I am now dealing with coins that have verdigris on them (and its not cost effective to send them to NCS for the most part) I have heard of biox and baking soda and verdigone as the three methods that can be used to get rid of Verdigris. Which method is the best please list your past experiences and any new developments in this field. thanks.
Electrolysis works great. You don't need a car battery or anything either. Just a small AC/DC converter, and some simple supplies. This method will work wonders on copper, but you must be careful to not apply too big of a power source. Too much current (amps) will pockmark your coins. I usually find an old cell phone charger or something 12 - 18 Vdc and less than 1amp output(400-800 mA). You basically just attach one wire to something conductive, and the other end to the coin, make sure they are not touching, and dunk them in saltwater. If the coin bubbles you have the wires hooked up right. Too much salt will usually cause the AC/DC converter to sense a short, and many will shut off. You have to add a little salt at a time to make sure you have resistance in the water, otherwise electrolysis will not take place. I think this is great for copper coins with heavy oxidation. The oxidized copper will literally just fall off. Be aware this process does remove metal from the surface of the coin.... It is basically the same process as electroplating (in reverse).
Just cut off the end and separate the wires and you're in business. How resourceful we are thesedays! As kids we used to have to wire-up 9v. batteries...what a pain!
Electrolysis will take off the verdigris - it will also take off any patina. I know from cleaning a few ancient coppers that electrolysis is held back as an absolute last resort. I can give you Bob Grellman's recommendations for cleaning early coppers. I have tried it and the coins come out absolutely gorgeous. First, a few drops of xylene (maybe called xylol also - available at most paint supply stores) and a nylon artist's brush. Just wet the face of the coin and tap with the brush until all the junk has loosened, then rinse with distilled water. Look in the crevices to make sure everything is gone. You can get really stubborn deposits with a toothpick and magnification if needed. Then brush a coat of Coin Care or Blue Ribbon cleaner onto the coin and brush it back off with a clean, soft brush like a jeweler's brush. The Coin Care/Blue Ribbon leaves a very thin protective coat on the coin, but this process does not alter the appearance of the patina of the coin.
I would say don't clean them........ However if you must practice less valuable one first. http://reviews.ebay.co.uk/HOW-TO-RE...-FROM-COPPER-COINS_W0QQugidZ10000000001234515 http://www.ehow.com/tips_13442.html http://www.coinworld.com/news/062507/BW_0625.asp http://groups.yahoo.com/group/Uncleanedcoins/message/28855 http://newsgroups.derkeiler.com/Archive/Rec/rec.collecting.coins/2007-03/msg02141.html http://www.colincooke.com/forum/comments.php?DiscussionID=21 http://metaldetectingworld.com/cleaning_coin_p17_copper.shtml http://coins.about.com/od/caringforcoins/ht/cleancoins.htm http://www.mycoincollecting.com/collecting/cleaning-coins.html http://www.coingalaxy.com/coininfo/help.html
Verdigris = Copper Acetate.... Copper(II) acetate is soluble in alcohol and water and slightly soluble in ether and glycerol. It melts at 115 °C and decomposes at 240 °C. It can be prepared by reacting copper(II) oxide, CuO, or copper(II) carbonate, CuCO3, with acetic acid, CH3COOH . It is used industrially as a fungicide, a catalyst for organic reactions, and in dyeing (The Merck Index , Ninth Ed., 1976).
Biox will take it off...it just requires a Q-tip for you to apply to the effected area, a small wait time and then a distilled water bath...it works very well and doesnt remove patina... you can buy some at http://www.dirtyoldcoins.com/shop/supplies/index.html This is what many museums use to fight verdigris...In fact I learned about it as it was in a PDF that lists supplies a museum uses to treat this. Of course if you clean a coin dont you know it will lose any value it had...
why would you say this? Instead of telling a person who has coins that obviously need attention NOT to clean them...just help them do it right...there is no reason to tell a person not to clean a coin unless the coin cannot be helped or improved by a PROPER cleaning. The only reason a cleaning would hurt a coin would be if it isnt done right and it cant be done right if people simply tell those asking for help not to clean coins (or worse pay someone else to do it when one can do it onesself easily in most cases). I would love to see people stop using this knee-jerk response to people asking for help..its not an over all bad thing to clean coins, its a case by case basis so 'dont clean a coin' is not a good answer in many cases but it is used by default by many. Just my quick 2 cents on that...not trying to be a jerk, just a pet peeve.
Biox may be great for ancients, but in my experience it will turn modern copper coins a dull pink. Be very careful if you decide to use it, and do some testing first.
I agree...... All the bigwigs do it, and for good reason. There is a right way and a wrong way. People need to distinguish the difference between conservation and wire brushes. There is obviously a chasm between the two, but many people assume the worst right away. Then the argument will be made that "usually" people do the wrong thing. IMO that is due to the fact that conservation can be a very good thing, and those who are skilled do not want to give away their secrets. I would like to see a book come out of NCS experience for example... fat chance.
I know, these people WANT peoples first response to be 'dont clean a coin' so they will think they just cant do it and will need to pay someone else. When it truth, from wha tI have read, much of what they use is easily available to all and what they do is not rocket science...its not that hard to do. I have found some interesting stuff online from museums that detail some of their proceedures when it comes to cleaning metal for conservation...that is where I learned about biox...if used right it will not damage the coin as it contains no acid...I have used it with good results on an austrian coin that had verdigris with no discoloration and no harm to the toning.
No offense taken... I have cleaned a few coins in my day. If a coin is deteriorating due to bronze disease then I probably would clean it, unless it was valuable. In that case I would take it to an expert as I am far from one. Sometimes cleaning can strip the natural patinia of a coin especially if it is done improperly. I do know that a coin cleaned to the point where any of the major grading services detect the cleaning, It will be rejected or slabbed with cleaning comments as the case with ANACS. The bottom line is cleaning a coin decreases it value.
I would say an improperly cleaned coin decreases its value...if a properly cleaned coins value is decreased, it is only because people have an irrational aversion to cleaning of any kind. In many cases I would think cleaning a coin could increase the value as it increases eye appeal of a corroded or unattractively dirty coin. I know that is just my own opinion but I have seen coins that were just plain filthy but in great condition under the filth, a good cleaning brought out all the great detail but did not strip the coin of its natural toning...it was much more attractive and thus I would think it would be more likely to fetch a better price...and the way it was cleaned, I would challenge anyone to conclusively point to anything that shows evidence of cleaning.
Yeah, not recommended for children under 12, so I guess that rules me out. So what do you recommend we do? I mean I trust you don't just dig them up and throw them in a box.
