suejulene said:
My mother recently gave me about 50 tin type photos from our family. What does anyone know about tin types and care of them? Would they originally have been so sepia/brown colored? What is the difference in process between deguerrotype and tin type?
Thank you.
SueJulene
Tintypes naturally have what is referred to as a "coffee and cream" appearance.
Tintypes (also called ferrotypes or melainotypes) are derived from a wet collodion process as are ambrotypes and the original wetplate negatives on glass used for albumen printing. These processes were popular from about 1851 until the 1880s when dryplates really came on the scene. The difference in these wetplate processes is the substrate the collodion is poured onto, a thin jappaned iron plate in the case of tintypes or a sheet of glass for ambrotype positives and wetplate negatives.
The emulsion, which is poured onto the plate by hand, consists of iodized collodion (gun cotton dissolved in ether and grain alcohol with either/both cadmium-, potassium-, and/or ammonium iodide added to the viscous mix). The plate is then sensitized by submersion for several minutes is a bath of silver nitrate under safelight/nonactinic conditions. The wetplate is then loaded in the special holder, transferred to and quickly exposed in the readied camera, then taken back in the darkroom for immediate processing in a ferrous sulphate or pyro developer. The plate is then rinsed and fixed, washed and then varnished. All this (except the varnish) has to be completed before all the ether and alcohol evaporates which leaves the plate dry and impervious to the chemical effects.
A daguerreotype on the other hand is essentially a photograph produced on a silver-coated polished plate, i.e., a mirror surface. The chemistry involved is different involving I believe, various bromine and iodine salts as well as development in mercury fumes. Perhaps a daguerreotypists can chime in here with a better explanation of that process.
Daguerreotypes, ambrotypes and tintypes are all unique positives which have the image reversed as in a mirror. You can tell them apart since the daguerreotype generally will appear as a ghostly negative until something dark is reflected in the mirror surface which causes the white powdery negative image to suddenly appear reversed. This is the reason you'll find dark velvet incorporated on the adjacent leaf of a cased daguerreotype. OTOH, ambrotypes and tintypes are really severely underexposed negatives which owe their apparent reversal to the black background upon which they reside . Without the underlying black surface, an ambrotype image appears like a thin glass negative. Tintypes, being on iron plates, are magnetic as well. Modern wetplate photographers are beginning to use thin, black-anodized aluminum sheets as a substitute substrate for the traditional jappaned iron sheets. (I propose calling them "alumelainotypes" which is a tongue twister but descriptive.) These look like tintypes on the obverse but eliminate the messy japanning step of traditional tintypes.
Joe
