Ambrotypes were a direct positive process effect achieved on glass coated with light-sensitive collodion, backed with black paint, paper or even black velvet.. It is also known as a collodion positive. They are often confused with Daguerreotypes because they were often housed in dag cases and confused with Tintypes because the images look very similar.. The process was invented by Frederick Scott Archer and Peter Fry in 1851, but was patented in the US (Boston, MA) by James Ambrose Cutting in 1854.
.James Cutting was born in Worcester, Massachusetts, in 1814. His family moved to Vermont and took up farming and there Cutting devised and patented a new kind of bee hive, bringing him profit and renown. He was not a very adept investor, however and he soon went broke and came to Boston where he tried his hand at making daguerreotypes. He is credited with the discovery of a process for making pictures on glass called ambrotypes (after his middle name). His method of photos involved a glass sheet for photos that was covered with collodion for photos and that was underexposed or bleached. Ambrotypes are sharply detailed, one-of-a-kind photographs on glass, packaged in protective cases similar to those used for daguerreotypes*. An ambrotype is basically a collodion* on glass negative that is intentionally underexposed so that the negative appears as a positive image when viewed against a dark background. Ambrotypes soon replaced the more expensive daguerreotypes as the favored process for portrait photography. The process has the additional benefits of being non-reflective, making ambrotypes easier to view than daguerreotypes.Ambrotypes were mainly used for portraiture thus outdoor scenes are more rare.
No lateral reversal (no mirror image)
The popularity of ambrotypes was short-lived, however, and the process was soon displaced by the growing popularity of the negative-positive process of collodion on glass negatives and albumen prints.
*A Daguerreotype is a photograph that is produces on silver or on a silver covered copper plate.
*A Collodion is a solution of pyroxylin used as a coating for photographic films.