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To Clean Or Not To Clean - This Is The Question


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Hello to All Members,

                                      We have been finding many pre-decimal New Zealand Coins. After washing off the dirt they are covered in a layer of patina, that dull brown stuff which we have been reading should not be removed for poor technique will devalue the coins worth. Toothbrushes, bristle brushes, chemical compounds and polishing cloths are a No-No, but they look so nice and shiny to a novice like me.  Also just to let you guys know that electrolysis is not the way to go that ate a few of my good coins.

      We have been reading  that valuable coins are "Best left to a Professional", so it can be done the proper way!  What do they use? How do they do it without depreciating the value of the coin? Is there a knowledgeable Coin Expert who is willing to divulge their secrets, not for me but for the sake of the coin? 

      Failing that, how should the coin be presented to a potential buyer or collector with this patina on it? Because it doesn't look very nice like this, underneath is a beautiful coin and I would like to get fair trade value for them. Will they appreciate our respect for the coin in this condition by leaving it this way?

      Some are very nice and valuable judging from coin evaluation sites and others not so much. How can I decide which coins to show? Even some pennies are very sought after and small silver ones which are a rarity. What do I do, What do I do? Hum.

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On 1/6/2019 at 7:14 PM, Lobo Lover said:

Hello to All Members,

                                      We have been finding many pre-decimal New Zealand Coins... etc...

Please don't take any of the following the wrong way.. I'm merely replying to what you ask the best I know:

It's hard enough trying to dispense non-destructive coin cleaning advice when all variables are known; impossible to do when none are known..

What does "pre-decimal" even mean..? You say NZ coins, but does that mean also found in NZ..? If so or otherwise, where found (meaning geographical location, not 'on the beach' or 'on land' -- I will assume land because you said 'washing off the dirt', but that doesn't tell me an actual where..)? What type of soil (meaning acidic / alkaline, not hot / mild..)? Of what are the coins made (percentage of each metal is helpful..)? Since NZ coins, are they double metal..? More than one denomination..? I could go on..

Almost never if not absolutely never do I consider much less describe substance or discoloration on the surface of any coin coming out of the ground as "patina.." Absolute best case one might get away with using 'toning'.. More than likely it's chemical / mineral coloration or damage..

I can't tell you how to present but pretty much fair trade value comes down to a question of rarity.. As far as anyone else appreciating your respect for the coin and its condition by leaving it alone goes the answer is neutral-at-best, but you'll definitely hear about even the most passive failed cleaning attempt -- soon to be followed with a much lower price offer, if indeed an offer at all..

When it comes to cleaning dug coins specifically, intent being numismatic sale, my advice is a distilled water soak, perhaps some gentle agitation to float away loosened dirts, clean cloth pat dry and that's it.. If you absolutely cannot leave a coin alone, my recommendation is sonic clean in distilled water, then pat dry.. However, do not be surprised if sonic cleaning removes some but not all of the debris / buildup / toning -- in which case you end up with a partially 'shiny' coin with a distinct line of demarcation between that and the non-removed substance(s).. What does one do then..? Does the coin look better or worse that way..?

 It is for the most part a combination of uncharted territory and a buyer's market when offering "found" / "dug" coinage in a numismatic environment, possible exception rarest-of-the-rare items.. Entrance, with coins of alteration, is at one's own risk..

Swamp

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I've always wondered myself what 'professional cleaning' even means.  I can say the same about 'professional restoration' of antiques and art.  It's not like all the professionals have some magic machine that will produce the same result.  It's also true that in most cases (probably all cases in coin cleaning) that after completion, some (most?) experts in that particular field will be able to tell that the cleaning has occurred.

My approach has been to do a minimum to be able to see a coin's date and mintmark.  I previously soaked in water with car wash soap (less caustic in general than dish soap) but since decided to leave out the soap, so now I just soak in water.  For many coins (especially silver coins) that's all it takes to get it looking nice.  Coins made with copper alloys, though, at a minimum still show discolartion and often scaling/growth which in some cases obscures the date and/or mintmark.  My next step is to use a fingernail to try and scrape off the crud (technical term ?).  However, that can leave permanent damage.  My rationalization is that if I can't see the date+MM then what good is it?  Short of being able to tell by the coins features that it's definitely valuable (I've never found anything like that) it's numismatically worthless until I know the date and MM, and I'm not going to pay someone to 'professionally clean' a coin just in the 1/1000 chance that it has value that I might lose with my fingernail scrape.  Having said all that, if I knew of a less invasive way of (inexpensively) determining the date+MM then I would switch to that.

Once I know the date+MM I can decide if the value potential is significant enough to halt and seek professional advice.  (Such a fortunate result hasn't happened yet in my case.)  But also, as of now, I'm still in limbo as to what my next steps are when the answer is "not valuable enough", and thus (see below) my current research.

Coincidentally, on a whim I just bought for $10 (and opened the package this AM, so no time to read it yet) a ~25 page book titled:  COIN/RELIC CLEANING and PRESERVATION by Robert E. Granville (copyright 1990). 

I also have another book titled Cleaning and Preservation of Coins and Medals by Gerhard Welter (published by Sanford J. Durst).  Originally written in 1976 in German, more recent printings include Paper Money Restoration and Preservation by James J. Curto.  I've read some of this (the part relevant to my finds) and have picked up some chemicals to start experimenting on coins of little/no value, but haven't proceeded to that next step.

So, if learned completely does the information in these books give (with practice) the expertise to be a 'professional' in the sense of the standard warnings?  Are the authors themselves even such experts?  I like to steer towards precise, repeatable endeavors and practices.  Cleaning of coins (and the acceptance of those efforts) are way more subjective than that, but AFAIK it's the best we have right now.

 

 

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I don’t worry about ruining the value of a $10 or $20 dime by polishing it up. I just want them to look nice. If my efforts make a $20 dime into a $15 dime that’s just too bad! :smile: If a coin is worth over $100 maybe I might start thinking about such things.

Some prior threads...

Question Regarding Cleaning Equipment After You Find The Coins And Relics

Cleaning Old Silver Beach Finds

How To Clean & Preserve Your Metal Detecting Finds

Cleaning Old Silver, Copper & Bronze Coins & Relics

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      Thanks' to all for your replies and great answers, I do understand where your coming from with your words of wisdom. I think I'll take Steve's route. I love my pretty shinny little coins and I can spend hours cleaning and polishing my worthless Pre-decimal and Post-decimal  (if that's a real word) N.Z. coins. I have one of each of these 1950's Half Crowns though the Far Diamond and the Near Diamond are near worthless I know . For now though I have my sights set on a much more interesting item, wait till your see my next post. This one is sure to catch someone's attention. I do hope we have some WW II historians here with us. Happy hunting. Paul.

1950-nz-half-crown-obverse2c-far-diamond-28r-brown29.jpg

1950-nz-half-crown-far-diamond.jpg

1950-nz-half-crown- near-diamond.jpg

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If your not worried about degrading value, a simple Pink Eraser is very easy on coins. Go very lightly on silver coins or it might shine them up a little more then you might want.

Bryan

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Can't argue with those results Cabin! I find my share of old, often semi valuable coins...I get the dirt off, that's it. Thing is, you can't go back once you do it. 

 

My buddy Ron ( California Relic Adventures) has plenty of incredible coins. He shines them up. I razzed him once, he said I find them, I like em shiny, I don't care what someone thinks. True enough!

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18 hours ago, deathray said:

My buddy Ron ( California Relic Adventures) has plenty of incredible coins. He shines them up. I razzed him once, he said I find them, I like em shiny, I don't care what someone thinks. True enough!

Yep I'll look them up first then if not worth anything they get cleaned...Cabin Fever has the best method for cleaning coins I've seen. His Indians are amazing looking. I wonder what kind of camera he is using to get those nice close ups? Inquiring minds want to know :biggrin:

strick

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3 hours ago, strick said:

Yep I'll look them up first then if not worth anything they get cleaned...Cabin Fever has the best method for cleaning coins I've seen. His Indians are amazing looking. I wonder what kind of camera he is using to get those nice close ups? Inquiring minds want to know :biggrin:

strick

I used my iPhone for the photos. I can’t remember on these particular photos but I either cropped them or put a magnifying glass in front of the lens for the close up. 

Not all coins turn out this nice of course as some coins just come out of the ground helpless and others need more then an eraser to clean up nicely.. I always start with an eraser on copper coins after I rinse the loose dirt off.  Some coins will be packed with fine dirt that won’t come off with the eraser.  With those I will boil a small amount of Hydrogen Peroxide in a glass jar in the microwave and drop them in for a short time. The longer you leave it in, the darker the coin will get, so I usually start off for maybe a minute. If your lucky the eraser will then easily remove the caked on dirt. If not it goes back in to the peroxide for a few minutes.

Here is a coin I used peroxide on. You can see it is dark brown and if you look closely on the rim at around 1:00 position you can see I went too hard with the eraser and it started to go through the patina.

It also looks like I used Peroxide on the 1897 in my previous post. The 1904 just an eraser.

I only use Peroxide for copper coins. Not Silver. 

Bryan

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On 1/13/2019 at 1:42 PM, Cabin Fever said:

If your not worried about degrading value, a simple Pink Eraser is very easy on coins. Go very lightly on silver coins or it might shine them up a little more then you might want.

Bryan

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44AA654A-6884-43A8-9C1A-2A912F01E57E.jpeg

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Thanks for posting in this thread, Cabin.. I was trying to find an old thread where we were talking about cleaning coins cos I wanted to credit the person (you, as it turns out) who mentioned erasers -- but couldn't find that post..

I have a lot of artist supplies, mainly photograph / negative dyes and pencils accumulated during years in the now mostly obsolete industry.. I also have many different types of erasers but not a large pink one, since those are the ones found on the end of most pencils..

During the previous thread I found your eraser solution interesting so deceided to give it a try on IHPs I'd taken as far as I could this side of ultrasonic, caustics and/or oil.. This is when I discovered I didn't have a large pink eraser in my arsenal and also discovered they'd just break off the end of pencils due to amount of pressure needed (I could have made it work using vice grips or hemostats, but having others to test saved it for a last attempt if necessary..)

Out of all the others, which included plastic, gum, vinyl, magic rub, kneedgummi, an unknown substance containing erasing fluid and a few others unidentified beyond 'eraser', the only one that worked, and worked quite well, is the PaperMate Union ink on one end pencil on the other end eraser (other name brands omitted intentionally..)

It took a lot of elbow grease, but I eventually got the one I worked on 98% clean and I could have gotten the remainder if I worked some more on those recessed areas.. The price one pays is yeah, they become really shiny.. But I've been letting it sit out, putting it in with change etc. etc. and it's toning back down kinda quickly..

I only tried this on the one copper.. I'm fairly certain the ink side would be damaging to 'silver' coins and the pencil side will leave "rings around the stars" while making the rest of those coins too shiny.. But I still have a bunch of other erasers to try, if I want to give other than copper a go..

One other thing I noticed: As easily as new "copper" coins scratch even with new soft cloths, old copper coins stand up to just about whatever you throw at them eraserwise.. I couldn't notice anything that stood out above what was already there..

Point being, between these two types of erasers ( EDIT: and the hydrogen peroxide ) a person can most likely do a durn good job at cleaning up other-than-numismatic-value copper coins..

Swamp 

EDIT: This references your first reply only..

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