Ever since I first became interested in photography, I've always wanted to do everything from scratch, from start to finish. Now with black and white processes this isn't too terribly difficult -- I've done both wet plate collodion and dry gelatin bromide, both of which satisfy this urge. But I've never been able to capture a color image all by myself.
There are two feasible options for me to remedy this: The Lippmann process and the Autochrome process. I plan on covering the Autochrome process in depth in a following post.
Lippmann plates utilize fairly standard gelatin bromide chemistry -- just really slow. The emulsion requires two things: extremely fine grains, and it needs to be fairly transparent. Why does it need to be transparent? Because instead of having the emulsion side facing the subject in-camera, the plate will actually be exposed with the emulsion side facing away.
The light entering the camera needs to pass through the emulsion and then immediately reflect off of a mirror in OPTICAL CONTACT with the emulsion. Originally Gabriel Lippmann used mercury in a special plateholder, although there are alternative options for this mirror that I will cover below.
The reflected light creates an interference pattern, which gets recorded into the gelatin bromide emulsion. Upon development, a color image can be reproduced when viewing the plate with incident light. Although there have been a few other indivuduals to make modern Lippmann plates, this is somewhat of a lost process that I have a huge amount of interest in.
THE TENTATIVE PLAN:
This formula has been lifted (and paraphrased) from page 193 of An Experimental Study of the Lippmann Photograph
A. 1g Gelatin
B. 2g Gelatin
250mg Potassium Bromide
C. 300mg Silver Nitrate
UNDER NORMAL LIGHTING:
Heat solutions A and B until the gelatin melts. Cool to 110F. Add C into A.
UNDER RED LIGHT
Slowly add A into B with constant stirring.
UNDER NO LIGHT
This is where things start to deviate. You need to add sensitizing dyes to make the emulsion sensitive to things other than blue. My plan is to use 0.5cc of:
1:5000 Methyl Violet
Methyl Violet should add orange (possibly some red) sensitivity to the emulsion and thus a red light can't be used. I've been using an Eyeclops night vision goggles I got cheap off of Amazon.
Pour the plates and wash in cold water for 15 minutes (this is necessary to remove various water soluble salts created during the reaction). After washing, set to dry somewhere in complete darkness.
If I want to shoot in the field, in public, there is no way I can use mercury. There are a few options here:
1. No mirror. The Air/gelatin boundary will provide the interference needed. The plate holder will need to be backed with velvet to avoid scattered light interfereing with the image. This comes at the loss of the "brilliant colors" that mercury provides.
2. Gallium. The metal can be melted and smushed in contact with the emulsion and allowed to solidify. Potential issues include it being stuck to the emulsion or leaving marks on the emulsion (gallium is SUPER messy).
3. Silver mirror. There are references in the aforementioned study of silvering a piece of glass, lifing the silver with a cellulose varnish, and placing the silver in contact with the still wet plate. The drying times are very long but this apparently works just as well as mercury.
4. Mirror film. Using the same method as in #3, but applying a commercial mirror film instead. Mirror film is almost exclusively covered with a layer of aluminum oxide, which apprently doesn't work. But I ordered a bunch accidentally so I might as well try.
A: 1g pyrogallol
B: 15g potassium bromide
30mL saturated ammonia
3mL A + 6mL B + 100mL water
No stop bath or fixing is required (as fixing apprently alters the microscopic structure of the Lippmann emulsion and messes up the image)
After that... BAM! We should have our color image.
I will continue to update with my successes and failures!