Popular Post GB_Amateur Posted January 3, 2020 Popular Post Share Posted January 3, 2020 One of the most controversial topics in metal detecting and coin collecting is that of cleaning coins. A lot of this comes from failure to define terms, such as purpose of cleaning and what ‘cleaning’ really means. I’m starting this thread as much to educate myself as anything. As such it is a bit of ‘brainstorming’. I’m not an expert although as is often the case, many of the people who claim to be such aren’t either. “Reader beware” has never been more true than in the 21st Century internet / social media world and this post is no exception. Numismatics is the fancy word for coin collecting, and the topic of coin cleaning must include facts and opinions coming from that segment of activity and knowledge. Here is a list of some of the concepts/issues/concerns expressed there: 1) A coin’s patina is important. ‘Patina’ is the natural toning that comes with age. This idea is shared with antique collecting, as is the concern over refurbishing/restoring/refinishing of antiques in general. It is almost universally accepted in numismatics that coins that haven’t been cleaned are vastly superior to coins that exhibit signs of having been cleaned. Whether or not you consider this reasonable, it’s locked in and not going to change. 2) Most of modern numismatics, and particularly the area with the largest investment, is in uncirculated coins. A lot of the information among numistmatists on coin cleaning relates to uncirculated coins. 3) Although “beauty is in the eye of the beholder” is a general cliche’, coins do change hands and many/most methods of cleaning cannot be reversed. Much of coin collecting (hell, much of the world in general) is about value and (permanent) cleaning has ruined a lot of coins’ values over history – thus the reason for major concern amongst numistmatists on this subject. What does ‘ruin’ mean? Reducing its value by 75-90% isn't uncommon. 4) Most collected coins did not spend years in the ground. The issues we detectorists experience are rarely even considered by coin collectors. 5) Often the word ‘cleaning’ among numistmatists is confused with ‘conservation’. The latter is loosely defined as removing foreign matter that in the long term will damage a coin. ‘Cleaning’ is simply trying to improve the appearance of a coin. Conservation is accepted, if done properly, of course. Even the two major grading services offer conservation options. 6) Statements such as the most common -- “never clean coins” -- or even the less dogmatic “cleaning should be left to professionals” may be well intentioned, but are neither informative nor practical. Who are these ‘professionals’? I suspect if you went to a coin show/convention and did a survey you would get very few answers to this question, but rather be referred back to #1 (“never clean coins!”). Although so far it may seem that numismatists are Chicken Littles, there is a lot of validity to their concerns. It’s just that you need to go past the cliche’s to understand that. Let’s start with an analogy many of us are familiar with – cleaning eyeglasses. What’s the best way to do that? (“Never clean eyeglasses” isn’t an option!) Fortunately micro-fiber cloth is a fairly modern convenience, and that (with a mild cleaning solution) is the proper method. But how many of us have used paper towels, cotton cloths (such as handkerchiefs or shirt-tails), etc. to accomplish the task? I have, and the results are eye-opening (no pun intended). Permanent scratches result, at least for modern plastic lenses (and that includes polycarbonate lenses). Abrasives are a common cleaning medium. Sandpaper is a good example. Would you clean your eyeglasses with sandpaper? Well, fibers in paper and cloth are also abrasives. That also applies to cleaning of coins. The naked eye may not notice fine scratches but coin grading involves magnification and then the scratches look like river valleys. (OK, I exaggerate.) What seem like minor differences in coin grades can translate to huge differences in value. Scratches are one of the things that determine coin grades. A very common occurrence in metal detecting, if YouTube videos are any indication, is the immediate rubbing of a coin when retrieved from the ground. The sand grains, etc., in the attached soil are abrasives! If you want to identify a recovered coin in the field, then take along a small spray bottle and blast the coin with water. (BTW, I’m aware that some perceived experts have claimed that water damages a freshly retrieved coin. While always holding out the possibility that my logic is wrong, ask yourself this question: how many years has this coin been in the ground, free from contact with water?!!!! Even the driest desert gets rainfall occasionally.) The reality is that many coins coming from the ground, especially those which contain mostly copper, are not attractive and sometimes not even identifiable without aggressive cleaning. If you’ve read this far, hoping to get some good answers, you are going to be disappointed. I don’t have them, yet. There have been a few threads on detectorprospector.com with discussion of cleaning methods. I’m not going to repeat those, nor even link to them since they are scattered. What I am going to do this year (new year’s resolution) is to both read more deeply and experiment with cleaning methods. I already own one book on the subject and just ordered two more from Amazon. My workshop is being upgraded to, among other things, make it more conducive to simple chemical experimentation. I’ll report back with my findings. In the meantime, here's an interesting discussion among coin collectors on the subject. Also, a well chronicled experience with one of the coin certification services regarding coin cleaning/conservation. 11 1 Link to comment Share on other sites More sharing options...
kac Posted January 3, 2020 Share Posted January 3, 2020 I would like to know what methods the experts use and how they considered experts. From my own experience if the patina is too thing the coin is junk anyways as there is nothing left below. I have tried on clad different techniques to at the minimum to see what details are left below the crud and still keep the patina if that is in existence. I found that: Acetone works well on tar and pine pitch. Mild acids, pickling solutions are just too aggressive, including lemon juice etc. Soaking in olive oil for long periods of time doesn't seem to do anything. Even tried a 35 watt Co2 laser which burned the foreign matter into the surface of copper. (not reocommended) Reverse electrolysis tends to destroy coins unless the surface has no dirt masking it (not recommended) Baking soda and water will take majority of dirt off and gently when used with a soft electric toothbrush but just takes some time but will leave copper/copper alloys dull. Typically I have been using baking soda and water to just take the minimal amount off so I can read what I have. Lastly as a non numismatist I have my own 3 level coin grading system: A- Shiny looks new B- Readable looks used C- Looks like an electrical box slug Awesome post as usual, looking forward to your tests. 7 1 Link to comment Share on other sites More sharing options...
GB_Amateur Posted January 3, 2020 Author Share Posted January 3, 2020 58 minutes ago, kac said: Even tried a 35 watt Co2 laser which burned the foreign matter into the surface of copper. (not reocommended) Pardon my reaction, but that sounds like one of those "glad I didn't try that!" ? However, you show we have a lot of chances to experiment. Most of my coin finds aren't worth more than face value, and most of the remaining have bullion value only. I have found between 150 and 200 Wheat pennies and most are pretty unsightly. But I've also found a few Memorials with the same problems. Thus I'm going to do the expermintation on the Memorials and save the Wheats until I've found/perfected a method. Same goes with US nickels -- experiment with the trashiest late date Jeffersons before touching any decent date Jeffersons, let alone the Buffalo, Liberty (V-) and Shield varieties. As far as (90%) silver coins go, I only have a few which need work. It's mostly the water recoveries (and from what I've seen on this site, a few desert recoveries) that show problems with US silver coins. But I'll be willing to experiment if someone wants to send me one or two. (I'll return them, if there's anything left when I'm done in Dr. Frankenstein's lab. ?) 3 Link to comment Share on other sites More sharing options...
Steve Herschbach Posted January 3, 2020 Share Posted January 3, 2020 Great post. Here are those prior cleaning and selling threads. I love my tag system! 8 Link to comment Share on other sites More sharing options...
coinhunterseth Posted January 3, 2020 Share Posted January 3, 2020 I've ruined ( removed the detail) from a good many old copper coins just by using water and a toothbrush, I learned not to use water the hard way. I've found that the way to keep the most detail is dry cleaning with a toothbrush and toothpick to remove the dirt. Wheats I just hit with a brass bristled brush because they aren't going to be worth much, and I just want them to look decent. Silver I just rinse off with water. 3 Link to comment Share on other sites More sharing options...
kac Posted January 3, 2020 Share Posted January 3, 2020 If you have naptha (rubber mold solvent/rubber cement thinner), it will do ok on copper to take some the dirt off without changing the color. Goof-off is nasty and think it is similar to the dangerous MEK used in counter top laminates and acetone is the safer alternative which also isn't very nice. For many years I had used acetone and it does quite a bit of nerve damage to your hands so snag some poly gloves like the ones used in hair salons. An ultrasonic cleaner can do ok to take some the small dirt off without abrasives but avoid detergents as they can cause more patina on the coins. I had used it with a uv ink cleaner called yellow magic but you need to rinse really well after. I just leave the patina on the coins now, butchered a few slugs thinking I could recover what is underneath but found for the most part the patina is in better shape than the badly corroded copper below it so removing that you remove the detail. For my clad I have put about 30lbs or so through my vibratory tumbler in dry fine walnut shell which took the dirt off really well but took a few hours. Figured the bank might not appreciate me tossing muddy coins through their machines if I decide to cash them in LOL. I wouldnt use the tumbler on the oldies though because it is abrasive. I should contact my uncle on this as he is a retired chemist and one point specialized in cleaners. Maybe he has a few tips. 2 Link to comment Share on other sites More sharing options...
GB_Amateur Posted January 3, 2020 Author Share Posted January 3, 2020 10 minutes ago, kac said: If you have naptha (rubber mold solvent/rubber cement thinner)... Naptha can be bought at hardware stores. It's similar to the hydrocarbons in gasoline, but gasoline also has other additives as most know. Hexane is a purer form but otherwise similar. If your remember, or even still have, cigarette ligher fuel (Ronsonol in the blue and yellow small rectangular can is a common brand), that is also just naptha. So is 'White gas' or Coleman Lantern fuel. 2 Link to comment Share on other sites More sharing options...
Joe D. Posted January 4, 2020 Share Posted January 4, 2020 I like to put them on the railroad tracks!! Or just wack them hard several times with a plain ol' 16 oz claw hammer with a smooth face! Really makes them coins shine! (Gotcha!!)? I usually put my finds in a pouch until i get home to clean! No rubbing in the field for the most part! Dry land coins usually get a gross decon rinse, than anything decent gets a heated 3% peroxide bath till fairly clean, with toothpick cleaning and repeat, if necessary! Salt water/beach coins same gross decon, than heated white vinegar bath! Toothpick, repeat if necessary! **Copper, clad, and silver get seperate baths! **I'm not a fan of muriatic acid due to its hazardous fumes (lungs), and tissue damage (eyes, and skin) It's not worth the risk!!! ******Keeping in mind that these are detected coins from my particular area, and generally are not very old or valuable! ******And once a year i feed them into a coinstar machine to cash them in! The machine spits out the coins it doesn't like! ?? With 1715 wreck coins, and oldies being the exceptions! Of course!!? Link to comment Share on other sites More sharing options...
Gerry in Idaho Posted January 4, 2020 Share Posted January 4, 2020 I think the cleaning of a coin is subject to its rarity and or value. I've personally (when I was younger) removed great detail of patina from a few Large Cents and 1 Flying Eagle. All I used was water and a soft toothbrush. So now for some of my coppers that I really like, it is a soft dry toothbrush and toothpick, as Kac does. I've dug thousands of wheat backs and most are common dates/mint marks. I toss then in a tumbler with fish aquarium gravel, a little water, squirt of Dawn dish soak and let them run 15 to 20 minutes. All I am doing is knocking the crud and dirt off them. Silver, When I was young they were tossed into the tumbler too and boy do they shine. Problem is some silvers are semi and key dates with low mintages. Those need to pampered and soaking in water with a light rinse is all I do. Common Roos, Merc's and Washington quarters are soaked and brushed with toothbrush, but I quit tumbling them, as the shine, in my opinion is not recommended. Nickels, Those pesky dark stained, sometimes purple or red, brown, even black on occasion. If they are common dates, I toss them in the tumbler. Semi dates ones get the water and soft tooth brush. I'll use an eraser on them to add highlights, but I assure you there is abrasive marks left from the eraser. At least the common Buff or V now looks better with a highlight, but that is my coin so I am not worried of value. My 1913-S Barber Quarter (Key date) was dug in Nevada and as most of my 100+ yrs old silvers coming from the desert with high alkali, they come out of the dirt with a crustry gray coating. I have not done anything with it, other than water and tap dry. The actual condition of the coin is F-12 with detail, but the other blemishes and clap on it kills the value and most certainly drops condition. I have yet to decide (and keep going back and forth) on if I should get it professionally cleaned and as stated what makes one a Professional? I guess it depends on the person and what you plan on doing with it. Myself for this coin. If PCSG says cleaning will drastically reduce the value, then I'll probably leave it as is. If they say "after cleaning it will have detail of F-12" and look much better, but will be labeled as "Environmental Damage", and the value will drop a little, then I'll probably get it cleaned. If the value drops 50% or more, I might as well leave it as is. Who knows, but right now it looks like crap to me. 4 Link to comment Share on other sites More sharing options...
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