Thank you Jon for putting out such a comprehensive how-to on this truly archaic process. I bet every sentence over there signifies weeks if not months of trial and error on your part. So kudos!
OK, but now I am going to ask for more. I feel it will be even more awesome if there was a background write-up as a way of introduction for the novice as to what an Autochrome is, principles - physics and optics - behind it. A schematic of the build will be tremendously helpful to understand and appreciate the various steps involved in producing the plates. This information is hard to come by elsewhere - so I have found.
A question:
Can one use one of those commercial emulsions instead of diy'ing it? In other words, is there anything special in your recipe that is essential which is not found in the commercial variety?
And a wild idea: Along the same lines as using the LCD display panel, I wonder if an inkjet printed plate - with a randomized pattern of RGB inks (dye-based better for transmissivity?) might be a substitute for potato starch.
Thanks again for sharing this great resource.
:Niranjan
That's actually a super good idea, and if I had thought of it first I would've delayed sharing this a few days to include something. If I have time this week, I'll try and slap together a "Part 0 - What Is An Autochrome, exactly?"
As far as commercial emulsions -- I *think* you could, but I'm not 100% sure. One major point I was able to discover, is that if any surfactants are in the emulsion at all (e.g. even a few drops of Photo-Flo, as is standard with DIY emulsions) cause massive issues with the emulsion lifting during development. I'm not sure if commercial emulsions have this or not, but this would be the only major "show stopper". All you would need to do to is add your spectral sensitizing dyes and find the right dilution, since my emulsion is super thin. And maybe toss some chrome alum in there too.
I kiiiiind of did a little work with film applied to some sort of dye printed pattern. See
Pseudochrome.
Brutal website Jon. Real tour de force of different techniques.
Could i ask about your pseudochromes? I dont want to litter this thread with it tho.
Sure! They were my very first attempt at something autochrome-like, not long after I had learned about how the process works. This was years ago and I was in between jobs, with a dinky darkroom and dinky equipment, so calling it "half-assed" would still be saying too much. Quarter-assed, tops. Someone else had helped me design a few large grids of RGB and CMY noise, which were printed out on some fancy printer on transparencies at a nearby art school. Those were cut up, and then glued with rubber cement to little strips of film that I taped in to a 4x5 film holder and exposed. Tray development, probably with D-76, stop, and fixing as is typical. Color response wasn't great, but as I recall the scans I shared on my site are even worse (I was probably holding a flashlight behind the strip of film and trying to photograph it with a camera phone from 2011). I recall being very excited when that traffic cone turned out a deep "blue", and it's totally possible (and probable) that better results could be obtained with a more careful approach. Unfortunately the noise pattern files have been lost to the ages, as well as all the actual "pseudochromes" I made, so I can't share them any further. Feel free to ask pointed questions about it if you have any, but this was about 7 years ago and details are a bit hazy. Larger pieces of film (4x5 and up) might suffer from parallax desaturation, meaning if the emulsion is spaced too far away from the screen, your viewing angle becomes limited, and the image loses its color if you look at it at any angle that isn't straight on.