulnerable metal coins will
start to corrode when the relative humidity in the
surrounding air rises above 35 percent. Obviously, then, the
risk of corrosion is higher in a damp, humid place such as
Florida than it is in a drier climate — the kind found in
Arizona, for example.

To combat this risk, you need to create what Sue Maltby
calls a proper “micro-climate” — a neutral, acid-free
climate — for your coins.

One way to accomplish this is to treat the air
surrounding the coins — the air in your safe-deposit box,
for example — with a vapor-phase inhibitor. This is a
substance that changes the molecular composition of the air
to retard the process of tarnishing.

Sue Maltby reports that museums have used such products
for many years. She cautions, however, that vapor-phase
inhibitors tend to be specific for certain metals; in other
words, a “VPI” meant for use with silver might be of little
value in retarding damage to gold or copper coins.

Silica gel also can be beneficial, she reports. If
you’ve purchased a new camera or radio lately, you’ve
probably noticed a small packet of silica gel in the box.
Silica gel and silica are “very handy for maintaining a dry
environment,” Maltby says. Basically, they serve as sponges,
drawing all the moisture out of the air.

Sue Maltby also recommends dipping your coins in a
neutral solution, such as alcohol, before storing them. For
his part, Bern Nagengast advises that you treat them with an
evaporative freon solution such as trichlorotrifluoroethane.
This protects the surfaces of your coins from environmental
damage, yet is harmless itself to the coins.

Obviously, proper preservation is a lot more complex
than simply sticking your coins in plastic holders, tossing
those holders in your safe-deposit box, then walking away.

As with any other aspect of coin collecting, though …
or any other aspect of life in general … the more you put
in, the more you get out.

And if you don’t expend enough time and effort
protecting and preserving your coins, what you get out of
your safe-deposit box may prove to be a whole lot less than
what you put in.

[Note: Since this article was first published, new production
of trichlorotrifluoroethane, a highly evaporative freon, was
banned because of its destructive effect on the earth’s protective
ozone layer. And a superb new product designed to maintain and
protect coins, Intercept Shield, was introduced by John Albanese.]

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