Autochromes...

[jd callow]

Very possible Ole. I have never seen one first hand and most of the sites I have viewed I have had to translated.

My item 5 and the digital step may be furthering a mis conception started by another or (less likely) a mis reading of a translation.

I have also read that the process started in 1907 and 1904 and ran until 1933 or 1937.

One translation was rather neat in that it stated the brothers 'light' invented the process and film.

 

[htmlguru4242]

Let's shift the focus here back to actually making the slides with current technology...

1. Coat dyed starch grains + coal dust in a varnish and / or honey mixture and harden. This was on a glass plate.

2. Coat a panchromatic emulsion over this - losing a huge amount of speed.

3. Expose through the glass plate.

4. Reversal process in a normal B&W process.

5. View.

Is definetely the correct process. There were a few steps in between those (such as one that flattened the startch grains), but that would be unecessary for testing purposes. Also, I believe that the original plates were slighty concave, allowing for easier coating of both emulsion and filter screen.

I'll work in printing onto film and making a screen. However, the question still exists as to what you can use for water insoluable dyes / pigments. I'm still in need of ideas...

 

[jd callow]

Why not shoot through the film as the original was shot through the plate? This way, I would imagine, you would have any number of ways to seal the colour and filter layer.

 

[htmlguru4242]

hmmm .... that is a good idea- a coating could easily be made on hte base of the film. hte only problem would be removing hte anti-halation backing that is present on almost all modern films. I do not know of any (with the exception of Kodak HIE, which isn't suited for this) that would work.

Does anyone know of films with no anti-halo coating and a relatively clear base, or of any way of removing the anti - halo base from films that have it before exposure?

 

[Photo Engineer]

I would suggest any good sulfonated azo dye for starters. There are some still used for Dye Transfers and their names are posted on the SIG web site for Dye Transfer enthusiasts. Some good food dyes might work if they are suitably immobilized by a mordant.

You may need a quaternary ammonium salt to function as a mordant on the starch, to hold the dyes in place in case they tend to wander. It depends on how mobile they are during coating and processing. That will have to be experimented with.

If you have a removable screen, you have the very difficult task of re-registration after processing, mentioned above, and which will cause color fringing and halos at best, and no suitable color image at worst.

Most films have antihalation that is removed only by processing or wetting which will ruin the film for this application.

That does not mean that this cannot be done, merely that a lot of searching for the correct materials will have to be done before a start can be made.

Remember that the number of grains and their size are determined by the size of the original transparency.

PE

 

[htmlguru4242]

I didn't realize that the removal of hte anti-halation backing would be that much of a problem. Can the film be exposed through the base, or does the anti-halo layer completely block all light?

 

[Photo Engineer]

I didn't realize that the removal of hte anti-halation backing would be that much of a problem. Can the film be exposed through the base, or does the anti-halo layer completely block all light?

Film can be exposed through the base with a loss in speed of at least a stop, if not more. Depends on the film. Each film and each manufacturer uses different levels of AH. Some are on the back and some are in an undercoat. Some are just dyes in the film itself.

PE

 

[Donald Qualls]

Most films lose 2 to 4 stops when exposed through the antihalation base; many antihalation layers are also strongly colored (Foma, Lucky, and J&C Pro 100, for instance, have a dark blue base color before processing). And of course exposing through the base adds an additional complication when using 120, because you'd have to untape the film from the backing, print it, and tape it back the other way around. And then you'd have to worry about putting an impermeable layer over the antihalation (which is commonly coated on the base side, in the anti-curl layer, for films that have this, though some films have it on the emulsion side in a layer beneath the sensitized layer).

However, in addition to Kodak KIE, Maco IR820c Aura (another infrared film) has no antihalation, and can be had in sheet format as well as roll films. It's much slower than HIE in visible light, and a bit slower in IR. There may also be copy films that have no antihalation and are panchromatic, though copy films are generally quite slow (to allow comfortable exposure length under an enlarger or in a contact printer). I had envisioned this in large format; the bigger the negative, the less fine the filter matrix need be to give acceptable image quality, and exposing through the base is at least possible. And obviously the faster the film, the more speed loss can be tolerated due to the filter matrix.

I see potential problems with mordanting the dyes; if done with a bath after printing the filter matrix, but before exposure, the mordant bath is likely to (at a minimum) remove sensitizing dyes from the film, further reducing speed. In addition, I'd be concerned that a mordant might tend to harden the gelatin, which would affect process times. If the mordant is part of the ink, the same problem occurs with potential hardening, though at least one needn't worry about loss of sensitizers.

Most ink jets use either piezoelectric actuators (HP? Lexmark?) or strong, rapid local heating with associated steam bubbles (Canon, Epson, probably others) to fire the ink. The latter is strongly dependent on the ink having a boiling point very close to that of the original formula, but a piezoelectric head could spray (for instance) organic solvents (anything from acetone to xylene, in principle) carrying water-inert dyes that could penetrate the gelatin without washing out once dry (dyes from Magic Markers or similar permanent fiber markers would be a good first hack). Surface tension might be an issue (both in droplet formation and spreading after impact), but can be tailored to some extent in formulating the dye ink.

As I recall, the potato starch in the original autochromes was protected from developing chemicals by the bitumen matrix, so those dyes didn't need to be water inert.

 

[Photo Engineer]

Donald, I really meant that the dyes be imbibed into the starch and then mordanted before coating, but if you use a solvent based dye, then they probably would remain in the starch and not wash out. Of course, coating with any resin would protect the dyes in the starch grains. Water soluable azo dyes are easier to come by in most cases.

The speed losses cited in the literature using an emulsion over a screen or mask of this sort was stated as 40X. What that means in today's terminology is vague, but if you consider it to be in terms of LogE, then the speed loss of the Autochrome starch/coal mixture would be on the order of 4 stops. A 160 film would give you about ISO 10 by that reckoning.

Exposure through the AH layer, even if colored, is impractical, but might be overcome by balancing the dye screen against the color of the AH layer. This is not very practical and would lose more speed.

Along the lines of this discussion I am reminded that "an apendectomy can be done via the mouth, but the results are not optimum for the patient". This is an elegant art form, but starting from scratch will need much research and much trial and error in order to achieve usable results. It will involve long hard hours of work and lots of failure in the inital stages. The final result, if carried through, will probably be a magnificent revival of a vanished art and an inspiration to us all to achieve more.

PE

 

[htmlguru4242]

I just want to clear a few things up here... Photo Engineer, you're discussing something a little different than what Donald and I have been talking about. You've mentioned applying starch grains to the film as in the original process, which would be our end intent. However, what Donald has [might I add, brilliantly] suggested, is that you use a standard inkjet printer to physically print the screen onto the emulsion side of the film from an image created on a PC. This would give the advantage of being relatively simple, and would use available and tested equipment. The only problem, as Donald said, is mordanting the dyes once they are in the gelatine.


As to maing other dyes for piezo. heads, I was certainly thinking along those lines. Pigments dissolved in solvents (i was thinking alcohols or xylene, as acetone does some nasty things to film base, plastic and gelatine), could work well. The colorant from fiber markers would probably work, and I was also thinking about artists inks or even fabric dyes - not so sure about htose, though. I'll crack open an old ink cartridge to see what hte approximate consistancy and surface tension are.

I hope we're all serious about reviving this process, becuase PE is certaintly right that its revival will be magnificent. (Would it not be cool to have it finished and ready to go by 2007 - 100 years after the plates were first released?)

 

[Photo Engineer]

I fully understand what Donald is suggesting. The idea has not passed me by. See my comment (GMTA) above.

Making the screen by that method would be elegant, but more akin to Dufaycolor rather than Autochrome, not that it makes much difference in the end really. Both achieved the same thing by different routes.

Let us define our terms then.

A regular screen pattern of dots, laid down in a controlled method and used is Dufay, an irregular screen laid down in a random method is Autochrome, and the use of lenticules is a third method not under consideration.

Exposure of pre-manufactured films using any of these methods would involve exposure through the base with loss of speed and color shifts possible and exposure through the emulsion side with removable screens would cause re-registration problems with dire concequences. Exposure through the emulsion side through a printed screen presupposes that the printing process can be done in the dark and that the inks allow for processing to take place with no effect on the emulsion.

That is my summary.

All are diffucult, elegant and if even one of them works, it will be as I said above, a magnificent achievement and an inspiration to us all.

Probably being one of the few here on this forum that has made a color material from start to finish (I mean that exactly as read) and having done it by hand as well as by machine, I know exactly in painful detail what you all face. I wish you the best, and I will help in any way possible to make it work for you.

I think that your best hope is to duplicate either the Dufay or Autochrome materials as is for starters, as that is a base point. That is my suggestion.

PE

 

[glbeas]

With that in mind, I've encontered whats called cleanup sheets on Ebay, which are film base with gelatin coating but no emulsion. Used to pick up dirt from the processor rollers prior to putting the good stuff through. Maybe print the matrix on this, then coated with a pan liquid emusion and go from there. I'm wondering if the Epson Ultrachrome inkset is transparent enough to work. They are water resistant, you can dip the print in water and not hurt it.

I've mentioned the cleanup sheets to Jorge and he was interested enough to say he was going to try to get some for carbon printing. He might be able to tell you some more about this material if he was succesful in getting some.

 

[jd callow]

I was trying to think of where I had seen 'blank' film. Ebay -- where else.

 

[glbeas]

This stuff is a Kodak Product, probably other film manufactureres make a similar product. Won't hurt to check.

 

[htmlguru4242]

Sorry about misreading your post, PE, i did not see when you were also talking about the printed screen idea ... oops

Anyway, since you've designed color materials,I'm assuming that you've either designed a panchromatic emulsion, or used as liquid one, either case whuch would be useful for this. What did you use for your emulsions for these materials?

 

[Photo Engineer]

I'm sorry, but all I have is an orthochromatic ISO 25 speed AgBrI emulsion of my own. I am working on a better version and may have a panchromatic version soon. I have taken pictures in-camera giving me a paper negative, and it looks fair all things considered. My original goal was not camera speed and not pan sensitivity, but events have pushed me in that direction.

I know of no comparable commercial liquid emulsions. There are a host of them in enlarger speed ranges with blue sensitivity, but that is about it. The VC versions of these have some green (ortho) sensitivity.

I would need to make an ISO 100 - 400 pan sensitive emulsion to fit your needs. It is doable, but not quite yet.

As for the actual design of the multilayer color materials I did coat, all of them were done at Eastman Kodak on product design projects. Small samples were hand coated and larger samples were machine coated. All chemicals and formulas involved were proprietary and most were custom made for the projects.

PE

 

[jd callow]

I am way out of my depth when it comes to adding much of substance to this discussion. Having said that I have one question.

Would it not be somewhat easier, if only initially, to skip the reversal step and produce a colour negative?

The red mask could be added in the enlarging step as well as addressing some of the fidelity issues. I can only imagine that as hard as it will be to overcome the coating issues the colour fidelity issues will be infinitely harder.

From here I'll be a voyeur. If you should require the use of a colour darkroom, mine is available.

 

[Photo Engineer]

Autochrome and Dufaycolor are additive processes (R + G + B = White) not subtractive (C + M + Y = Black). This does not lend itself well to making color negatives which rely on subtractive methodology for printing. It could be done, but adds a lot of problems.

In fact, the dyes on the starch grains are RGB not CMY as in current color materials, and spectral sensitivity has to match that needed for an additive process (no big deal, but just a side note).

This has not previously been mentioned in this discussion, but should be brought up and discussed based on your comment. The azo dyes I mention above are CMY and would not be suitable as dyes. A shifted set of RGB azo dyes would have to be selected.

PE

 

[Ole]

Maybe some of the contemporary sensitising dyes could be added to liquid emulsion to make it panchromatic? I'm about 1000 km away from home, but I'm sure I have some potentially useful literature (Eder's "Das Arbeiten mit farbenempfindlichen Platten", for instance).

 

[htmlguru4242]

I don't think that finding dyes will be an especially large problem. There are plenty of RGB - colored dyes that are not water soluable out there.

Also, on another side note, if we want to exactly duplicate the original process, Orange, Violet, Green Dyes were used

I located this close-up of the autochrome mask...

 

[Photo Engineer]

I don't think that finding dyes will be an especially large problem. There are plenty of RGB - colored dyes that are not water soluable out there.

Also, on another side note, if we want to exactly duplicate the original process, Orange, Violet, Green Dyes were used

I located this close-up of the autochrome mask...

Those names might just be what they used for R,B,G then as a compromise in dye names/hues that were available. Many of today's azo dyes were not available back then. The concept of subtractive color systems was in its infancy then and the use of the CMY names were not common.

In the photo appended, the carbon black/coal dust filler is not as apparent as I have seen in other photomicrographs.

Ole has a point about redying an existing emulsion, but the problem is that the cyanine and merocyanine dyes useful for sensitization just cannot be bought over the counter. They are very hard to get and expensive. Consider that the cheapest sensitzing dye I can find on the market costs over 5x the price of gold, gram / gram. That is not inexpensive. I had to buy 4 of them to find the one that worked. As a result, my sensitization experiments ended up costing about 20x the price of gold and were the single biggest expense in my photographic budget. To get a panchromatic dye, or a red dye would be a similar expense, not to mention the IR equipment for handling the raw materials. In any event this work has to be done.

It is like looking for a solid gold needle in a haystack.

Another problem is that the liquid emulsions on the market today are no faster than mine, and perhaps slower. IDK, not having tested them against mine. They cannot be very fast if they are intended for use as an enlarging paper emulsion.

PE

 

[htmlguru4242]

Well then, due to the expense of panchromatic dyes, it would seem as if our best bet would be to atttempt modification of an existing panchromatic film, as it will result in a far lower expense. If the dyes are 4x more expensive than gold, than event buying the large quantities of sheet film required for experimentation will be significantly cheaper.

Just a random idea ... would it be possible to melt the emulsion off of existing film with the aim of recoating it onto another plate? Because if that was possible, our task would be quite a bit easier. The only requirement for that would be IR / night vision goggles so you can see what you're doing, and they can be hacked together for about $400 - 500 US...

 

[Ole]

Another brainstorm (or light breeze): Coat mask on glass, then put film onto glass, remove film support. Not quite as easy as a polaroid emulsion lift, but somewhat similar. With all the different ways there were of accidentally making the emulsion slip off glass plates (one of my books devotes 30+ pages to this), it must be possible to make the emulsion just slip off a sheet film?

You would then have to expose through the glass, but if they could do it then it should still be possible today

 

[Photo Engineer]

Emulsion lifting before processing will destroy the emulsion. The heat and moisture involved would destroy things.

The enzyme 'takamine' will dissolve hardened gelatin at room temperature turning it back into soup, but recoating and rehardening might be hard unless you could deactivate the enzyme before recoating. Also, takamine is dangerous to the untrained, as it can dissolve human skin and etc. Not very healty to inhale the dust either as it is a severe lung irritant. That is the only way I have ever heard of doing what you describe though.

I like Ole's idea, but find no easy way of reregistering the mask, unless the mask is very regular such as the Dufay mask. In fact, thinking it over again, the Dufay method would be better than the Autochrome method due to regularity and lower reregistration problems.

Is there any reason you prefer Autochrome over Dufay?

PE

 

[htmlguru4242]

I think that ole's idea is a good one. Although it is not simple in excecution, it will be quite a bit easier than some of hte other methods that have been suggested. As to preference between Dufay and Autochrome, it's really not of significance. The overall effect between the two is subtly different, but I think that with our testing, either process can function as an intermediate or evolutionary step towards the other.

If we're all serious about re-creating this, I think that whatever process is easier (which probably is Dufay) should be tried first.

In the meantime, I'm trying to find a way to coat over the front of gelatine on film that will hold starch grains, but will not affect the absorption of developer into the emulsion significantly. I'll see how that goes.

I also want to state how impressive the knowledge, creativity and promptness in response the members of this forum have is.