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 Replies: 13 / Views: 1,286 |
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Pillar of the Community
Canada
5417 Posts |
So.... I bought a lot of 200 ancient coins and picked through them. Picked out about 50 that I liked and the others would be resold. Out of the 50, there were 4 silver and the rest are base-metal. Happy to say that olive oil has worked wonders as far as cleaning the bronze/copper coins. Out of the 4 silver, one of them was already fairly clean, so I decided to leave it alone.
Now, on the problem of the other 3. They seem to have a hard encrustation on both sides, which is of similar color and quality on all 3, so I'm assuming these were dug up in the same place. All three seem to be imperial denarii' and I've been trying for weeks now to try to get some results here. Olive oil and distilled water won't even budge even the slightest amount of the crud.
The "dirt" on the coins is dark red in color, so perhaps there is a high iron content that is causing this problem. I've heard that lemon juice works well with these but I'm afraid to try something with such a high acidity.
Can anyone suggest what would work best with these? Thanks. Edited by zxcccxz
04/03/2015 9:29 pm
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Pillar of the Community
United States
5155 Posts |
I would like to see pictures of the coin in question. Each coin should be addressed on a case by case basis, it might be worth it not to mess with it.
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Pillar of the Community
United States
4964 Posts |
yes, pictures would be good please.
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Moderator
 Australia
16829 Posts |
I have heard about "red deposits" on debased-silver coins being the toughest to remove. Unless they are particularly large or disfiguring, it's generally advised to leave such deposits alone.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Pillar of the Community
Spain
629 Posts |
Well, I need a good image to say...
I have used debased ammonia in several cases with good results, you must control the process all the time that last and every 5 minutes aprox. trying to scratch the deposit carefully with a wooden stick...
But I repeat, I must SEE.
:D
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Pillar of the Community
United Kingdom
4208 Posts |
An image is probably necessary here. If it is the dreaded red stuff, you also have the very dangerous option of smoothing - entirely mechanical removal, which I would only ever attempt in the fields where you can cut it flat.
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Pillar of the Community
 Canada
5417 Posts |
Here are the pics:    My issue is, the coins all seem to be high grade underneath the deposits and leaving them as they are is a waste IMO. Edited by zxcccxz
04/04/2015 4:04 pm
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Pillar of the Community
United States
3439 Posts |
Reasonably high grade. I can see a Geta as a young lad on the right and what looks to be a Septimius in the middle.
Silver coins of this period grade much like modern coins. Quite a few VF/EF examples of the family of Severus are available in silver denarius. The bronze issues are much harder to find and the grading in more lax. A decent As of Geta or Caracalla in F
Condition will cost over $100 while EF denarii of same can be found for 1/3 the price.
That said I have precious little experience will removing red stuff. It probably is quite hard and may need to be 'convinced' into leaving. But that may damage the coin.
I think you may need to do a long term soak in olive oil. Perhaps a year or more.
Whatever comes off comes off. If it won't ...... then leave it !
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Pillar of the Community
Spain
629 Posts |
The denarius on the left may be sumerged in an ammonia solution, after 5 minutes try to scrach the dirt carefully with a wooden stick or something soft enought to not damage the surface of the coin, repeat another 5 minutes and so on...
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Moderator
United States
23731 Posts |
I've had good results using lemon juice. Try diluting it at first and working your way up to a stronger solution.
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Pillar of the Community
United Kingdom
3626 Posts |
Olive oil is not my first choice, but I would use it here. Put them in separate tubs for a long term soak. You are going to be able to deal with the larger dark one first. I would leave that for a month, just giving the tub a shake when you pass it.
Personally, I would use a scalpel blade on that one. Applying just enough pressure to fracture the surface of the dirt without touching the surface of the coin. Remove what you can without using force. When it becomes more resistant, put the coin back into clean OO for another week or so, then repeat.
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Pillar of the Community
Canada
5417 Posts |
Appreciate the advice. I will first try soaking on olive oil for a few months while constantly shaking, as this will probably do the least amount of potential damage. If, after 6 months there are no results I will try lemon juice. I don't think I'll resort to ammonia, if rhey don't clean up, I'll resell them along with the other 150 coins.
I forgot to mentioned before though, these three were already soaked in olive oil for three months from mid-November to mid-february.
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Pillar of the Community
United States
4964 Posts |
I'm way out of my league here on cleaning here, looks like some serious stuff on there.
but i'd love to see the results of your efforts
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Pillar of the Community
United Kingdom
3626 Posts |
Use ammonia in preference to lemon juice first. Lemon juice can really affect debased silver coins.
Prior to picking, you could try warming the olive oil. Put coin and olive oil in a smaller container, put that container in a pan of water and heat. Just before it comes to the boil, turn down the heat. You don't want the oil to boil. Keep the water simmering and don't let the pan go try. Top up the water if necessary. Keep this going for several hours.
You can add a few drops of lemon juice, but before you do this you must be sure that the coins are made of good silver.
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Replies: 13 / Views: 1,286 |
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Posted 04/03/2015 11:10 pm
