Numismatic and History Discussions > Coin Photography, Conservation and Storage

Help with displaying coins - using pins and getting corrosion


Craig H3:

First time post, long time reader of the FORVM. A bit of background - I've been assembling a collection of each emperor beginning with Augustus and ending with Constantine XI for over twenty years. For many of these years I had them in cabinet drawers but recently moved so I had an opportunity to display them in my office.

I have around 200 coins each on a 10" x 10" square of neoprene foam that is covered by adhesive backed velvet. The panel sits on a book stand so it's slightly angled back for display. Each panel has 30 rulers - 5 x 6 with a total nine panels - 3 panels on 3 bookcase shelves. Each ruler is tacked to the panel using gold plated pins - two on the bottom of the coin and one at the top (I had used 4 pins in the past - which will be evident in the Vitellius photo).

The issue is that I have seen corrosion where the pin touches the coin on one in particular (Vitellius) and it was so bad I had to replace it and not sure the coin has much value. I also noticed a bit of discoloration on a Julian II as Caesar siliqua and repined it with a fresh pin. My assumption is two fold - these pins might not be well plated so there could be bare steel touching the coin. I'm no chemist but I don't think it's a good thing. Second, I only see this on coins that are 'sliver'. However, I think it's the composition of the silver that makes the coin susceptible to the corrosion. For example, I don't see this on any pre Caracalla silver denarii nor do I see it on any 3rd century silvered folles. No issues with gold or bronze coins.

So - I'm at a loss, I love how my coins are displayed - I can enjoy them any time I'm in my office, but need to find a safer way to tack them to the panel. I've looked for inert pins (plastic or coated plastic) and can't locate any. I know museums display coins like this all the time and they pin them so there must be a solution. Your help, advice and experience are greatly appreciated.


I'm not sure what material your pins are made from, but a quick Google search for "archival museum display supplies" brings up several sellers of pins.  All of the ones I looked at are made from stainless steel.  So I would assume that those might be safe(r) for displaying coins.


I have also seen museum displays which use pins that are either coated in plastic or have a plastic sleeve around them.

Of course, that brings in the issue of the plastic type and quality.  It also has to be archival.

As Craig said though finding pins from a museum supply store may be the best bet.

Please keep us updated on your research....


Craig H3:
Good advice from both of you. I called the ANS and spoke to a very helpful employee there named John. They use stainless steel pins that are bent at 90 degrees. He also mentioned the plastic sleeve and pointed me towards Benchmark supplies out of NJ It looks like it will be a good deal of work to cut, bend, and sleeve these pins, but it will be worth it in the long run!

Thanks again,

Ron C2:
if you use pins of a different metal than the coin itself, you will get what engineers call dissimilar metal galvanic corrosion.  (can you guess I'm a mechanical engineer yet?)

What you are seeing is the pin interacting with the non-noble metals in the coin flan.  Coins that are essentially pure silver of gold are pretty immune to this, but many imperial coins have some copper alloyed with the silver.  The copper reacts with metals in the pins (brass, steel, etc.) and something called selective phase corrosion occurs, where the copper will porously corrode right out of the flan fabric.

My recommendation is to not store your coins this way in future.


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