Wet Plate Tintype
Wetplate, or wet collodion process dates from 1851 through the work of Frederick Archer. A plate is coated with cellulose nitrate, an iodide, and silver nitrate. The plate is then exposed and processed while still wet. The tintype is a version of wetplate which utilizes a sheet of black painted metal.
Dry Plate Tintype
Dryplate tintypes use modern chemistry made by Rockland Colloid to make dry-plate tintypes. The advantages of dry plate to the historic wet plate process include simpler procedure (with less chemistry to work with), less toxic chemicals, easier handling of plates, ability to use the plates out in the field and deferring development for a later time. All in all, it’s an easier and more accessible way to do tintypes.
The ambrotype is a positive photograph on glass and is a variation of the wet plate collodion process. Like a print on paper, it is viewed by reflected light. Each print is a unique original. The ambrotype was introduced in the 1850s. During the 1860s it was superseded by the tintype, a similar photograph on thin black-lacquered iron, hard to distinguish from an ambrotype if under glass.
The salt print was the dominant paper-based photographic process for producing positive prints during the period from 1839 through approximately 1860. A photosensitive surface is made by wetting a sheet of paper in a salt solution and coating one side with silver nitrate. A negative is then laid over top of the paper and exposed to light. The result is a positive photographic print on the paper.
Reversal prints are produced by exposing photographic printing paper directly within a large format camera. The paper is developed normally, producing a negative image. The paper is then bleached to lighten the exposed areas and render them insensitive to further exposure. A second over-all exposure to light causes the formerly light areas to darken during a second development. The result is a positive print made without the use of an intermediate negative. The process is similar to dry plate as the paper is quite slow compared to film. The resulting image is mirror-imaged as it is made by direct exposure within the camera.