Old Photography Process: Tintype
Tintype is a type of photography process that reached it’s highest success and widest use during the 1860s and 1870s, although the medium was still in use in early 20th century. It is hard to accurately say where it originated from, since it was simultaneously patented in both United States and United Kingdom by Hamilton Smith and William Khloen. Process itself is based on creating a direct positive on a thin metal sheet or plate coated with enamel, acting as the support for the photographic emulsion. Process is also known as the melainotype or ferrotype process, and it is still present 21st century, revived as a photographic novelty.
There are two versions of tintype process. Older and less convenient one was the wet process. Wet process is based on producing image by exposing the metal plate coated with collodion emulsion in the camera while still wet. Collodion emulsion that contains suspended silver halide crystals that is used in the wet process was a bit difficult to use due to the fact that the plate had to be prepared shortly before the use. Chemical reduction of microscopic particles of silver, being exposed to the light, depending on the intensity and duration of the exposure then resulted in visible picture.
Dry process, although similar, brought improvement – more regarding the convenience of the process itself, then regarding the image quality. Dry process is based on the improvement of the collodion emulsion into the gelatin type emulsion, easier and more convenient to use due to the fact that it could be applied to the plate long before the use.
Both processes had the same result; very underexposed image created in the emulsion. Reflected light made its densest areas appear gray corresponding to the lightest part of the object being photographed.
The deepest of the tone scale of the picture were the areas least covered with silver particles. Thin and light layer of silver appeared transparent and barely visible, therefore seen as the black on the final image, due to the dark lacquer covered background.
Fixer used to obtain the lightest- toned image possible was potassium cyanide, which is today recognized as highly toxic and deadly.
The picture created from the original plate was the mirror image, usually reversed left to right. There was also a possibility of fitting the camera into the mirror image position towards the reality, so that the end result would be spared of the previously described flipping.
Regular tintype equipment was based on the twelve-lensed camera capable of producing dozen of “gem” sized pictures in one exposure. Portrait sizes ranged from the 19mmx25mm gem size up to the 280mmx360mm.
Tintypes owe their success and popularity to several facts. They were relatively easy to make on the spot, which shortened the delivery time drastically. In several minutes, photographer was able to do the preparations, to expose, develop and varnish a tintype.
Other important improvement was that, unlike daguerreotypes, tintypes weren’t expensive. Being more affordable, easier and quicker to make, tintype process was widely recognized and excepted.