Preservation of National Numismatic Collection

Posted on 3/3/2008

NGC designs custom holder to house the 200 most rare, unique and famous American coins in the Smithsonian's National Numismatic Collection.

The Smithsonian’s National Museum of American History today announced a pilot project to assess the use of protective coin holders for the National Numismatic Collection housed at the museum. The 200 most rare, unique and famous American coins in the collection will be placed into customized plastic holders that will allow greater access to coins while improving their protection.

This initial group of coins was chosen because they are the most frequently handled. The project is a collaboration between the museum, the Numismatic Guaranty Corporation and the Numismatic Conservation Services, which donated their services and developed the holders to meet museum specifications. NGC also provided the materials necessary to re-house the coins, along with two storage cabinets which will offer enhanced security for these numismatic treasures.

"We are pleased to be able to provide superb protection for these rare objects while at the same time extending access to the research community," said Brent D. Glass, museum director. "The coins are popular for scholarly study and now they can be handled safely."

"NGC is privileged to work with the museum to help solve a collections management challenge. We are honored to make the full breadth of our expertise and our services available to the NNC and the greater numismatic community," said Mark Salzberg, chairman of NGC.

David J. Camire, president of NCS, added "The focus that the museum has put on the long-term preservation of the NNC should be strongly commended. It’s a great privilege to commit our resources and energy to this important initiative."

The holder is made of inert mold-injected resin and the label, identifying the coin in it, is printed on acid-free paper. Its overall size is roughly 60 mm wide by 85 mm tall. It can accommodate coins up to 45 mm in diameter and nearly 5 mm thick. Coins are placed in pre-molded cores that are semi-rigid which is then encapsulated in a clear outer shell.

Traditionally, coins in museum collections are stored in open trays. However, they may be dropped or scratched when they are examined by staff or researchers. The exposed coins also may collect dust, fingerprints and other contaminants. Placing the coins in these protective holders allows researchers to view and handle them safely. The holders are not permanently sealed and staff is able to easily access the objects if necessary.

Prior to the re-housing effort, the Smithsonian conducted rigorous materials analysis and testing to establish the long-term safety of all of the components used in the manufacture of the holders. Results indicate that the holders will remain inert and stable for decades into the future. This finding provided the curatorial team with the information needed to move forward. Because of the emphasis on the long-term preservation of the collection, the pilot project also will include regular inspections of the re-housed coins.

Numismatic Guaranty Corporation of America certifies and authenticates rare coins, tokens, and medals. Numismatic Conservation Services is the sole professional service dedicated only to the conservation of numismatic objects. Both NGC and NCS are independent members of the Certified Collectibles Group, headquartered in Sarasota, Fla.

The museum’s National Numismatic Collection consists of more than 1.5 million objects, including coins, medals and paper currency, and preserves the role of money in economic history. Rare early American proof coins from the NNC will be on display in Baltimore, Md. in August 2008 at the American Numismatic Association’s World’s Fair of Money.

The National Museum of American History collects, preserves and displays American heritage in the areas of social, political, cultural, scientific and military history. Documenting the American experience from Colonial times to the present, the museum looks at growth and change in the United States. The museum is closed for major renovations and will re-open in fall 2008. For information about the museum, please visit or call Smithsonian Information at (202) 633-1000, (202) 633-5285 (TTY).

Released February 29, 2008, Smithsonian, National Museum of American History, Kenneth E. Behring Center. Contact (202) 633-1000 or visit for further information.

Encapsulation Project
James Hughes, Associate Curator of the National Numismatic Collection, presents a tray of coins to be encapsulated in the NGC re-closeable museum holder. David J. Camire, NCS President, inspects each coin prior to encapsulation, and Alex Nunez, NGC Encapsulation Manager, expertly places them in their new holders. Click image to enlarge
Encapsulation Project
David J. Camire (right), NCS President, inspects each coin prior to encapsulation. Alex Nunez (left), NGC Encapsulation Manager, expertly places them in their new holders. Scott Schechter (center), Certified Collectibles Group Director of Marketing, performs a final quality control examination of a newly encapsulated coin. Click image to enlarge.
Custom Safe
One of the two custom vaults designed to hold the encapsulated coins slowly fills up as the coins are encapsulated. On the top shelf are the unique 1849 $20 and 1854-S $20 Proof coins, while the second shelf holds two 1907 Ultra High Relief $20 gold pieces, and a 1907 High Relief $20 that President Teddy Roosevelt presented to his niece as a birthday gift. Click image to enlarge.
Encapsulated Coin
The NGC re-closeable museum holder houses an experimental $20 Ultra High Relief with the diameter of the $10 gold coin. This is one of two extant; both reside in the National Numismatic Collection. Click image to enlarge.

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