PDA

View Full Version : Autochrome



barnacle
4-Oct-2016, 13:44
Autochrome.

As far as I know, no-one is working autochrome, which is not surprising as it's a bit bloody complicated...

Potato starch grains are dyed as a trichrome (e.g. red, green, blue) and randomly scattered on a sheet; the gaps between filled with carbon black. This makes a mosaic filter, which is bound to a negative which is exposed through it. The negative is developed and reversed, and the image viewed through the same filter, backlit.

This is going to be entirely experimental, and if it happens at all, slow - but potato starch is easily obtainable, so the next challenge is to die it. Anyone got any suggestions? I'm thinking food colours but I'm not at all sure what will happen :)

Of course, if anyone's already done this I'd be very happy to hear how!

Neil

jnanian
4-Oct-2016, 14:12
neil,

there was someone on apug about 10 years ago, htmlguru ( i think ? ) who
was working on re-inventing the autochrome. i lost track of how far he managed to get ...

on the topic of autochromes ...
i think you spelled the starch wrong :)


https://www.youtube.com/watch?v=Wdqbi66oNuI


have fun with your project!
john

Dustin McAmera
4-Oct-2016, 15:35
There's this guy:

Autochromes contemporains (http://www.autochromes.fr/) by Frédéric Mocellin. Found him while looking for things to link from our short article on Autochrome (http://camera-wiki.org/wiki/Autochrome) at Camera-wiki.

Drew Wiley
4-Oct-2016, 16:19
I'm aware of a couple of people experimenting with it in recent years, with so-so results.

Steven Tribe
5-Oct-2016, 00:49
I got as far as dyeing starch grains, mixing proportions as recommended and coating and rolling to flatten the grains, and finally, filling with fine carbon. The result was quite green in colour and probably too thick a layer. I must have a look through a microscope sometime this winter!

I used commercially available wood staining dyes.

LabRat
5-Oct-2016, 04:19
I started collecting vintage autochromes about 25-30 years ago (before they were "re-discovered"), and looked into what was needed to make my own... I had found some theory descriptions on how they were produced, written-up in old photo-technical textbooks... It didn't sound easy... (What could possibly go wrong!?!!!!!) :-(

I barely remember now, but the first major problem was that there has to be a almost perfect match of the amount (down to a almost exact #) of the three color batches of the RGB starch grains amounts, then these had to be mixed so there was a perfect random distribution of the grains on the plate for an even color balance... Then there was the issue of evenly coating a emulsion of (presumably extended orthochromatic) to a uniform thickness (so there would be a uniform speed to expose it at)... Ugh!!!

The Lumiere patents for the apparatus (gear) needed for making the RGB matrix can probably be found (and back then, it was probably non-electrical), and be built by the engineering partnership firm of Wallace & Grommet Ltd today on commission... There were probably different designs of swirlers and shakers needed, then there's a way to make the uniform thickness emulsion... (But there might be a way to strip an emulsion off an existing film...) And get the colors to balance...

Someone that was helping explain this to me was the former technical director of Technicolor... He wryly told me that there were easier difficult processes to try... ;-)

Steve K

Ralph Barker
5-Oct-2016, 09:52
I changed the thread title to something useful.

DrTang
5-Oct-2016, 10:20
Hmmm..why stick to true-ish color? I bet one could get cool results using two colors or three different ones ..like the duo-tone and tri-tone effects I used to amuse myself with in Coral-paint

barnacle
5-Oct-2016, 10:54
Thanks guys,

I did have one thought which was to create the filter using transparent plastic and a photoprinter... could look a little mechanical, though. Would do to start as a proof of concept though.

Steven - how did you use the dye?

Neil

barnacle
5-Oct-2016, 11:43
A possible link: www.isaet.org/images/extraimages/IJCEBS%200101102.pdf

el french
5-Oct-2016, 13:08
Perhaps a small random orbit sander attached to the build plate would distribute the starch grains evenly. A paint spray gun is capable of putting down a precise thickness of paint so it may work for the emulsion.

Dustin McAmera
5-Oct-2016, 14:46
What about a half-cheat: you could step past the starch part of the project (at least for now). It ought to be possible to prepare an image consisting of random coloured dots in three colours, and print that onto a flexible plastic backing (I'm thinking of an OHP slide). Maybe you have to varnish that to protect the colour-screen image; then coat it with the gelatin emulsion (again, at least at first, I'd buy emulsion in a bottle).

This way, you would have sheet film, not plates, and an emulsion that ought to work. You can concentrate on the practicalities of exposure and reversal development, and developing a colour set that gives a good result. You can always add back the extra difficulties of glass plates and starch later.

Steven Tribe
5-Oct-2016, 15:07
There were patented processes which used micro dot random colours (Dufay?) on plastic after lumiere.

My system of coating was clear spray lacquer with the mixed grains applied instanteously and excess removed straightaway (gravity and brushing)

Drew Wiley
5-Oct-2016, 16:08
There were dozens of different color processes. Autochrome was one of the first, but not the very first by any means. Otherwise, wood dyes are one of the worst
choices possible because they are mostly fugitive analine. If you want to see a gritty slightly off-color but gorgeous print process, look at color Fresson. It's a well
kept trade secret, true pigment screen process in the direct-carbon category (versus carbon transfer). As primitive as Autochrome was, it was still an industrial
process that required not only its on R&D phase, but skilled workmen and standardized industrial ingredients and equipment. Another once-popular process that is
difficult to reproduce on a do-it-yourself basis is color Carbro. Dye transfer is more realistic.