The Dorn-Severini Historic Photography Collection

The glass plate negatives are perhaps the most unique, and challenging, aspect of Dorn-Severini Historic Photography Collection. Here, our students have tried to explain, in laymen's terms, what glass plate negatives are and how they must be handled. Further reading is provided for those interested. 

Glass Plate Negatives: What Are They?

By Michael Mazzola

Before digital photos, before flexible photographic film, there were photographic plates. Plate photography worked by using two plates, a base, usually made of glass, and an emulsion sheet. The emulsion sheet was made of many different chemicals that changed over the years. Some common chemicals used were collodion and gelatin. The emulsion layer took in the light created by the image and captured it using light sensitive chemicals, usually silver nitrate. Photography was not instant and it took several minutes for the silver nitrate to capture all the light desired. A chemical reaction between the base and emulsion layer imprinted the image on the glass plate. This creates the negative. The glass plate negative is then taken into a dark room where the photographer saturates it in another chemical solution. Usually, the photographer places the glass plate on a piece of paper and lets it sit in the solution for an amount of time. When the process is done, the negative image is transformed into a real photographic image that can be reprinted. Glass plate negatives are the original product of early photographic processes. Glass plate negatives are how images were captured using light and then transformed to make printable photographs.


Glass Plate Negatives: How Should they be Stored?

By Jack McDonald

Glass plate negatives are very valuable resources that require extreme care and maintenance in order to be kept in their best condition.  It is extremely important that the proper storage techniques are used when storing glass plate negatives so that they are not damaged or broken.  When handling these negatives, most archivists agree that it is crucial to remember to wear latex gloves in order to prevent altering them in any way.  The glass plates should be stored individually.  If plates are stored together it can cause them to flake or even break.  Plates should be stored in high quality paper or plastic sleeves that were manufactured specifically for film storage.  Polyethylene and polypropylene are generally considered safe sleeves to store them in.  After being put in sleeves, plates should then be stored vertically in storage boxes.  Boxes should not be overfilled as glass plates are heavy and it might become difficult to transport boxes safely.  Plates should also be placed at the front and back of boxes in order to balance the weight and avoid any shifting of the plates.  If boxes are not completely full with plates extra padding should be added in the front and back of the boxes to avoid any movement from the plates.  It is recommended that boxes are not stacked but if it is absolutely necessary they should only be stacked two high.  Boxes containing glass plate negatives should also be labeled “fragile” to let anyone know to use caution when moving the boxes.  In order to avoid any damage to the plates, boxes should be stored in a cool, dry place. 


Glass Plate Negatives: Digitization

By Nicole Parylak

Glass plate negatives are very fragile and should be handled as little as possible. Scanning helps preserve the image, in case anything happens to the original, and make a copy that can be used by researchers. This is a very time consuming process, however. 


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