to Coin Cleaning (advanced)
bronze and Romana
cleaning and preservation of Ancient Metal Artifacts from Europe,
and other parts of the world, is a very worthwhile undertaking,
because the relative availibility of these artifacts has never been
greater, and because no matter how available ancient metal collectibles
are now, they have been, are, and always will be rare. The reasons
behind this present and relative availibility are two-fold. Development
or Renewal of historically rich areas has created increased archaeological
activities all over the world, and the use of easily obtainable,
and technologically simple Metal Detectors by the general public
is a positive boon to the collector, or future collectors of ancient
It is truly incredible just how much numismatic
metallica was produced by ancient people, especially the Roman civilization,
which lasted in theneighborhood of 800 years. No matter how this
present plethora of ancient material is viewed though, one aspect
should remain clear in every collectors mind, and that aspect has
to do with the truly finite nature of these ancient artifacts. They
are out of production, and have been out of production for nearly
two thousand years. These times we live in, right now, are very
special, because certain factors have come together, aligned,so
that you, the buyer, can acquire and preserve some of this wonderfully
educational information for yourself.
Of the myriad Bracelets, Rings, Coins, and
other metallic ephemera produced during ancient times, (The coins,
especially, number in the many millions) these myriad durables of
metal cannot come close to stacking up against things like the population
of our world today, which is gargantuan when compared to the number
of artifacts on the market, or destruction of the various numismatia
which has transpired in the last two millenia. The factorys
for these products closed permanently, around the year 1200 A.D.
or so, and will never re-open for business. It will pay if you remember
this as you build your collection, and your view of history will
become greatly enhanced too.
Even though many, many artifacts were produced
during ancient times, all that have survived to this day have undergone
the nearly spectacular Wear-and-Tear of Time, Lots Of Time, a force
that is incredibly powerful in itself, and really must be witnessed
to be believed. By acquiring items of great antiquity you will learn
to recognize some of that power, and it is the purpose of this report
to educate you about that, and to teach you how to easily and safely
halt, and even reverse some of the erosive corrosion that takes
place on the surface of ancient metals.
It is estimated by some that as much as 70%
of the ancient finds of the last two decades have been destroyed,
or permanently damaged, by incorrect cleaning. Not only does that
waste investment of time and money, all the way around, but in the
long perception it is almost a crime against history. It is like
depriving the future of valuable information. Some of this misinformation
was perpertrated to keep "Inventories" of available coins down.
This does not have to be, and by reading this you will be taking
a big step towards safe, conscientious, and comprehensive restoration
of ancient metal artifacts.
The cleaning of metal artifacts should be
attempted with extreme care and caution. There are many techniques
that are actually hazardous, and there is a very good chance of
harming an artifact during its cleaning, rather than enhancing it.
It is fair to say that if an artifact posesses good detail, and
a uniform patina (Layer of oxidized metal) it is best to leave it
as it is. Many times the patina of metal is an actual and entire
Layer of the metal itself, so that its removal also includes removal
of information vital to the items identification, and value. If
you are worried about cleaning a piece of metal, the rule of thumb
is Don't. All types of metal cleaning are erosive, to some
extent. Control and Minimization of this erosive process is what
makes the difference between crude and simple Cleaning, and
One commonality among novice collectors seems
to be the attempt to clean metal by "Shining" it with chemical preparations.
Many acids have been tried with only varying degrees of success,
and they are usually quite dangerous, and are very hard to control.
Many times a secondary chemical needs to be used to halt or nullify
a chemical process begun with acids. Most chemicals used to clean
coins are very carcinogenic. There is a silver dip that is used
by professional conservators, people who meticulously preserve old
plated serving sets and the like, and this dip is called acidified
thioreau. It chemically dissolves silver sulfide. It is highly carcinogenic
although it is sometimes sold in grocery stores as silver cleaner.
The amount of rinsing needed to halt the reaction created by this
treatment prohibits its use on many things, and its a pretty sure
thing that the average person attempting preservation will hurt
themselves, and the things they are trying to clean, with chemicals
I have even heard of people using things
like drano and other chemically hostile agents on old metal, though
I haven't heard a lot of happy reports from those quarters. Electronic
Cleaning is another magnitude of efficiency, at least for the restorer
of ancient numismatics, which of course is the basis of this portrayal.
Be advised that almost all chemical cleaners
are hazardous. Disposal is a real problem and is the Responsibility
of the purchaser. Use only with extreme caution and foreknowledge,
and have adequate safe disposal prepared for the spent chemicals.
We recommend no chemicals for cleaning of ancient metals, and go
so far as to suggest they be shunned completely.
Another big problem with using chemicals
to clean coins is that once a reaction with the metal is begun by
using a chemical on it, it is sometimes almost impossible to stop
it, and there are well recorded incidents of accelerated corrosion
in chemically treated ancient metal. This means that a year later
the coins are in worse shape than before cleaning. Not a pretty
The primary method for cleaning almost anything
is soaking in water. For ancient metals its best if the water be
as free of additives, like chlorine, as possible. Simply boiling
water helps remove a percentage of its added chemicals.
Water is the most effective solvent on the
planet Earth. Thats simply because there is so much of it, and its
liquidity is assured within a fairly broad spectrum of temperature.
Everything alive depends on the diffusivity effects of water on
solids to live. Soaking your coins in water does not hurt them,
provided the water is relatively free of chemicals, and tap water
is usually OK, although watch for sulphur and silver! They
do not mix well at all. The longer coins soak, the more encrusted
dirt will be loosened. That is the name of this game.
The problem with soaking is that to be effective
the metal must be soaked long enough to penetrate to the metal core
of the coin. On the average this takes several years. If the coins
are soaked in anything, and only partially permeated with the water,
any picking or brushing will have adverse effects. There are many
coins that were only partially soaked, then brushed, so that the
outer edges came clean long before the center of the coin, because
of the increased angle of the brush at the edge. By the time the
center of the coin becomes clean, the edges of the coin have been
worn nearly flat with all the brushing. This totally detracts from
the items value and can easily be categorized under the heading
There are many recommendations for coin cleaning
that entail soaking in oil. This is risky business, and may introduce
chemicals to the metal that are not good for it. Soaking in oil
will not accomplish anything that soaking in water does not, and
it adds the problem of removing the oil if that becomes necessary
during further steps of restoration. Oils can sometimes be removed
with detergents, but again, that means more chemicals to upset what
has become, over 2000 or so years, a rather tenuous chemical balance.
It is our suggestion that water be used in lieu of oil, and that
you preclude all use of any oils in treating your coins except perhaps
for some very esoteric circumstances during the finishing process.
Olive oil in particular is extremely acidic, and etches ancient
Picks and Brushes
The most important of the mechanical cleaning
processes are the use of picks and brushes. The use of picks and
brushes, with the emphasis on Picks, is what sets the restorer away
from the novice. Conservation of ancient metal is Care to Detail.
Meticulousness. This is made easier with electronic cleaning
methods, and the two fit together like hand and glove.
A pick is usually a pencil shaped piece of
wood or plastic, with a rounded point on the ends. Occasionally
a sharper point is warranted, and most picks are easily sharpened
with a knife, pencil sharpener or by grinding on pavement.
Another common shape for a cleaning pick
is the spatula shape,where one end of the pick is flattened. Imagine
a worn regular screwdriver head, but plastic. Round pointed picks
reach the places that spatula ended picks cannot, and very Pointed
picks are only for hard-to-get places on the coin, like between
designs or letters, or around the edges. Plastic picks are easy
to obtain and are very inexpensive. Many can be culled from junk
bins at thrift stores. The best are made from a hard type of plastic,
which is still somewhat flexible. Good plastic picks wear from abrasion
on the coins, and will need to be replaced regularly as they wear
and are sharpened.
You will get to know the better plastics
for coin cleaning by experimenting with as many different types
as you can lay hands on. This is easy and inexpensive to do. Any
somewhat flexible and hard plastic that will wear against the metal
makes a good plastic pick. Nylon knitting needles offer the coin
conservator interesting possibilities, as do certain pieces of barware
used for stirring drinks.
The classic numismatic cleaning pick is bamboo.
Bamboo has been used for this purpose for years. Bamboo skewers
that work perfectly for ancient coin and metal cleaning can be purchased
at any hardware or grocery store. Chopstix make great bamboo picks
also, and are of greater size and strength than bamboo skewers.
Bamboo is excellent because as it wears it develops somewhat of
a "Mop" tip meaning the end/tip becomes squished out, and retains
water well, which is a good thing.
When using plastic or wooden picks on a coins
surface always keep the surface you are working on wet. This can
be accomplished by dipping the pick in water and transferring water
in drops to the surface of the coin. You want a wet slurry on the
coins face while you are working; the wetness will decrease the
chance of scratching the coin with an adherence on the end of your
Easy Does It when using picks to clean coins.
You can damage coins with picks too, and its a fine line, which
basically depends on the material of the pick, and the make-up of
the coins surface. Many times strenuous force is needed to get real
hard corrosions to pop off, but there are some coins which are "Mushy",
and when that type of strenuous force is applied, the surface actually
becomes deformed. Thankfully this doesn't happen much. Fingernails
and skin are quite a lot softer than metal, and can be used effectively
in some cleaning processes, to good result.
When cleaning with picks use a back and forth,
or circular motion, lightly at first, and only increasing force
where needed. Again, nine times out of ten you will want to keep
the artifacts surface wet. There are two basic ways to hold a cleaning
pick. One is choked up, with fingers down near the point...this
gives you a lot of control and energy down at the point...the second
way of holding the pick is out near the end...this comes in handy
under certain circumstance when a spring kind of action-energy is
required to remove small and tenacious objects of encrustation.
All this brings us to another method, or
sub-method of using picks to clean coinage. The function of leverage
in the use of picks to clean coins is a circumstance with a lot
of variety, and needs to be studied and experimented with. Many
times the coin is put on its edge, while forceful downward movement
is applied to the tip of the pick. This tends to pop encrustations
off en masse, and can be used to penetrate deep detail, although
this can damage coins which are mushy or cracked. Forward pushing
motions of the pick, on a coin lying on its surface, are another
form of leverage, and can be used effectively in many instances.
After initial cleaning with the picks, further
rinsing can take place, and brushes, even an old toothbrush will
do, will further aid the final removal of grime and encrustation.
Brushes are not recommended for most cleaning but are very good
to have around when they are needed. Brushing is most advantageous
after picking of the metals surface is completed, or near complete.
Picking is, for the most part, the largest
of the cleaning process. It is recommended that all corrosions
be removed by picking and brushing before the coin is finished.
If corrosions are left on the coin they will eventually begin their
chemical processes again, and spread; and as has already been mentioned,
its even possible that they will be accelerated, if they are not
entirely removed from the coin. Much of this process will become
clearer to you, dear reader, as you progress through the next chapters.
It would be best if you read this in its entirety,
twice even, before beginning your experiments.
Tumbling and Polishing
We have reports concerning degrees of success
using tumblers to loosen dirt on coins or other metal artifacts,
prior to secondary cleaning. It is something to think about although
most forms of tumbling are abrasive, and it is suggestedthe restorer
of ancient metallica stay as far away from abrasion in coin cleaning
aspossible. As to the tumbling machines themselves, and their processes,
the more passive vibrating tumblers are by far more desirable than
the rolling drum type, for metal cleaning anyway, because the rolling
drum can become a very strenuous environment once some room is made
inside of it by the wearing down of the load. It doesn't take long
at all to over abrade the entire load if something should go amiss.
Finally, I recently heard of a buddy using an ultrasonic cleaner
to remove the primary layers of dirt from unlceaned coins, and he
happily reports that it worked well. He simply used water with no
chemicals as his fluid. The ultrasonic cleaner is the type of cleaner
used to clean fine jewelry, and the like.
Electric polishing wheels can be made from
small electric motors. This can be very dangerous though, so only
undertake a project like this if you are experienced in mechanics
and electronics. Safety First. Always. These wheels can help finish
a coin, or get some of the more obvious corrosion film off it. A
low speed is best. These are not really good tools for the restorer
of coins, but occasionally they can be used or are needed, though
those cases are fairly rare. If you use a wheel get"Muslin Stitched"
wheels, and any abrasive bar by which to charge the cloth wheel
should be the least abrasive available. Usually you are looking
at grit sizes whose numbers get larger as the grit size gets smaller.
Talk to the salesperson at the hardware store where you acquire
your supplies, or get books concerning metal polishing on wheels.These
tools are actually overkill in many ways though, and just one nice
coin being thrown by the wheel will make you rethink your needs
this way. Anytime an electric device is turned on in a shop, it
is mandatory that safety glasses be worn. You cannot clean coins
without your eyes. Finally, remember this: over-polished coins are
not as desirable as natural looking coins with somewhat of a dark
patina, because the alterations are easily noticeable...nobody really
expects a shiny 2000 year old coin, except maybe gold, and a presentation
of such is always viewed with a healthy skepticism.
The act or process of chemical decompostion,
by the action of Electricity; Websters International Dictionary,
Electrolysis is an act of nature. There are
electrolytic happenings going on all around us all the time. Any
metal immersed in water is acting electrolytically, and every battery
that you use to power a machine or utensil is just a prepackaged
electrolyte reaction. The first electrolysis operation we will begin
with is very basic, and can be considered a passive form of electrolytic
cleaning. It utilizes certain natural phenomena that will allow
you to bypass the necessary soaking time of several years in water
before being able to profitably clean your ancient coins.
If bronze coins are put in a stainless steel
container, then covered with lightly salted water, a natural electrolytic
reaction will begin whereby electrons from the bronze will migrate
to the solution...this take several months but sharply decreases
soaking times in just water. Of course once the outermost layer
of the bronze begins to move, all the dirt and encrustation between
it and the steel turns simply to mud, and is easily removed with
picks and brushes.
There are products
on the market likethe Maggie Pan, or Silver Lion, that work the
same way for silver. They cause a natural electrolytic reaction
to take place between silver and and the material of the pan. These
can be had at any hardware store. They take awhile, and certain
subsidiary chemicals are inherent to the process, most notably dish
detergent of a certain type, but there is nothing too hazardous
about those chemicals, and they do work just fine for passive electrolytic
cleaning of silver.
The best way to speed up the electrolytic
cleaning process is with electricity. This can be done several ways
and each will be explained here. To get you used to it it is suggested
that you start with a small battery, 1.5 volts will do just fine,
and a stainless steel paperclip. Paper clip must by stainless, and
that is the only thing that must be absolutely adhered to, or the
reaction will not work correctly.
Find the positive and negative sides of the
battery and attach small diameter copper wires to each end, about
12 inches long. You can tape the wires on as long as the connection
is good. The thickness of the wire should be about as big around
as a straight pin, or smaller.
Next get a glass jar (Pint or Quart) and
fill about 2/3 of the way full of warm salt water. The amount of
salt is not too important but try to keep it around a teaspoon per
quart. It needs to be "In Solution" so stir the warm water
until the salt dissolves.
Now take an uncleaned coin and "Wire it"
by wrapping some copper wire around it a few times so it is in its
own wire basket. Make a loop at the top of this wire basket and
attach that loop to the wire coming from the negative side of the
battery. Of course you need wire against wire so that electricity
flows. This may entail removing the insulation at the ends of your
wires if the wire is plastic coated. Many times this can be accomplished
with a lighter. Heat the end of the wire until the plastic starts
to bubble, wait a few seconds, then pull the insulation off. Be
careful not to burn yourself. Rubber gloves are nice and should
be worn throughout the entire operation, if possible.
Next wire the positive wire from your battery
to the stainless steel paper clip. Twist the positive wire from
your battery around one end of the clip.
Now immerse both in your glass of salt water.
The wire holder and the coin will begin to bubble immediately. The
bubbles will be very small. If the paperclip is bubbling the polaritys
are reversed on your wiring. After about an hourof this treatment,
maybe more, maybe less, depending on the size of the coin and the
power of the battery, the coin itself will be bubbling over its
entire surface. When it appears that bubbles are coming from the
entire coins surface, that means the coin is conducting electricity.
Electrons from the coin are going into the electrolyte (Salt Water).
As these electrons move they totally loosen any dirt or encrustation
between the surface of the coin, and the solution.
The hard caked on dirt of the ages has now been turned to mud. You
can then pick and brush the coin without damaging it, and all the
dirt will have literally become separated from the metal.
To further empower an electrolytic reaction/cleaning
process, all that is needed is a more powerful source of Direct
Current Electricity, from a transformer. The small black transformer
units (AC Adaptors) that plug into a 120V outlets, which supply
power for things like telephones, answering machines, and computer
printers are ideal for this purpose. These are readily available,
and inexpensive, at any fleamarket or thrift shop, and I think its
safe to say that many of you readers probably have a few laying
around the house, orphaned from a piece of equipment that ceased
to function. Most of these types of plug-in transformers are DC,
Direct Current, and that is what we are after. Read the label and
make sure though, because there are a few made whose output is odd,
like 3 volts AC. Get DC, and use voltages between 4-8 volts, for
most operations. Even if you decide to do multiple coins in mesh
baskets later, its not the voltage you will want to increase, but
the the current, the amperage. The Current is usually measured in
milliamps, 1000ths of an amp, and there are some of these small
transformers rated up to 500 milliamps or higher, which of course
is half an amp or higher.
If you try to learn to only touch the electrical
work with one hand at a time, you reduce your risk of getting hurt
by electricity by 90% or more. These currents and voltages are minimal,
but you can get shocked, and thats never pleasant. Usually
its a short from the AC side that hurts the most, and that will
get your attention 'bout quick.
These small plug in transformers come in
a true variety of shapes, sizes, and values. You are looking for
something from 4-8 volts DC, 100 to 400 milliamps. Anything in that
spectrum will work fine for a quart to 5-quart bath.
Once you get a suitable transformer (I like
6-8 volts, 300-400milliamp) clip the plug off the end of the transformers
output wire, which is the wire you actually plugged into the original
device to make it work. A pair of scissors works fine for this.
Then separate the two output wires by pulling them apart. Separate
them down the wire about 8-10 inches or so. Sometimes there is only
one wire evident during this operation, and in that case it needs
to be stripped, and there will be two wires inside the covering.
There has to be two wires, even if one is very thin. The transformer,
of course, should be unplugged during all the above operations,
and not plugged in at all until everything is in place.
Next, obtain a 1/2 gallon or so Plastic or
Glass container and fill it about 2/3 full of salt water. Warm water
is better, but not entirely necessary. Add about 1 teaspoon table
salt per quart of water, and stir so that the salt dissolves, going
into solution. This is your electrolytic bath, the electrolyte.
Plain table salt, iodized salt, works best. The saltwater solution,
the electrolyte, will get very cloudy as the process components
spend themselves, and again you should prepare against this with
rubber gloves. Here is something you need to know when considering
***From Popular Science Library,
Electricity and Magnetism, Copyright 1922: "...The manufacture of
many of the caustics....are a phase of this art" (Electrolysis).
Caustics are corrosive and will burn your skin.
Wear Gloves, Be Careful.
Now instead of a battery as a power source,
you have the transformer. You will want to hook up the positive
side of the transformer wire to a piece of stainless steel, like
a butter knife; again, this material MUST be stainless, and stainless
butter knives can be had surplus at all thrift shops for about 5
cents each. It is good that these are plentiful, and cheap too,
because they eventually dissolve during electrolytic reaction. If
you can't tell which is positive, and which is negative, it is easy
to see once the power is turned on. If the coin holder/coin
is not bubbling but the butterknife is, just reverse the wires from
the power source to each.
Now repeat what was done during the battery
experiment, but instead of using the wires that were attached to
the battery, you will be using the wires coming out of the 6 volt
I usually just strip the plastic coating
from my wires, about two or three inches off the ends, then twist
the bare wires around the stainless object I am utilizing (The butter
knife), and the wire basket of the Object to be cleaned. Alligator
clips are handy to have around for jobs like this, too, although
they eventually get pretty cruddy, and will break. Try to keep the
connection (Where you have twisted your wires together) out of the
electrolytic bath. It will last longer that way. Whatever
metal hits the bath is going to get chewed.
The coin, or object to be cleaned, now gets
attached to theNegative end of your power source. When the stainless
steel and the metallic object being cleaned are immersed together
in the salt water solution, NOT TOUCHING each other, anode and cathode
are created, in electrolyte, and all that that portends. When electricity
is applied, by plugging the transfomer in, a healthy current begins
to flow between these two electrical entities, through the electrolyte
(Salt water), and quite a number of things begin to occur simultaneously,
one of those things being the cleaning of your coin or artifact.
Electrons are being swapped about all over the place! Once this
operation is going you must always think Safety First! Though chemical
free at the outset, the process will eventually render its components
into new and possibly harmful materials.
One of these by-products produced during this
type of operation is Hydrogen Gas.
HYDROGEN GAS IS VOLATILE AND EXPLOSIVE!!!!!
There is sodium and chlorine going on too,
so watch it. Rubber gloves really are a must.
There is not a whole lot of Hydrogen that
is being produced at any given time, and good ventilation is enough
to easily overcome the dangers of fire, but NEVER do this in a closed
room, and always be VERY aware of accumulations and the possibility
of explosive fire and noxious fumes. No Smoking Use
the same caution you should use every time you put gas in your car,
and you will be fine.
Pre-wiring of coins or artifacts with a single
strand of stripped copper wire, making a sort of a mesh basket out
of the wire, is a very good idea and will make your cleaning operations
expedient and productive. Twist-wire this"Assembly" to the negative
wire of the transformer, and the piece is lowered into the salt
water bath. Small tent clips or alligator clips are handy here also,
to keep the wires in their places, clamped to the side of the jar.
Once all this is done its time to try it out by plugging it in.
Again the wire holding the coin or artifact
being cleaned should begin to bubble immediately. These bubbles
will be very small.
And again, finally, if you put the power
to the bath, and see the piece of stainless steel bubbling, instead
of the coin or the wire basket, you have the polaritys of the dc
power source backwards. Switch the leads and everything will be
fine.The coin or its holder will begin to bubble, and you will have
begun your quest toward professional metal restoration and preservation.
Electricity is now passing between your coin,
and the butterknife, through the solution. At the surface of both
the coin and the knife the molecules of salt and water are being
changed by losing or gaining particles, and so are the stainless
steel and the artifact.
Once current begins to flow through your
artifact, the very outermost metallic layer of the entire object
starts being spewed off through solution to become part of this
orderly and intricate electrical dance. Sometimes it takes a little
while for the artifact to begin to conduct, depending on how badly
encrusted it is, how tight its wire wrap is, or what type of patina/reaction
shell encases it. Once your artifact begins to conduct well though,
its not long before it should get pulled, because this conduction
will loosen up EVERYTHING between the metallic surface and the solution,
meaning encrustations, plain dirt, and the like. Once the initial
molecular layer of metal begins to move off the entire artifact,
the rest is overkill. Many times though, it will appear as if the
coin is conducting well, but the really tenacious flakes or deposits
will remain after removal from the bath and the picking/brushing/drying
stages. It is generally a good idea to re-immerse these unless the
leftover detritus can be removed by dry picking, or other means.
Re-immersion is the rule, and to get the corrosions off in any other
way is true rarity. There is one trick beloiw, in the trix section,
that might come in handy along these lines, the use of epoxys, but
that is chancy and should only be tried on specimens you are not
afraid to damage.
Many times when multiple coins are being
cleaned in each pot there is a cycle that develops, whereby half
or more of the coins get shunted back to the bath. This method is
highly preferable to over cleaning. Over Cleaning should always
Here is the Number One Rule of Electrolytic
Monitor Constantly and Check
You will learn to recognize various stages
of the cleaning process after you clean 50 or 60 coins. Different
patinae act differently too. The only way you are going to get it
is to Monitor Constantly, Check Often.
The best sign that your artifact is conducting
is if it Itself is bubbling, as well as the wire it is wrapped
If your bubbling ever stops that means the
operation is not doing what it is supposed to. Something is wrong.
Most common causes are deteriorated stainless steel, a bad connection
at the stainless piece, corrosion of the transformer wires at the
bath, or a problem with the power supply.
Sometimes it helps promote cleaning to add
small amounts of salt, and it is not a bad idea to add a little
salt each time you add water. You will have to add water regularly
as the solution is transformed. The pots can be kept going for hundreds,
maybe even thousands of cleanings, by just adding saltwater when
the solution level drops. Remember though that the more cleanings
that take place, the more free metal salts and other transformed
chemicals like sodium and chlorine (Table Salt) there will be. Disposal
is the responsibility of the creater, and should not be looked upon
lightly. The best way to dispose of the spent solutions is to make
a settling tank out of a small plastic drum. Allow the top to be
open and let the fluid from the spent chemicals dry to a solid.
This can be dumped at landfills after informing the attendant of
its origin. They will instruct you from there. Its possible the
solid waste can be boxed and bagged and discarded as regular garbage.
But be careful you might be throwing away good things. Check with
refineries in your area. They may be willing to buy the solid waste
of the electrolytic cleaning process. There are a lot of metals
present in this solid waste that can be used further, and possibly
In a professional electrolysis set up there
are usually at least two pots running, as well as a fan, which cools
the transformer power supplies (one for each pot), and also ventilates
the work area; There is also a toaster oven, and a warmerplate (More
about these next). These all get plugged into power strips, the
type with 6 outlets are very good because the transformers are bigger
than a regular plug of course,covering usually at least two of the
outlets in any power strip. Everytime the transformers are on, at
least one small computer fan is running too, whose airflow is directed
at the power supplys, for cooling purposes, and at the electrolysis
pots, to disperse gases. All professional electrolysis work is done
out of doors, like on a screened-in porch. Warmer plates can be
used to keep the electrolysis pots at about 100-120 degrees, which
helps the solution work better. Not necessary, but its a trick that
will speed things up a little more if needed. Most if not all of
the Spanish shipwreck treasure salvaged from Florida Waters has
been cleaned electrolytically. It is a time honored and very effective
It really is vital to cool these small
wall unit power supply transformers. They will burn out quickly
if not auxiliary cooled. Many only last for several dozen coins
before burning out if not auxiliary cooled. If the fan is used to
cool them during operation most will last through thousands of cleanings.
The electrolysis process of cleaning metals
is by far the easiest and most effective method for preservation
of numismatic metallica. It is another magnitude of efficiency,
especially when considered against harsh and dangerous chemical
treatments. Except for very odd circumstances it can and should
be used exclusively for cleaning iron, brass, bronze, steel, copper,
silver, and gold.
The Toaster Oven
The use of Heat is a bona fide electrical
aid to cleaning metallic artifacts. It should be used in conjunction
with electrolysis, and after electrolysis. There are a few tricks
to know about heat that will make your coin cleaning more productive.
Once a coin has been cleaned it needs to
be thoroughly rinsed then thoroughly dried to see the contrasts
of places that have been missed, and to halt any reactions that
water might precipitate. This is best accomplished with a heat source
such as a toaster oven. The toaster oven is an all around metal
cleaning tool, and they can be obtained very inexpensively at any
thrift store or fleamarket. Every good bench needs one. Be careful
and respect it though. It will burn many things, you included.
There are many instances of coins that have
cleaned up nicely except for perhaps a spot or two of hard reaction
shell patina that would just not popoff. Before attempting heavy
duty methods, or re-immersion in the bath, something that works
fairly well is to take a coin like this and subject it to high heat
(300-400 degrees), then immerse it in ice water right from the oven.
Many times this will loosen the tenacious flakes of patina that
were not removed in the bath.
Both high and low heats can be used for various
things when cleaning and restoring metallica. Heating below 500
generally cannot hurt the metal, and many times it actually restores
the original color/patina-look to the coin, darkening the old metal
without chemicals or other artificial means. If you get an oven
with a metal top it makes a great drying table in between stages
of cleaning also. As has been stated, a lot of time during their
cleaning, coins need to be dried, because any left overshell/patina
will many times show up on a dry coin, that you cannot see when
the coin is wet. You would not want to finish a coin that still
has patina on it. To arrest corrosive reactions, all previous corrosion
needs to be removed from coins that have been buried.
Other than removing the old patina shells
electro-chemically, Dry Heat is the main tool used to arrest corrosion.
If the corrosions are extremely detrimental and destructive, the
best thing to do to keep the process from beginning again, is to
heat lengthily, and then coat with an airtight finish.
This is not a guarantee that corrosion has
been arrested, but it is really the best you can do. Many times
it takes years to see if a treatment not only worked, but held.
many archaeologically restored coins of 20-30 years ago, the types
impregnated with chemicals, did not seal the air from the metal
and are now just blossoms of metallic oxides. Its always
good to take photographs of coins, even during the process, and
especially finished products.
The Romans in particular silvered a lot of
coins by a depletion process, whereby silver was added to the copper
alloy, like 5% or more, then the flans/planchets were immersed in
a light acid that selectively etched only the copper. The hammered
surface of this type of coin appeared silver (until worn) because
the hammering action created a semi-permanent weld of the silver
deposit at the surface of the coin which was left as detritus after
the depletion acid bath. Many times a"Repletion" effect can be observed
on these coins after electrolysis, especially if the coins are subjected
to high heat, say 300 degrees+ for several hours. It doesn't work
on all of them, but some of the results are surprising. After
this process finishing with rubber (See Below) worx well many times
Finally. Electrolysis and heat as electronic
cleaning methods for coins are the most preferred for their overall
comprehensiveness, and ability to halt and arrest ongoing reactions
that, if left unchecked, would fully obliterate numismatic record
in as few as 5 millenia.
Beeswax, Pine Resin, and
On fine and whole coins with no problems
it is best to apply a thin coat or two of clear acrylic spray after
cleaning and heat treatment. If the coin is well patinaed and not
cleaned electronically it is also best to use acrylic spray. Most
of the sprays can be removed with acetone later if they need to
be. This clear spray tends to lighten the coin up a little, so if
the coin is too light already, think twice before spraying it. Or
put heat to it longer to darken it up. Do not spray coins when they
are hot because the plastic spray will harden before bubbles get
a chance to come to the surface and it will foul the finish. This
type of spray is usually very flammable and not good to breathe.
On coins that have had problems, like pitting,
wear, broken, or too light, a good finishing treatment is beeswax
applied during the final heat treatment. This soaks into the porous
metal and seals it somewhat, also smoothing out discriminations
in the surface a little. It can be lightly polished with paper towel
once it is dried and hardened, and it will still keep its color.
You need to wipe the hot wax off the coin as soon as it comes out
of the oven, which means Wipe It Hot, and that will impose
certain logistics upon you concerning your preparation. Beeswax
is very reasonably priced and readily available. It is perfectly
safe to use. The only drawbacks to wax is that once its used it
is the devil itself to remove, and it is not a perfect seal on porous
metal, and may allow further oxidation, corrosion, in the future.
I have sprayed over coins that were treated with beeswax, after
making sure any excess wax is removed, and they seem to be very
presentable and are effectively sustained. You have to experiment
and see what works best for you. Pine resin can be used instead
of beeswax, or in conjunction with it. It is best to experiment
on lesser coins if you are unfamiliar with a process, and learn
from there. Beeswax is virtually unremovable though, and does
not seal air as well as removable plastic spray finishes.
Eitherway, these three finishing processes will not harm cleaned
coins, and can be further modified if the results are less than
one had hoped for. As a rule, stick with spray 99% of the time or
more, because it seals the air out, and is easily removed in the
event a future numismatist finds it necessary to do so.
There are other finishing treatments too,
though they become more specialized and expensive, and dangerous
to use. Many times exotic finishes preclude a natural look, and
serious collectors wish to obtain only coins with darker finishes,
in as natural a state as possible.
Hopefully you have been saving your dud coins
too...most of that will be copper, but there will also be some silver,
and traces of gold, because of the primitive alloying process. Here
we cite The Popular Science Library from 1922, (This refers to the
amount of trace precious metals in natural alloys in MODERN Times!):
"...The statistics in regard
to copper refinement for one year are as follows: During the electrolytic
refinement of 279,000 Tons of copper, the by product of precious
metals that were recovered was 27,000,000 ounces of silver, and
346,020 ounces of gold."
This means that the earlier smelting and
refining processes,which many times used metal straight from the
mine, were incapable of removing these traces of precious metals,
and a lot of the natural copper and other metals from earliest times
are mine run metals and have varying percentages of gold and silver
in them. This can be sold for profit by the astute coin cleaner.
Electrolytic refining is an art unto itself, and nearly 100% efficient,
as opposed to ancient refining methods.
By dud coins it is meant cleaned coins that
are flat or irretrievably broken or corroded. No information. If
you are buying uncleaned ancient coinage now, you need to electronically
clean even the groatiest of coins you buy, because even some of
the most unlikely pieces turn into jewels once their shell is removed.
A trick when using electrolysis, especially
when you have coins in the bath for their second time, is to turn
the process off for an hour or so, and let everything cool down.
Then restart the process by turning on the electricity for about
10 more minutes. This will many times remove or loosen really hard
spots of corrosion that would not budge from the coins surface previously.
When wiring a find onto the negative end
of the transformer, it is many times advantageous to pre-wire the
coin or artifact, then hook up the transformers wire to that. Single
strand copper wire of fairly sturdy grade, again, about the diameter
of a straight pin, is best, and it can easily be wrapped around
the coin 3 or 4 times so that it is in its own little wire harness,
or basket. This method can be further modified to incorporate many
coins at once, although time in the the solution will be increased
the more coins you add.
One of the best last-step cleaners for ancient
coinage, silver included, is non-abrasive pencil eraser, gum rubber.
It takes a lot of pressure, but works well in some areas, and it
is the least erosive of mechanical methods of cleaning. Pencil erasers
can be added to chopstick picks and the tool becomes not only dual
ended, but dual purpose too. Erasers that are used to remove
ink are a no-no when cleaning coins. The abrasive in them will mar
a coin every time.
References are made by Gerhard Welter concerning
shock treatment of metal, to "Dis-Adhere" patina or reaction shell
from the surface of the coin. This occurence is easy to observe
when attempting to straighten bent coins. The two ways to straighten
bent coins are hammering (Use leather and plastic pads between the
surfaces and the coin) or by squeezing in a vise/press, again between
two heavy but sympathetic materials. Where the coin gets re-bent
to shape, the patina or antique finish gets crackled off the metal
most of the time. This could be helpful in loosening coins that
have become corrosion-welded together, also. Heat and Ice
treatments have worked on corrosion-welded coins before too.
Here is a fool proof and easy way to clean
all coins, even American Coins dug from the Earth. Put the coins
in a pan that drains and will not corrode, ceramic is best, and
put that on your roof and forget about it for a couple ofyears.
Maybe longer, maybe not quite so long, but for a good while. Put
it where the sun can get it regularly....that is a long term erosive
force. Many time surface finds are extremely clean on their "Up"
side, but still dirty from being buried on their underside. This
is easily observable and has been noticed by many. The cleaning
of coins and other metals by exposure takes a lot of time, but there
are some things found here that cannot be cleaned in any other way
without drastically reducing their value. There is a story
of an Irish farmer finding a large corroded/encrusted ring
of metal while plowing one day. He hung it in a tree, thinking
it was a defunct farming part, and wanting it out of the way of
his machines discs. About a year later he had occasion to
visit that tree again, and happened to look up, to see a beautiful
Druid gold torc, which in the year it had been exposed to the weather,
had "Worn" back to its natural state, and was perfectly clean.
All without chemicals or other treatment. The weather is a
powerful force and can be put to work to your advantage.
One way to remove otherwise irremovable encrustations,
or to remove just minor encrustation on an otherwise nice coin,
is to coat the side that has the encrustation with a plastic epoxy
adhesive, and let it harden. After it hardens carefully pry this
epoxy layer off the coins face, and many times it will remove loose
encrustations. I have been pleasantly surprised at the results of
this method many times. I usually make the epoxy more a droplet
than a coating, as it provides greater solidity during removal.
Reaction Shells (Patinae)
The Restorer of ancient metals will eventually
begin to recognize the gargantuan force of time by its look. There
are many aspects to the look of the ages. Different visual input
can clue the discerning observer to certain traits that will allow
greater utilization of time and resources.
Coins that are heavily coated with dark brown
patina seem to be the best as concerns state of wear. Some people
call this "Black". There are a higher incidence of Mint/NearMint
coins from metal encased in that type of shell. Sometimes it is
true aggravation to get the conduction going with them, because
that particular coating can be hard, but once it starts its done
quickly and the shell of patina falls right off in flakes.
The next best look to many high grading conservators
is the dusty brown/tan that appears frosted onto a coin. You could
brush for days and just get about half the compacted dust off those
coins, but that type of reaction shell hides a great many near mint
state coins, and nobody can know until they are cleaned, because
usually there are no visible surface details at all.
The green copper oxides seem to be the most
destructive of all the patinae, forming lots of pits. Green encrustations
(Bronze Canchre, Cancre, copper chlorides, etc) are the worst thing
to see. If the coin is entirely enveloped in green,and showing good
detail, it is usually best to leave it as is, maybe spraying
with clear acrylic, because the removal of that patina is actually
a layer of the oldest metal, and you lose detail, and usually alot
of it, when a nice total green is taken off the coin. The best way
to rid yourself of all these coatings (Reaction Shells) is with
the aforementioned electronic process of electrolysis, in conjunction
with a well practiced regimen of picking, brushing, heating and