Basically, all black and white photographs consist of the reactions of silver to light, and in modern photography to chemicals. The first photographs had no negatives and thus could not be easily reproduced - the negatives were part of the actual image. The first practical photographic process1 was invented by Frenchman Louis Daguerre in 1839 and resulted in the daguerreotype. After being sensitized by chemicals, the plate was exposed, the image developed by mercury vapor and fixed permanently by other chemicals.4 The extremely delicate image, which resembles a mirror and can appear as a negative or positive, was placed in a hinged case and covered with a brass mat and sheet of glass. The ambrotype image is a silver image in a collodion binder on glass.
Collodion is a form of cellulose nitrate dissolved in ether and alcohol.
The negative image produced is viewed as a positive image when the glass is backed by a dark material such as paper, paint or cloth. It is suggested that you not attempt to clean or remove them from their container without a conservator s help. The metal was painted dark brown or black, exposed, developed, fixed, and then varnished. The image, similar in tone to an ambrotype, was occasionally hand tinted and often encased in a paper holder or album. These prints consist of light sensitive silver salts in egg white on high quality papers.