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| Coin Cleaning Guide | |||
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Definition of Patina: The colour or incrustation which age gives to works of art; especially, the green "rust" which covers ancient bronzes, coins, and medals. If you're new to the hobby of ancient coin collecting and cleaning, it's very easy to strip a patinated coin bare to shiny bronze disc -- but this is the absolute worst thing you can do! A coin with a patina will almost always be preferred by collectors and worth more to you than one which has been stripped down to the bare metal. It's a common mistake for people to think that buying someone else's over cleaned bare metal roman coins is preferable to buying a coin which has a green, black or brown patina. These over cleaned coins will be worth next to nothing. Very few serious collectors will buy something that looks like it was made yesterday. Patina is also an indicator of age and adds a certain elegance to what can sometimes be a routine coin. In the early stage of learning to clean coins, I suggest you experiment on identified low detail coins or those that are not particularly good fiscal earners. So if and when mistakes are made you don't end up ruining the surface of your favourite coin. Image A is a nice looking coin but it has been overcleaned and only normal tarnishing from contact with air has taken the sheen from it whereas Image B has been nicely cleaned and left with the patina intact. (Image A) What equipment will I need to clean my coins? You may need to use a wide variety of cleaning tools and methods to clean your coins, and it can be said that no one method suits every coin cleaner. Although there are many methods to clean coins, the basic tools are generally the same. The following, along with a good light source, are common tools used for coin cleaning: • Brass Brush Look through your uncleaned coins and try to group them according to levels of encrustation. The coins with the most visible detail and least amount of encrustation should be kept separate. The coins which are heavily encrusted may need many more days (possibly even weeks or months) to clean depending on your method chosen. Try to seperate them into 3 groups and mark each jar/container accordingly "Light Cleaning", "Moderate Cleaning" and "Heavy Cleaning/Encrusted" Although coins with heavy encrustation usually require more soaking than coins with a small amount of encrustation, they should all be soaked overnight to begin with. Sometimes heavily encrusted coins don't end up requiring as much work as first thought, so it pays to start with a light cleaning and then move on to heavy cleaning only if required. The key to coin cleaning is small detailed steps! Soak your coins in either distilled water overnight to help facilitate the removal of dirt. It's best to use labelled glass jars with lids. Labelling the jars helps you to remember what stage the coins are up to, as well as preventing the jars getting confused with junk and thrown out during the spring clean! If you use olive oil and spill some on your carpet you will have a hard time removing it. The idea behind soaking your coins is to remove the dirt that can covers most of the coins. These are usually a pleasure to clean in comparison with the mineral encrusted deposits, which can form nodules on the surface of your coins. While the coins are still wet, gently brush the encrustation with a hard toothbrush. With a little luck this may be all that is required with some lightly encrusted coins and may reveal a treasure that's over 2000 years old! If you find some coins which resist your initial attempts to clean them, you need to persevere. Simply go back to Step 2: Soaking, but this time let them soak for a week or so. Check on them daily to see if the Distilled Water is becoming discoloured due to the dirt being removed from the surface. Some hardy coin cleaners have been known to leave their coins soaking for up to a year before cleaning them. Brushes made from Brass are preferred as they tend to minimise the damage done to the Patina. Silver brushes don't tend to harden the encrustation like brass brushes and may be preferred for work on more detailed areas of the coins. Try to not use a brass brush on a coin that seems to contain only surface dirt and can be removed with distilled water and a light brushing with a toothbrush as it may disturb or damage the patina. You may find a coin that cleans up well but lacks detail due to dirt still firmly wedged between the letters or symbols on the coin. For those with steady hands, a toothpick or dental tool with a magnifying glass/microscope can be used to etch around the uncleaned areas and bring out the detail of your coin. Always be careful to not damage the patina. More soaking may be required as you go to loosen up more of the dirt and make the coin easier to clean. For car enthusiasts "detailing" is working on the final presentation of your car ready for show or sale, it involves making your car as perfect as can possibly be. In the world of uncleaned coins it is no different. You can clean a coin and many people will be happy with their cleaned coin at that stage but if you put that coin under a 5000 kelvin daylight light and photograph it the residual dirt between the lettering, in the Emperors hairline and bust profile will be illuminated for all to see! To remove this dirt we use some of our finer tools in the coin cleaning arsenal - namely the pin vise. A key to doing this successfully is a good light source and a desktop lamp can provide this but only at a "daylight" level. The afforementioned bulb can be purchased for the same price as other bulbs and the lumen output (that which relates to the intensity of the light) is rated according to lumen output. For our purposes 5000k is ideal. Positioning your coin to alleviate chronic hyper extending of the neck is just as important in coin cleaning as you may be spending a fair bit of time detailing your coin to get it perfect. Once you have this done we can begin detailing your coin. I suggest starting on coins which you have cleaned and retained the patina but look like they arent going to be your top end cleaned coins, thus if you slip with your pin vise you havent scratched the delicate patina. The keys to doing this succesfully are knowing how steady your hand is and taking the time to do the detailing properly. Start slowly and gently pick the dirt from the recessed parts of your coins following the hairlines on the busts, the shapes of the letters etc, this helps avoid accidental scratching of other areas if you slip or arent paying attention. It sounds like I am belabouring the point here but this is one of the most important aspects of perfecting your coin cleaning skills. Nearly anyone can clean a coin but how many can do it very well! After you have gone around all areas of your coin and removed the dirt in accordance with the principals above try using your silver brush and wiping that dirt off. If you dont have a silver brush then use a very soft brash brush. Now hold your coin in the light and see how much dirt is left. If you are lucky the initial detailing and subsequent brushing will have removed it all and no further detailing is necessary. However it is more likely that your coin still has other areas left that still have dirt remaining. I personally like to be uniform in my method of detailing and will work on one area at a time and methodically clean that area before moving onto another. I dont jump in and "pick" the dirt at random as this will lead to mistakes. Try to develop good habits now and youll save many coins in the long run. When a printer is printing a document is does it line by line and if you can learn to detail according to that prinicpal then what you will succeeed in doing is avoding having to go over the same area twice or more and save yourself a lot of time in the process. Above all else when you are in this process be gentle - dont dig the pin vise into your coins surface. You are attemtping to remove dirt NOT smooth the surface of your coin and clean it in one sweep. After you have done this return to the silver brush and polish your coins. Any hazing (a sheen left from the brush use) from the silver brush can be wiped by hand or cloth but for brass brushes this bronze hazing may need a heavier touch. At this point and for those less fiscally challenged you may choose to employ the use of a high powered microscope to help you detail your coins. This is taking coin cleaning to the next level and really can help you get some amazing detailing of your coins done but for an investment of 1-300$USA you would want to be cleaning a lot of coins!!! If you have succeeded in cleaning your coins but they still remains sullied by the medium you used to clean them, rinse with Distilled Water then gently wipe off all traces of it and allow your coins to air dry before placing them in coins slips or albums. This will help preserve your coins and not deteriorate their quality. The use of renwax has been lauded by many as a preservation agent and rightly so but I have found a few drawbacks in using it on your cleaned coins. First I have to say if you havent detailed your coins then DONT use this - your coins will look quite poor as presentation pieces as the ren wax will preserve the dirt for all to see! I dont personally use this on 99% of my coins - why? Its just not needed. If you have retained the patina of your coins and its sound and not missing in areas then I dont see the reason for using it. On coins which have broken patinas or in the absence of silver brush use as a finishing tool then by all means use it. It can add a lustre to your coin. Minimal amounts work better than smearing it on like vaseline. Remember to let it dry before you buff your coins or youll just end up brushing half of it off again. Help, some encrustation refuses to move! After trying the first 4 cleaning steps above, if the encrustation refuses to move then you may need to try harsher methods of cleaning. Don't despair at the encrustation on these coins as what's hiding underneath may very well provide you with a few pleasant surprises. One of the harsher methods is to dilute lemon juice with water to 25% (25% lemon juice / 75% distilled water). Try submerging your coins in this mixture for 15 seconds, then rinse in distilled water to halt the chemical reaction and dry them. Check it to see if anything has occurred, such as the removal of dirt, patina loss or encrustation loss. You may not have noticed anything happen to your coin, and you can try it a few more times to see if something does happen. But be forewarned - lemon juice will, given the chance, strip your patina off or at the very least destabilise the patina. Again it comes down to trial and error and realistically its better to trial this technique on a coin you have decided you don't want rather than the pick of the crop. Another variation is to increase the strength of the lemon juice working your way up to 100% lemon juice (not recommended) or using the dilute juice and soaking the coins for longer and longer periods till you find a correct dilution to clean your coins. Alternatively you can soak your coins in the lemon juice and then work on them with a brass brush, but keep in mind that if you don't remove the lemon juice from the surface quickly it could damage the coins and/or the patina. This still hasn't worked, or has partially worked but some hardcore encrustation still remains. The it may be time for the big guns - Electrolysis. This method can circumvent months of waiting and fiddling around slowly cleaning your coins, but you may also ruin a coin in a matter of seconds by stripping the patina off. Or worse, carelessly zapping yourself and doing some harm. Electrolysis kits can be purchased or made for a few dollars. If you're using your kit correctly your coins should be fizzing in the salted water and may take from a few seconds to minutes to finally see that detail! Try dipping the coin cautiously at first and then removing it and scrubbing with a toothbrush to see of the dirt comec off. If it doesn't work the first time, try again untill it does. These are instances where even electrolysis may not remove the encrustation and sometimes the frustration will get the better of you. When this happens you can try removing it with any number of objects, such as knives (be delicate!). If you haven't used an electrolysis kit before start on some coins you have determined to be low grade and see how long it takes to clean them. Again it comes down to trial and error and realistically its better to trial this technique on a coin you have decided you don't want rather than the pick of the crop. Trial and error is required for all of these methods and it's best to test them on your identified lower grade coins. Try not to strip the patina from the coins or damage it in any way. • Hydrogen Peroxide at 3% concentration in water and changed frequently - note this must be done in a very well ventilated area and away from small prying hands. Your coins are kept in this solution for short periods of time and this has been known to remove light encrustation. Experimental tests have been done with strengths as high as 30% with much success. • CRC/WD40/Oil based lubricant have been applied directly to the coin surface to remove dirt and sometimes patina. This combined with a toothbrush may be effective on stubborn coins but is not recommended. • Food acids, such as Baking Soda or Vinegar, can be applied in varying concentrations but remember to wash off the surface of the coins with distilled water before using a toothbrush/brass/silver brush to clean hardened deposits. • Baking your coins in the oven / Boiling your coins / Boiling and then baking, etc. For more details on these last two methods please read up before attempting at the two internet groups listed below. • A dremmel drill can be used to remove encrustation, but unless you have a very steady hand and a keen eye for detail this could well be one of the fastest ways to ruin your ancient coins. • Soap and water may be used provided the coins are rinsed at least twice afterwards with distilled water to remove any of the residues. The coins need to be dried to help preserve them and their patina. • Rock tumblers may be used with some good results. Some dealers use this method to mass clean their coins before resale. At all cost avoid using acids or anything containing acid on silvered coins. For all intensive purposes we are using the term "silvered" to describe a bronze coin with silver coating. 1. Apply a fairly soft toothbrush to the coin while submerging it in Liquid Soap, with no water added. Use enough Liquid Soap to only just submerge the whole coin. You still want to be able to find the coin in the liquid soap without having to "dive" in the bowl (or whatever container you've put it in) and get your whole hand or arm covered with soap! Scrub firmly but don't push too hard on the toothbrush. If you overdo it and remove the silver there's no way to go back and retry! 2. As the Liquid Soap gets mucky with the dirt from the coin, remove the coin and give it a rinsing bath in distilled water. 3. Repeat steps 1 and 2 as necessary, but don't overdo it -- Don't try to remove that last little piece of nagging dirt on the silvering at all cost or you'll most probably just end up ruining the entire coin. 4. Dry the coin gently with a paper tissue or similar. Simple methods such as lemon juice and a tooth brush generally suffice for non encrusted coins. Repeat as often as necessary but do not continue this method if you see your coins surface deteriorate - it may be an ancient fake and only has a silver surface (hence the term silvered). My coins are cleaned... So now what? If fortune smiles on you then you will want to identify your coins! Now you may have some clearly identifiable coins or you may have a whole heap of worn coins. The latter isn't necessarily a bad thing - an extremely worn coin of a rare emperor may fetch hundreds of dollars even by comparison with a coin that grades Extra Fine (EF). This will hopefully emphasise the need for you to go through your coins one by one and try and identify them all before becoming frustrated with defailed cleaning. The best advice I can offer is: if you don't have the patience to do this right away, put them to one side until you feel motivated! Are there any books which might help me identify my coins? There are many books from you can choose from, beginning with some relatively cheap introductory books through to books costing 1000's of dollars. David Van Meter's book "The Handbook of Roman Imperial Coins" is easily obtainable for around US$34 through eBay or many other online bookstores. It contains around 8000 Roman Imperial coins and stands apart from books at this end of the scale. Another book which is helpful, although it does not go into as much detail, is Zander Klawans "Handbook of Ancient Greek and Roman Coins" which usually retails for around US$14. For those of you with larger budgets there is the multi volume Roman Imperial Coins set which is extremely comprehensive although some of the descriptions of rarity are very outdated as the Eastern Roman Colonies open up and we see more coinage coming out of Syria, Jordan, Iraq and other such countries. There is also software available such as Moneta which for around 100$USA is more up to date than the RIC series and certainly take up less space! Are there any online sites to help me learn more about the best ways to clean my coins and identify them? Yes, definitely. Numis Treasures discusses innovative methods and procedures to clean ancient roman and Greek coins. You will have to join to be able to post, but unlike many online sites, your email address and it's privacy will be respected. Never fear asking a question you may think is "stupid" - the people in groups like this are often very willing to help you - and everyone starts off with limited knowledge. You can also choose to use the services of Wildwinds which is a very extensive online list of coins with pictures, descriptions and a search engine to decipher your coin inscriptions. A list of Roman emperors and encyclopaedic information can be found here.
Cameron Day |
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(Image B) 
