| Author |
 Replies: 8 / Views: 4,619 |
|
|
Valued Member
United States
459 Posts |
I would appreciate any and all opinions, experiences, advice, or information regarding the removal PVC from early US silver coins.
Thanks
|
|
|
|
Moderator
 United States
23522 Posts |
Standard, full-strength acetone, as sold at Home Depot or other places. 1 each shot glass, small enough to support the coin by the rim yet large enough to get liquid above and below the coin. Coin first, then pour the acetone so the coin is covered completely. Cover the glass with either another glass or a glass plate to forestall evaporation.
Gasoline is kinda volatile. Acetone is EXTREMELY volatile. This stuff will burn your house down immediately if you let it get near an open flame. The fumes will give you flashbacks to the 60's, even if you weren't alive then. You gave been warned.
Change the solution after 24 hours, or sooner if it becomes cloudy. Repeat thus for the first three days. Rinse the glass and the coin with distilled water each time to remove any stuff pulled from the coin and clinging to the glass.
If any PVC still clings to the coin, leave it in acetone for a week or more. A silver coin won't care how long - acetone will not harm it in any way regardless of the length of the soak. Just be careful to monitor evaporation.
|
|
Pillar of the Community
United States
1203 Posts |
Short of having a professional do it for you, the only method that I would recommend is the one give by SuperDave. It has proven to work and usually don't cause more trouble than it cures. Just be careful with handling each coin and take your time.  |
|
Bedrock of the Community
United States
20753 Posts |
What SuperDave said. EXCEPT for one small thing. How do you know what the contamination on the coin(s) are? What makes you think it is PVC? Be carefull here. True about Acetone. However, prior to using Acetone from any place that carries it in a can, do this. Pour some in a very clean glass dish. Allow it to evaporate. If there is any residue, such as a white powder, discard that Acetone. The reason is Acetone is extreamely good as a solvent and the inside of the can, although treated, may become disolved in the Acetone due to excessive shelf life. For delicate treatments with Acetone it is always better to test it first. If the Acetone contains a disolate from the inside of the can it may do more damage to your coin than what you think is PVC. For sensitive situations Acetone is best used from a chem supply organization in a glass container. However, the Acetone from most stores is fairly usable since it is used sufficiently enough by people so that the shelf time is minimal. But to play safe, test it.
Now as for PVC. Discribe what you think is PVC. PVC is a fairly stable plastic substance that will not melt until 212degrees due to it being a covalent organic compound. It is a poymer consisting of H, C and Cl. C4H6Cl2. To make it softer and flexible usually Phthalates are added the compound. These do leak out over a period of time and attack substances near them. After a decent period of time this is no longer possible due to very little left. The term PVC is used by some as frequently as Vertigris.
Again, please discribe what you think is PVC. You may have a contaminate on the coins that would be best left alone. Many contaminates of Silver have adheared to the silver as a compound and removing it will take some of the silver with it.
|
|
Moderator
United States
23522 Posts |
To make one small elaboration on Carl's excellent clarification of my initial post (wow, talk about corporate-speak  ), it's the phthalates that attack the coin, not the PVC. Good point about testing the acetone, Carl. I have to add that to my Standard Acetone Blurb. |
|
Pillar of the Community
United States
974 Posts |
Awesome advise...I have my test coin ready and to Home Depot I go! Thanks All!
|
|
Valued Member
 United States
459 Posts |
Carl,
From one chemist to another, thanks for the elaboration.
Nelrak,
I hope this info helps and good luck.
|
|
Pillar of the Community
United States
2177 Posts |
My thanks also for all this detailed information.
|
|
Bedrock of the Community
United States
20753 Posts |
Always remember that all cans for all products are mass produced and the canning process is not infalable. The coating process can and does occationally fail to be very precise regardless of the eventual solution to be used on the inside. Ever notice a can of beer or pop that has an unusual taste that you thought was just you? At the joints of the cans on the insides is the poorest place for perfection in coatings. In food processes the coatings are never made of dangerous products but with chemicals like Acetone, Alcohols, paint thinners those coating on the inside of the can can slowly be disolved into the chemical inside. The inside of all cans are coated with a substance or the metal of the can would be chemically reative with some substances and become useless. If using any chemical from a can, test it if possible for such purities.
An old story of chemical purities was I read somewhere that many, many years ago a chemist made what he thought was the purest water in the world and incapulated it in a pure, clean glass container. After many years the water turned cloudy. The reason. Even glass can and does dissolve in water over time since it is only a Silicon Dioxide product.
|
| |
Replies: 8 / Views: 4,619 |
|
Posted 06/08/2007 7:21 pm
