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I am trying to figure out what type of photography gives the silver (reflective) twinge to photographs like old historic photos. I have started looking in to wet plate photography ...
You're not thinking clearly here. You're saying "photographs" when you mean "photographic prints" and then getting mixed up with various processes for producing the "photographic negative" rather than the print. In processes where there is a negative and a print (e.g. virtually all "wet plate" process variants along with modern gelatin based processes) the process used for the negative has nothing to do with the color, surface sheen, texture, or metallic reflectivity of the print.
There are two groups of antique prints that exhibit a metallic sheen. The first are those where the sheen was intentional or a basic characteristic of the process. The most pronounced of these is the Dageurreotype, which is a weak image on a polished silver plate. The polished plate must be held properly so that its reflections create a positive image. When tilted at different angles to the light it will show as a negative. Daguerreotypes are extremely fragile and must be kept sealed in a case to protect them.
Two other processes, the Ambrotype and the Tintype, are basically the same collodion binder (like the later "wet plate") process that yields a positive image when the otherwise "clear" portion of the image is made black. In the Ambrotype the image is on a glass plate and a piece of black velvet or paper is mounted behind the glass. These are generally bound in cases like the Daguerreotypes to keep the pieces assembled properly and to give an appearance similar to the presentation of a Daguerreotype, which was the popular process in the day. The Tintype replaces the glass plate with a sheet of tin plated steel that has been Japanned (early 19th century term for a smooth polished black lacquer finish). The rugged image combined with the very rugged support contribute to the larger percentage of these images that have survived. They were also inexpensive to make and survived as the quick photo process well after otherwise better processes were introduced.
The other type of metallic sheen is the result of aging and it is, in actuality, a fault in a less than well processed or stored image. The image, either print or negative, would not have had that sheen originally. The common type is silver sulfide staining, also called "silvering" or "tarnish". This can happen to either prints or negatives. It shows most in the darker areas of a print and when weak and uniform it will lend a metallic sheen to the shadow areas that seems intentional.
There have been a number of toning methods that produce beautiful deep blacks. These can, when combined with a very glossy surface, can give somewhat of a metallic impression, but don't really produce a metallic surface reflection. There have also been some special toning methods designed to leave a shiny metal look, but these are not what you would see in real antique prints.