Ambrotypes

Ambrotypes were invented around 1850 by Frederick Scott Archer and then patented by James Ambrose Cutting in 1854. Ambrotypes began to rival the popular daguerreotypes of the time. Visually, they have less depth than a daguerreotypes, but they were easier and cheaper to create than daguerreotypes.

Ambrotypes are an alternative development method, to the photo paper we use today. At the time this was how photographs were developed displayed. They are a glass negative that appears positive because of a black backing placed behind the glass. The clear areas are actually the black areas of the photo and vise versa.

Ambrotypes are created through the wet plate collodion process. A glass plate has a thin layer of collodion on it and then it is dipped in a silver nitrate solution and then exposed to the picture subject while the plate is still wet, creating a negative on the glass surface.

Here is a site that explains the entire process and how to do it yourself.