Digital Collections Spotlight #48: Storage of Slides

Posted January 17, 2024 in Digital Access

Digital Collections Spotlight #48: Storage of Slides

In recent months we have highlighted the magic lanterns and glass plate lantern slides in the holdings of the Moravian Church Archives, Bethlehem. As an extension of this we would like to share some information on how these and similar materials are preserved and stored in our collection and how changes in technology have impacted this [1].

In earlier posts [2] we have discussed the nature and history of lantern slides and in the image above you can see how we store these materials. Each lantern slide is visually inspected and if necessary carefully cleaned before being placed in a paper sleeve as seen to the left. The call number of each slide is written on its sleeve before the slide is inserted, this associates the slide with the corresponding entry in our online catalog. The sleeved lantern slides are then placed on their edge in suitably sized boxes, as can be seen to the right. This placement is used as if the slides were stored stacked horizontally the weight could potentially damage them. The boxes are then labeled to reflect their contents and location in the vault and can now be safely stored.

A similar process is used for 35 mm slides, which supplanted lantern slides and were commonly used from the 1950’s into the early 21st century. In contrast to lantern slides these consist of a piece of 35 mm film in a paper or metal holder, making them smaller and lighter then their glass predecessors. As you can see in the image above these slides are stored by placing them in storage sheets that have a separate sleeve for each slide. These sheets are then stored in a specialized box that also acts as a binder, labeled as with the lantern slide boxes, and stored in the vault. This approach helps maintain the condition of the slides while also making them easily viewed by staff or researchers.

In the present day, projection technology has largely transitioned to projectors or screens that display digital formats, which has required us to adopt a completely different approach for preservation and storage than described above. These digital images come in a wide range of formats, but we will typically use software to convert them to the TIFF format, as this format is widely used and known to be very stable over time. The resulting TIFF copy is then stored on two external hard drives, of which one is connected to a PC for staff use and the other is stored in the vault. These hard drives are checked once a year to confirm that the contents are still safe and the drives themselves will be replaced at regular intervals. A third copy of this material is also stored offsite via a cloud storage service and is regularly checked for accuracy by that provider. This is the same approach we have been using for the material in our holdings that we have digitized, including the lantern and 35mm slides we have digitized as discussed in the afore mentioned earlier posts, and ensures that in the event that one copy is corrupted or one of the hard drives damaged it can be restored from the other copies.

[1] For a broader overview we invite you to visit our exhibit, “The Archival Process: New Acquisitions at the Moravian Archives”, either in person during normal business hours through June 2024 or through the online version which can be found here.

[2] Digital Collections Spotlight #44: Magic Lanterns and Digital Collections Spotlight #46: Moravian Lantern Slides

Further References:

If you have photographs and slides of your own that you are interested in preserving, our primary sources for supplies are listed below along with an information page from the Library of Congress that offers guidance and additional resources.

“Care, Handling, and Storage of Photographs” Library of Congress. Accessed 1/12/2024

Gaylord Archival –

Hollinger Metal Edge –