This important guideThis important guide is the direct result of

Summit 2000, a precedent-setting conference to examine

crucial issues facing dealers and collectors, conducted in

December 2000. Organized by the Professional

Numismatists Guild (PNG) and the Industry Council for

Tangible Assets (ICTA), the summit produced frank and

candid discussions to identify numismatic concerns and

problems, ways to correct them and proposals to plant

seeds for future growth of the hobby and marketplace.

Major topics discussed at the summit included

numismatic education and grading services. One of the first

tangible accomplishments of the conference is this

educational booklet for collectors and dealers to clear up

misconceptions and misunderstandings about coin

cleaning and restoration. Under a committee chaired by

Mark Salzberg, this guide is a cooperative effort by (in

alphabetical order): Independent Coin Grading Company

(ICG); ICTA; Numismatic Guaranty Corporation (NGC);

Professional Coin Grading Service (PCGS); and PNG.

Numismatics is an enjoyable pursuit. This booklet

is designed to help buyers and sellers become

knowledgeable about one of the most important and

misunderstood numismatic concepts – coin conservation.

One of the least understood areas of numismatics centers

around the cleaning and conservation of coins. To many

collectors and dealers, the word “cleaned” sets off an alarm,

since this term is sometimes cited by third-party grading

services as the reason for declining to certify a coin. Of

course, what the grading services mean when they return an

uncertified coin as “cleaned” is that it has been harshly

cleaned, leaving a completely unnatural appearance. But

when a coin is skillfully cleaned by persons having

knowledge of the proper conservation techniques, the

result is often a specimen that’s attractive and desirable in

the marketplace and that will readily be certified. The

widespread confusion that exists over the distinction

between undesirable cleaning versus proper conservation

has alarmed many coin enthusiasts. It is hoped that this

booklet will serve to clarify that distinction and permit

both collectors and dealers alike to trade coins

in an atmosphere of confidence.

The PThe Purposeurposeof This Guideof This Guide

The cleaning of coins has a long history. When numismatics first

flourished, during the Renaissance period of the 15th Century, it

was the coinage of the ancient Romans and Greeks that struck the

fancy of wealthy gentlemen and scholars. These pieces were

typically recovered from hoards buried in antiquity, and it

was not unusual to find such coins deeply encrusted with

earth and minerals. While the gold and silver coins were

fairly easy to clean, due to the durability of their metal,

copper and bronze coins presented a greater challenge.

Even after removal of soil and other contaminants,

these coins frequently retained a fine patina, or

coloration. Typical shades were emerald green and

Tuscan red, and the owners of these gradually came to prize

such patination as a sign of the coin’s antiquity. Even today,

collectors of ancient bronze pieces are drawn by their distinctive

colors, and detailed descriptions of these coins will usually include

the specifics of their coloration. This fact notwithstanding, proper

conservation of newly discovered specimens usually includes

extensive cleaning to remove encrusted contamination.

When coin collecting first achieved widespread popularity

in the United States during the 1850s, many budding numismatists

obtained their specimens from banks, bullion brokers, toll keepers

and others who were likely to encounter large numbers of coins in

the normal course of business. As is true of most beginning

collectors, their first impulse was to render their coins bright and

shiny through harsh cleaning. Many of the surviving United States

coins made before about 1840 have been cleaned at some time in

an attempt to make them look new, much of this activity having

occurred during the latter half of the nineteenth century. This is

particularly true of gold and silver pieces, somewhat less so for

copper specimens.

IntroductionIntroduction

Coins that exhibited normal tarnish were oftentimes

dipped into potassium cyanide to strip away their patina and leave

them bright. Even the United States Mint’s own curators would

periodically spruce up that institution’s collection with a rinsing in

cyanide, a risky business given this substance’s highly toxic nature.

In fact, the poisonous compound is known to have taken the life of

at least one prominent numismatist who, while engrossed in his

cleaning endeavors, mistook the deadly chemical for a nearby glass

of ginger ale. Fortunately, the use of cyanide to clean coins was

abandoned decades ago, and most of the pieces so treated have

naturally retoned to some degree.

It seems that numismatics is nearly the only field in which the

“cleaning” of objects is still perceived as taboo. Collectors are told

repeatedly by columnists and other well meaning individuals in the

hobby to never clean their coins. This advice is offered as a means

of protecting coins solely from clumsy, unskilled attempts at

cleaning, but it has left a lingering impression that any kind of

restorative work is strictly forbidden.

This stands in stark contrast to nearly all other fields of

collectibles. For example, the restoration and conservation of art

works is performed routinely. Indeed, to not undertake this work is

viewed by the art community as negligence. Among conservators of

antique furniture, it is not at all unusual for a piece to be completely

disassembled, stripped of its varnish and then refinished in its

entirety. As long as this work is done with respect to the original

materials and to the appearance of the object before it deteriorated,

the collecting and museum community view such work as not only

natural but quite desirable.

Tarnished silverware and pieces of jewelry are not

ConservationConservationis a widely accepted toolis a widely accepted tool

condemned as “cleaned” when they have had their beauty

restored, so why then are coins? Professional coin conservators are

no less skilled and responsible than conservators in other fields,

so it is time to re-evaluate the cleaning and conservation of coins

in this new light.

The term “cleaned” continues to be widely misunderstood.

Perhaps, this is because the resulting appearance of a coin that has

been cleaned stretches across a broad continuum. There is no

obvious dividing line between what is certifiable and what is not,

yet a professional grader will intuitively know the difference. This

is a challenging concept for the novice collector, and even some

experienced hobbyists are uncertain where the boundary lies.

When it comes to very old coins, such as United States

issues prior to 1840, grading services

typically employ a somewhat more

liberal standard in determining

what degree of cleaning is

acceptable. As noted above, many

early U.S. coins (and world coins of

similar vintage) have been cleaned at

one time or another. To condemn all cleaned coins as

uncertifiable would render an entire segment of the numismatic

market off limits. Some leeway must be given for these early coins,

provided that their appearance is still acceptable.

Indeed, this raises an important point: The numismatic

marketplace usually places cleaned coins into two categories –

those that retain an acceptable appearance and those that do not.

This is an important distinction, because the major third-party

grading services will not certify coins that have an unnatural

Where Where WWe Stand Te Stand Todaodayy

appearance as the result of harsh cleaning. Some of the features

that can make a cleaned coin undesirable are hairline scratches

from abrasive action, a loss of luster from excessive metal removal

and a strange color to the metal (this latter condition is especially

true of cleaned copper and bronze coins).

In contrast, a coin which has been lightly cleaned in a

manner that is consistent with proper conservation techniques

will not only remain certifiable but may even become more

desirable by virtue of its enhanced appearance. Thus, cleaning is

not exclusively a bad thing. It is only the harsh and unskilled

cleaning of coins that harms their appearance and makes them

unappealing. When it comes to cleaning coins, often one starts

out thinking that he or she is an expert. It is only when the sad

results are revealed that collectors and dealers learn just how

challenging the proper conservation of coins can be. It is a job

best left to experts.

When is it appropriate to clean a coin, and what techniques

should be used? These questions can be answered authoritatively

only on a case-by-case basis, yet certain general rules apply. For

instance, coins should be cleaned when such action is needed to

prevent further deterioration. As an example, a coin that has an

active contaminant adhering to it should have this substance

removed immediately.

Perhaps the most frequently encountered contaminant is

polyvinyl chloride (PVC) residue. PVC is a compound added to

many plastic coin holders to make them flexible. Such holders are

suitable for short-term use, such as displaying a coin for sale, but

over a period of years the PVC will leach out of the plastic base

and begin to deposit itself on a coin’s surface. This residue

appears as a pale green film, and it can react with moisture in the

What What to do?to do?

air to form hydrochloric acid. It doesn’t take a degree in

chemistry to imagine what prolonged acid exposure can do to a

coin’s appearance. This is a substance that must be removed, and

the coin’s surface neutralized, yet the proper method of removal

is not common knowledge among collectors and dealers. Only a

skilled conservator should perform such cleaning.

Just as not all surgeries are performed to save a life, the

conservation of coins can likewise have a purely cosmetic aspect.

Some coins are cleaned simply to make them more attractive

while retaining their acceptability within the marketplace. An

example of such an image enhancement would be the removal of

blotchy or irregular toning. The appearance of one or more colors

on a coin’s surfaces – toning – occurs naturally when reactive

metals are exposed to the environment.

All coinage metals react with their environment by

forming new chemical compounds that can alter a coin’s

appearance to varying degrees. Such reactions are scarcely

noticeable on coins made of gold or platinum, as these metals

are highly resistant to their environment. Nickel, in its pure form,

is also quite resistant to chemical change, but when it is alloyed

with copper, as it is in United States coins, it too can be sensitive

to the environment. Of the metals commonly used in United

States coinage, copper and silver are the most reactive.

While toning can sometimes result in extraordinarily

beautiful specimens that are seemingly alive with color,

unattractive or irregular toning reduces a coin’s appeal and is best

removed. This is always a judgment call, and inexperienced

persons are often too quick to eliminate toning that would be

perceived by a veteran numismatist as desirable.

Toning on copper or bronze coins cannot be removed

without leaving a harsh, unnaturally orange color that is not

acceptable to knowledgeable coin buyers. Copper coins that have

been cleaned in this manner are oftentimes subjected to a process

that accelerates their retoning in an attempt to make them

acceptable once again. Fortunately, the major third-

party grading services can spot such efforts and will

reject these treated coins for certification.

Silver and gold coins, however, can be

treated to remove heavy or undesirable toning

without negatively affecting a coin’s

value and appeal to a numismatist.

Indeed, the removal of certain types

of toning is sometimes critical to

the coin’s long term preservation.

Once again, the key to making a

correct call lies in understanding

proper conservation techniques. Anyone

can “dip” a coin in one of the several mild acid solutions that

have superseded cyanide as the cleaning agent of choice, but only

a professional knows when such action is in the best interest of

enhancing the coin’s appearance and its preservation. Proper

conservation also directs that such a cleaning be followed with a

neutralizing action that will stop the chemical reaction from

continuing and will stabilize the coin’s surfaces for generations to

come.

One controversial issue that must be addressed is the practice, or

rather malpractice, of coin “doctoring.” This term refers to any

changes made to a coin’s condition or appearance in an effect to

deceptively enhance its value. This is the ugly side street of coin

restoration that can hamper the efforts of legitimate coin

conservators who seek only to reveal the natural attributes that a

coin possesses already. In contrast, the coin doctor seeks to cover

PProper conservationroper conservationvversus coin “doctoring”ersus coin “doctoring”

up a coin’s flaws with artificial enhancements or to make it

appear better than it ever did previously. His ultimate goal is to

slip a specimen past the third-party certification services and

achieve a grade that does not reflect the coin’s actual state.

Fortunately, the certification services can detect the efforts of

these fraudulent practitioners, and their attempts at deception are

seldom rewarded.

One example of coin doctoring would be the filling in of

tiny nicks and scratches with an epoxy or putty. Another example

is applying artificial or accelerated toning to a coin that has been

improperly cleaned in an attempt to cover up evidence of such

cleaning. This may be achieved by applying a combination of

heat and chemicals, though the resulting coin is not satisfactory

and is easily detected by a professional grader. The coin doctor

may also try to simulate or enhance the attractive contrast

between brilliant fields and frosted devices typical of some

prooflike coins by etching their relief elements with a mild acid

or by plating their flat fields with chromium or some other

highly reflective substance. Years ago, such practices deceived

many collectors and dealers, but the advent of coin certification

services has nearly driven this activity to extinction.

Such attempts at “improving” a coin

through deceptive means stand in stark

contrast to the work of professional coin

conservators. Also not qualifying as

conservation are mechanical repairs made

to coins. These include the filling of holes,

the smoothing out of scratches and the re-

engraving of details lost through wear or

damage. While this work will no doubt

continue to be performed for years to come, it

does not qualify as conservation, and coins

subjected to such “improvements” will not be

graded by the major coin certification companies.

The proper cleaning and conservation of coins is a

partnership between art and science. It is not an

endeavor to be undertaken by the novice, a fact

reinforced by the thousands of coins that have been

rejected for certification by the third-party grading

services. For every coin that an amateur has

improved through his or her efforts, countless more

pieces have been harmed, some irretrievably so.

There are two points that the reader of this

booklet should take away from it. The first is that the

cleaning and conservation of coins is a challenging

task, one that requires years of experience and study

to perfect. In most instances, it should be performed

only by a professional conservator. The second is that

any collector or dealer, whatever his or her level of

skill, should be able to learn which coins have been

subjected to undesirable cleaning. This is simply a

matter of examining pieces that have already

been certified and comparing them

against ones that have been rejected as

“cleaned.” Knowledge is the key to

success in any pursuit, and learning to

distinguish between properly

and improperly cleaned

coins is an important

step in the education of

any coin enthusiast.

SummarySummary