| Author |
 Replies: 13 / Views: 1,504 |
|
|
Moderator
 United States
16679 Posts |
I'm wondering how I can get this off. It is a thicker, spot encrustation. I tried verdi-care, nothing. The coin is already a problem coin, metal detector find, so I'm apt to experiment with it. I thought about a sharp toothpick and trying to "flick" it off. I know there will probably be a pit there afterwards...thoughts?  swcoin.ecrater.com
|
|
|
|
Pillar of the Community
Australia
4411 Posts |
If you don't care for it too much I would be trying to pick it away with a lot of patience and care. Be prepared to screw it up beyond any collectable grade though.
|
|
Bedrock of the Community
Australia
21786 Posts |
I think that this amount of verdigris is too heavy for Verdi-care.
From pictures in different threads I have seen on this forum, Verdicare has yielded excellent results, but not with verdigris this heavy.
Some ancient coin guys try immersion over a long period (months) in olive oil for their uncleaned bronze coin purchases. That approach may work here.
Currently, I have an ancient bronze in oilve oil with just abount the same amount of verdigris as your coin. I will examine it in a few months.
Most bronze ancients have to be cleaned after being dug up. A lot of them would be unidentifiable unless they ARE cleaned.
After I think it has been immersed for long enough, I will attempt to pick the verdigris off with a wooden orange stick. I am expecting to find damage underneath the verdigris, something like the way rust attacks steel.
|
|
Moderator
 United States
16679 Posts |
sel, what do you use to get the olive oil off?
swcoin.ecrater.com
|
|
Bedrock of the Community
Australia
21786 Posts |
This my first attempt with olive oil, but I can't see why any of the organic solvents that are effective with olive oil cannot be used. I have access to most.
Initially, I can't see why soap and water cannot be used, but for final cleaning, good 'ole acteone seems to be an old favorite here amongst those in the CCF, and is safe with coins.
|
|
Rest in Peace
United States
9104 Posts |
|
|
Moderator
United States
16679 Posts |
Thanks guys. I was thinking of acetone :)
Now, the 1878 is going to take an olive oil bath for 6 months.
I will share the results.
swcoin.ecrater.com
|
|
Bedrock of the Community
United States
20753 Posts |
I would start with very warm distilled water. Not boiling but very warm. Allow to soak in that for a while. Nothing to loose and a lot safer for the coin.
|
|
Moderator
United States
16679 Posts |
I'll try that first carl ;)
swcoin.ecrater.com
|
|
Bedrock of the Community
United States
10045 Posts |
I think this is a mineral replacement of bronze?  I have deposits like this on ancient coins. Even if you removed it, there would probably be a cavity left. |
|
Pillar of the Community
United States
526 Posts |
Olive Oil has a high concentration of natual acid in it. Becareful using it and flip the coin often as the bottom of the coin does not get the same concentration as the top. Change the olive oil every three or four days and examine the coin. Rinse well with an acetone bath when done or the acid will continue to deteriate the coin over time.
|
|
Bedrock of the Community
United States
20753 Posts |
Quote:
I think this is a mineral replacement of bronze? I have deposits like this on ancient coins.
Even if you removed it, there would probably be a cavity left. Of course and that should be expected. Still better than a large lump of Green Stuff. More than likely it is a Sulfur Acid type of attack and the results may be Copper Sulfate which is soluable in water. That is why I suggested Distilled water first. It is the least distructive substance for such attempts to get rid of any contaminations. Also, as noted Olive Oil is acidic and it doesn't care if front of back, it attacks both sides equally. |
|
Bedrock of the Community
United States
10045 Posts |
Quote:
Still better than a large lump of Green Stuff. More than likely it is a Sulfur Acid type of attack and the results may be Copper Sulfate which is soluable in water.  A DW soak cannot hurt, although sometimes copper can tone a little--based on what I've seen. I won't claim to understand the chemistry of buried bronze coins--only what I've seen on my ancients.  |
|
Bedrock of the Community
Australia
21786 Posts |
Copper sulphate is soluble in water, unlike verdigris. Copper sulphate, which is quite poisonous, will easily wash off with water, verdigris will, and is extremely difficult to remove.
Verdigris is a water INsoluble complex and variable double salt of copper hydroxy carbonate. A number of chemicals are capable of attacking it, but there is also equal risk to the coin.
That is why the very slow rate of reaction which immersion in oilve oil allows, is used by those who recover buried ancient coins.
Edited by sel_69l
02/20/2012 06:51 am
|
| |
Replies: 13 / Views: 1,504 |
|
Posted 02/18/2012 9:13 pm
