Putting It All Together: The Assembly and Rehousing of Glass Plate Negatives

I am thrilled to be participating in a pre-program conservation internship with the Smithsonian Center for Archives Conservation at the Smithsonian Institution Archives, as it has allowed me to gain invaluable hands-on experience with book and paper objects. As my internship has progressed through the summer months, I've also been presented with the opportunity to treat a variety of other objects and collections. One collection that caught my attention due to the interesting preservation challenges it posed were 8x10 inch glass plate negatives of cacti (Opuntia genus) by Dr. David Griffiths. Plus I have a degree in photography, so to have a hands-on experience with something that has been purely theorectical was very exciting. 

There are approximately 2,300 glass negatives in the David Griffiths Collection, Record Unit 7370, created between 1900 and 1916. Since 1916, the negatives have been housed in five different locations both inside and outside of the Smithsonian Institution. In 1981, it was discovered that a number of negatives broke beyond printability while in storage. The broken negatives were temporarily stored in paper envelopes until recently, when new rehousing procedures were initiated.

The goal for rehousing these glass negatives is to stabilize the object and ensure further damage to the materials is prevented. The glass fragments must be easily removable from its new housing (a storage container) so that future research and study of the negatives themselves and/or their subject matter can be safely performed.

The first step to rehousing the negatives is to carefully remove all glass fragments from their envelope.

Broken glass negative edges are very sharp and can cause cuts when handled. This not only affects conservators, but can also cause harm to the emulsion layer (a very thin layer of chemicals and gel) on the negatives. With the aid of a light box, the fragments are arranged in proper order onto a sheet of Mylar within a rigid cardboard frame.

This process is like putting together a jigsaw puzzle. The Mylar sheet makes possible the transfer of the assembled negative to a scanner bed for digital documentation. Since some negatives contain dozens of fragments, they cannot be printed via traditional means in a darkroom. Therefore, a high-resolution digital image will document the positive image (the image we are used to seeing) of the negative.

After the scan is complete, the negative is transferred from the Mylar onto a flat, custom-made, sink mat. The sink- mat is constructed from flat acid-free cardboard and creates a 'pen' around the image to contain it. Instead of attaching the pieces together with an adhesive, acid-free cardboard "bumpers" were placed along the broken edges to keep the glass fragments from rubbing together. This prevents the potential for further chipping and breakage.

After the rehousing is complete, the object label is attached to a cardboard portion of the mount and the negatives are flat-stacked into appropriate boxes for permanent storage at the Smithsonian Institution Archives.

Although my internship has centered around paper objects, working with these photographic materials has been an added bonus. Hopefully their successful stabilization and rehousing means more researchers will be able to enjoy and glean information from these images.

Related Resources

• Walking on Broken Glass, The Bigger Picture blog, Smithsonian Institution Archives
• The Preservation of Glass Plate Negatives, by Greta Bahnemann, 2012
• How Do I House Glass Plate Negatives?, by Sarah S. Wagner, Senior Photograph Conservator and Miranda Martin, National Preservation program Officer, Preservation Programs, National Archives and Records Administration
• Griffiths' "Cacti Glass Negatives" collection, by Vicki A. Funk and C. Tuccinardi

Related Collections

• Record Unit 7370 - David Griffiths Collection, circa 1900-1920, Smithsonian Institution Archives