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 Replies: 15 / Views: 1,158 |
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New Member
Slovenia
28 Posts |
Any advice on how to proceed with sterling and base metal coins/medallions which were stored for decades in plastic cases with disintegrated foam inserts in them? In some cases the foam turned to dust and I was able to remove some of it by using manual dust blower (the one watchmakers/photographers use). In other cases the foam is still attached to coins/medallions. See the pics for reference. I have a limited/good experience with distilled water/acetone and can use them as well. All sourced from local lab supplies. What would be a recommended time for each conservation technique? Thanks!    |
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Pillar of the Community
United States
901 Posts |
Artemis, it seems that you're proceeding with caution, which is a good thing. Since they've been stored for decades, there is no great hurry.
Acetone would be my first choice. However, it seems that some of these medals are attached to ribbons (forgive me for not knowing the terminology). Acetone may adversely affect these fabrics.
Best wishes, and update us with your progress!
Inordinately fascinated by bits of metal with strange markings and figures
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New Member
Slovenia
28 Posts |
The ribbons can be detached and not all medals have them so no problem. I may try distilled water first and then pure acetone to dehydrate the surface. If the distilled water will not work then I may try the acetone method. However, I'm not sure for how long. Any suggestions?
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Moderator
United States
122612 Posts |
I would start with Acetone. I honestly do not expect water to do much. However, I have no experience removing foam.
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Bedrock of the Community
United States
11302 Posts |
I'd go with acetone, with an initial soak timed for 40-45 minutes. Adjust accordingly if further soaking is necessary.
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Pillar of the Community
United States
901 Posts |
Agreed - I don't think that water would do much more that rinse away chunks. Hopefully the acetone will work. If it doesn't work, the next step is trying more aggressive organic solvents. But proceed with great caution!!!
Inordinately fascinated by bits of metal with strange markings and figures
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Pillar of the Community
United States
8861 Posts |
A couple of things to keep in mind:
1. Many medals are coated with lacquer or another finish as part of their production process. Acetone will disturb or remove such coatings - many medals treated with acetone never look the same again. Also, once gone, the finishes can't be repaired unless the medal is completely refinished (not a simple task).
2. After years of close contact with the foam you have shown in your image, the surface of a coin or medal is often permanently etched. Even if the foam residue is removed, the piece will continue to show evidence of the contact. The etching varies in severity from piece to piece, but it's generally visible without magnification.
I would start with distilled water, and after a good soak (15+ minutes - depends on amount of foam residue), use a wet cotton swab to gently dislodge residue that doesn't rinse off when swirled in a water bath.
Good luck!
Collecting history one coin or medal at a time! (c) commems. All rights reserved.
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Moderator
United States
122612 Posts |
I rescind my previous opinion and defer to commems' greater experience with medals.  |
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New Member
Slovenia
28 Posts |
Good points, thank you. Some of the medallions are space flown so they are quite valuable. I believe the medallions produced by Fliteline may have the lacquer finish. They are otherwise in a great shape just a little dusty from the foam. Hopefully the distilled water will work...
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Pillar of the Community
United States
8861 Posts |
Quote:
Some of the medallions are space flown so they are quite valuable This may be true for the European market - I am unaware of current trends there - but it is not necessarily the case in the US. I have seen many "space flown" medals sell for modest prices here. I realize that they are often hyped by online sellers - and that some collectors are taken in by the hype - but many such relic medals can often be found at coin shows and local coin stores for very modest prices (at least here in the US). It's also important to understand that claims such as "space flown" only require that a nut, a small piece of wire or something similar from the space vehicle be added to the molten metal used to create the medal's planchet. The claim does not mean that metal from the vehicle constitutes the entire composition of the medal's planchet.
Collecting history one coin or medal at a time! (c) commems. All rights reserved.
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New Member
Slovenia
28 Posts |
True, those are so called flight awareness medallions. However, some of the medallions were directly purchased and flown by astronauts. They are well documented and serialized. Those are rare, should I send them to the NGC for professional conservation?
Edited by Artemis737
11/13/2022 4:13 pm
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New Member
Slovenia
28 Posts |
The old (late 60's early 70's) disintegrated foam insert (probably) contains PVC, right? The best course of action would be to safely remove the foam in order to conserve the medals, correct?
The sterling medals are not coated, only the base metal ones are most likely lacquered.
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Pillar of the Community
United States
4567 Posts |
Would, Denatured alcohol work here?
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Moderator
United States
122612 Posts |
Quote:
The old (late 60's early 70's) disintegrated foam insert (probably) contains PVC, right? I do not think so. First of all, PVC itself is not bad; damage to coins is caused by plasticizers used to make is soft and flexible. I am sure a chemist can elaborate or refute this, but I believe most foam materials are going to be okay. Certainly the foam inserts used for coin capsule and holders are safe. Foams are "soft and flexible" because they are aerated, so there is no need for harmful plasticizers. So even if they were made with PVC, I would not worry.
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New Member
Slovenia
28 Posts |
Thank you. I read a book about the medallions which mentions the old foam inserts and that they may contain PVC. The author is not a chemist though, just a collector. Interestingly, some foam inserts are intact, but the older ones (by maybe 1-4 years) turned either to dust or are starting to show effects of decaying (e.g. stretching, discoloration, crumbling). Therefore, all medals are stored in the saflips.
Edited by Artemis737
11/21/2022 3:53 pm
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Moderator
United States
122612 Posts |
I should have added... Bad or not, I would definitely want to separate the disintegrating foam from the medals for aesthetics alone. |
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Replies: 15 / Views: 1,158 |
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Posted 11/07/2022 2:00 pm
