Processing the Past: Glass Plate Negatives from Our Collection

Glass plate negatives are an essential part of historical and cultural documentation. The survival of these negatives is remarkable not only because of the fragility of the glass itself, but also due to the common practice of “plate recycling” during the 19th century. “Plate recycling” was the act of scraping off the emulsion of old and unwanted negatives and applying new emulsion. Manufactures purchased many of these scraped plates because they were easy to reuse being that they were already cut to standard sizes.

Throughout the course of this exhibit, The Cayuga Museum is making an effort to preserve thousands of glass plate negatives. Over time and improper storage, some of our collection has suffered deterioration.

However, due to advances in technology we are digitizing the plates with scanners that are able to capture details and rediscovering images that were left unseen for decades.

 


 

History of Glass Plate Photography

Developed in 1851, wet collodin glass plate negatives led to the demise of former photographic processes: daguerreotype, ambrotype, and calotype negatives. Wet collodin glass plate negatives allowed for sharper images with less exposure time.

To create a wet collodin glass plate negatives the photographer would sensitize his glass plate with a coat of collodin, a sticky substance that allowed light-sensitive silver salts adhere to it. The plates had to be sensitized immediately before exposure and shortly after before it could dry. This meant that the photographer had to carry all of his equipment and chemicals into the field.

Techniques to slow the drying time of collodin were discovered to allow the photographer to have negatives prepared before a shoot, however the use of these “dry plates” required a longer exposure time with inconsistent results. Most photographers continued to use the wet collodin glass plates because of the inconsistencies, which hampered commercial efforts to produce and market the plates.

Wet collodin glass plate negatives revolutionized photography in the second half of the 19th century. This process remained popular until 1880 when the use of gelatin on dry glass plate negatives emerged.

Gelatin dry glass plate negatives were introduced in 1871 as an advancement to the wet collodin glass plate negatives. Gelatin dry glass plate negatives were prepared by coating glass plates with gelatin and light sensitive salts. These negatives were ten times more sensitive than wet collodin glass plates.

Another important aspect of gelatin dry plate glass negatives is that they were made well in advance of their use. This meant that for the first time negatives could be manufactured rather than prepared by the photographer. Eliminating the need for the photographer to bring all of his chemicals and equipment into the field. The first gelatin dry glass plates were commercially manufactured in 1875.

These manufactured plates could be stored for long periods of time before being developed. In addition, the gelatin dry glass plates minimized the skills needed to mix hazardous photographic chemicals. For these reasons, manufactured gelatin dry glass plate negatives lead to the growth of armature photography in the 1880’s.

Gelatin dry glass plate negatives remained the preferred process until 1925 when it was surpassed in ease and popularity by gelatin on nitrocellulose sheet film.

 


We began this project by scanning the contents of unmarked boxes, and what we would find was completely unknown. We have no record of who the photographer was or who the people in the images are.  Many of these plates were stored improperly, which has taken its toll on quite a few.

 

 

 

 

 

 

 

 

 

This plate was damaged, and a majority of the image was lost.

 

 

 This plate was stored in the same box, but the image is significantly clearer when scanned.