Collodion Emulsion - emphasis on EMULSION
I was recently recommended to read Collodion Emulsion and its Applications to Various Photographic and Photo-Mechanical Purposes with Special Reference to Trichromatic Process Work, by Henry Oscar Klein. (available here). Ask for that at your library 5 times fast!
In short, this process is distinctly different from wet collodion and those collodion dry plates that used various humectants. This wikipedia blip will give you the best description of it -> here.
The above book is fascinating. Basically, collodion emulsions can be sensitized to all regions of light and thus can be used for color photography. It uses aniline dyes to do this, much in the way that gelatin emulsions use dye sensitizers, but it appears that generally they're a different class of dyes (or are they?).
I don't have much to say on it, other than to just mention it, bring it to someone's attention if they've never heard of it, and to solicit any information about it. Frankly, I wondered where had this been hiding my whole life! It seems like a process that's really under the radar and particularly so considering the color bit.
Furthermore, it's claimed that the speed of these collodion emulsions, appropriately sensitized, can beat or match gelatin plates of the same era. This was how the majority of color separation work was done at the turn of the century I guess. Just imagine; the resolving power of collodion with full color sensitivity.
To Dr. Albert, however, is due the credit of having first discovered the surprising sensitising power of a very concentrated solution of eosin silver in ammonia. Without his example others Would not so quickly have come upon the interesting fact that it is possible to prepare colour-sensitive collodion emulsion attaining the sensitiveness of gelatine emulsion. Dr. Albert has thereby opened a new road. (from here)
The Many Flavors of Collodion
Yes, beyond wet collodion there is moist preserved collodion, dry preserved collodion, unwashed collodion emulsion and washed collodion emulsion.
The collodion emulsions are really interesting because they seem like they shouldn't work, given that they are in a binder that doesn't absorb water so easily when dry. Collodion chloride emulsions for printing out paper are the easiest printng process invented. Unlike gelatin emulsions, a beginner can make the emulsion and coat a perfect sheet of paper that looks like factory made on the very first try. And...the final product is more archival than any silver gelatin product. The way we identify collodion pop prints in conservation is that they are the ones that don't fade. ;-)
Washed emulsions like those described in Klein's book are also amazing...but require more money to make. The mixed emulsion is poured though water and the "noodles" collected, dried and then mixed with more alcohol and ether. Those are the ones that were dye sensitized. The earliest dye sensitized plates used chlorphyl as the dye and were simply silver bromide wet plates...which were then washed individually. Yes, you can make dry plate tintypes with a washed silver bromide collodion emulsion.... but wet plate is faster and cheaper.
We have a collodion chloride emulsion workshop in November for anyone who is interested.
Or contact me with questions...Mark firstname.lastname@example.org