Autochromes...

[ThePhotoChemist]

WOAH I'M BACK.

I was just wondering. I read that there are about 4 million starch grains per square cm in historical autochrome. That comes out to about 200 per linear mm depending on the packing.

Do/did you have to go to any particular trouble to make a fine grained emulsion? If the emulsion we're too course many silver halide grains would span more than one filter grains and the result would be much reduced color purity.

Nope. Even if I started sorting the starch and only using the smallest, the silver grains that I'm making are still several orders of magnitude smaller. I can't really offer much of an estimate on the silver grain size... I can barely even see them with the microscope! Fortunate or not, making a silver emulsion with large enough grains to rival the starch seems to be well outside of my current capabilities!

Here's a thought I had the other day:

Currently for first development we use a developer that produces a significant amount of fog to build density within the emulsion (which ultimately gets bleached out).
Instead of doing it during development, could one purposely fog a portion of the emulsion prior to coating - for example, separating 25% of the solution and allowing it to magnetically stir under light for 15 minutes before recombining it with the rest of the emulsion.

This would seemingly come with advantages and disadvantages compared with the current way of doing things.

Pros: Would allow for the use of a more standard developer, like D-76. In turn, this step would be less touchy in terms of getting the timing just right.

Cons: This would affect the whole batch, instead of on a per-plate basis.

Not sure if I'm going to go through with it, but I'm tempted to try it out with that beaker of emulsion that's been sitting around in my fridge for two months.

 

[Photo Engineer]

Fogging grains in reversal color is known to be used. It does just what you wish it to do here. It is done in making the emulsion though in the cases that I know of.

PE

 

[slackercrurster]

Isn't it crazy how the old timers made autochromes, yet we can't reproduce easily in 2018? They were genius at it. Especially in developing the process.

 

[NedL]

WOAH I'M BACK.
Cons: This would affect the whole batch, instead of on a per-plate basis.

But, at least for testing purposes you could try it on a per-plate basis. Make up a small batch of "fogged" emulsion, add it just before coating, only to the gelatin for one plate.
Perhaps mixing the "good" and "fogged" gelatin just prior to coating would not emulsify well enough, just a thought.

Glad you're back I enjoy reading about this!

 

[Nodda Duma]

Isn't it crazy how the old timers made autochromes, yet we can't reproduce easily in 2018? They were genius at it. Especially in developing the process.

It wasn’t easy back then. The Lumiere brothers worked to perfect Autochrome over the course of *decades*. Attempts by individuals working today in their kitchen or basement span mere months, and there have been a handful of successful reproductions in modern times.

Solving the technical challenges requires either decades of single-minded dedication and/or a deeply technical (scientific or engineering) background. Let’s face it, photographers aren’t scientists or engineers, so most photographers who wish they could make Autochromes likely wouldn’t even know where to start tackling the technicals. Not to disparage photographers at all ... it’s just a difference in how the brain is wired / trained for problem solving.

The reality is that Autochromes could be reproduced with a decent R&D budget in about the same amount of time it took Kodak to reintroduce Ektachrome, but there is simply no return on investment and thus no reason for an organization with the required resources and budget to recreate them.

 

[keenmaster486]

The reality is that Autochromes could be reproduced with a decent R&D budget in about the same amount of time it took Kodak to reintroduce Ektachrome, but there is simply no return on investment and thus no reason for an organization with the required resources and budget to recreate them.

What if there was, though? Would photographers buy Autochrome plates in 8x10 or 4x5? Why not? Of course it all depends on the pricing.

 

[Photo Engineer]

I doubt that there would be much market after someone saw the results. Autochromes scan very poorly.

It is wonderful as a historic exercise and a way to duplicate the past, but the "grain" is huge and the color and sharpness are both rather poor. Speed is low as well.

PE

 

[Nodda Duma]

What if there was, though? Would photographers buy Autochrome plates in 8x10 or 4x5? Why not? Of course it all depends on the pricing.

Realizing a return on investment means the demand and thus a viable market is there and so your statement answers itself.

The real question is: Are there enough photographers interested in Autochromes to convince some company out there to invest in bringing them back?

 

[J 3]

One interesting thing to think about - We tend to think of Autochrome as a lost WWI era process but actually it survived all the way until 1955. It wasn't very popular, but it made the transition to film stock and who knows what other innovations. That's late enough that in theory someone that worked at the plant may (unlikely) still be alive. More likely is some of this forgotten information may be squirreled away in a box of someones old belongings. Autochrome is dead, but it's more recent than one might normally presume.

As for what would sell, I think autochrome died because it couldn't match the color depth and sharpness of early Kodachrome 35mm. Back in the time, an insanely slow and limited process that produced a 3x4" fragile glass lantern slide from a heavy camera couldn't compete with a WWII era 35mm rangefinder loaded with Kodachome. Today however, digital has taken over the "cheap and easy" market. Anyone in traditional media is in it for some other purpose that doing what's simpliest. Grainy color can be seen as part of the look (and therefor be actually desired), or it can mitigated by the use of larger format. Same with color fidelity.

Spot on though IMHO is the "autochrome doesn't scan" remark. Films today are judged by how well they mix with digital processes, and you cant (I think) make a autochrome like look without the weird color space that makes it so hard to scan. I still wonder though. If someone offered an autochrome like process in glass or film (say same look but bumped up to ISO 25) rather than an exact duplication, how many people would overlook the scan issue?

 

[Photo Engineer]

Guys, be aware that the equipment and the method by which Autochromes were made still exist. In spite of that, the method of getting a useful Autochrome is very very difficult. It has been tried many many times since the end of production of the materials.

PE

 

[keenmaster486]

I have noticed there does seem to be a market, however small it may be, for hand-coated dry plates, at least. Maybe if ThePhotoChemist perfects his method, he could make some money selling small quantities or special orders.

 

[ThePhotoChemist]

I coated some screens with fresh emulsion last night, and woke up to... this! I'm not totally sure what to make of what happened exactly... 4 out of 6 plates, the emulsion flaked off as it dried. All of them seemingly had leaks into the starch, causing the dyes to bleed. I had noticed that several screens had developed some sort of "star" or "asterisk" like patterns, which I think may be the rubber layer lifting off the glass. However, I examined all my screens very closely before coating last night, and they looked nothing at all as poorly as they looked after the emulsion dried. I'm a little puzzled as to exactly what went wrong, but short of me accidentally dumping sulfuric acid in the emulsion or something, my working theory is that my second varnishes become brittle over some months and cracked.

Unfortunately, this means I've more or less trashed all the screens I made last year, so it's quite the setback. I still have a few plates that were starched and pressed, but never had a second varnish applied, so luckily I can test out different varnishes on them. I'd definitely be interested in hearing any recommendations on other second varnishes to try. So long as they dry clear and are not aqueous, they might be a good candidate.

I had success with an acrylic based driveway sealer - it dries hard and is water tight. However, it seems the gelatin doesn't like to stick to it, and flakes off as it dries. Does anyone have experience with using photographic emulsion on acrylic at all? Perhaps it could be subbed, or possibly dissolving damar gum may allow it to stick better? I guess tomorrow I'll make a control group and see if my emulsion is having trouble sticking to glass, too...

EDIT:

I also have to wonder, if I try out subbing (which I've never had to do before), would it hold up during the reversal bleach? Hmm...

EDIT 2:

This thread regarding liquid light seems to indicate that a particular solvent based acrylic varnish from Golden seems to allow for good adhesion.

 

[AgX]

One interesting thing to think about - We tend to think of Autochrome as a lost WWI era process but actually it survived all the way until 1955. It wasn't very popular, but it made the transition to film stock and who knows what other innovations...

As for what would sell, I think autochrome died because it couldn't match the color depth and sharpness of early Kodachrome 35mm. Back in the time, an insanely slow and limited process that produced a 3x4" fragile glass lantern slide from a heavy camera couldn't compete with a WWII era 35mm rangefinder

-) Autochrome was cancelled in 1935
-) its successors were rollfilms and only for a short period had to compete with Kodachrome. (Consider the post war situation in Europe)

 

[Photo Engineer]

Ouch, that was a bad loss with some seriously good looking screen coatings. Sorry to see that problem. It looks like it is multifold though. One is adhesion to the glass of all of the layers, and another is that the layers seem to repel. A third appears to be that the layers dry to different (or at different) rates. This latter assumes that some of the solvent of the wet layer wets the layer beneath.

PE

 

[Nodda Duma]

Emulsion doesn’t stick to acrylic at all, but you will have better luck coating onto polyurethane. Dip the plates in a thinned polyurethane solution (thin 50/50 with mineral spirits). Allow to set up a minimum of two days before coating.

Polyurethane will yellow with time, though I don’t know how apparent the yellowing in such a thin layer will be. Alternatively, blonde shellac may work but I haven’t tested that.

Cheers,
Jason

 

[ThePhotoChemist]

Ouch, that was a bad loss with some seriously good looking screen coatings. Sorry to see that problem. It looks like it is multifold though. One is adhesion to the glass of all of the layers, and another is that the layers seem to repel. A third appears to be that the layers dry to different (or at different) rates. This latter assumes that some of the solvent of the wet layer wets the layer beneath.

PE

Thanks for the kind sentiments. I found an old post of yours that may explain the problem with the emulsion adhesion. I have in my notes to add 0.4g of KBr to the emulsion as one of the finals. It occurred to me last night that typically I would skip this, since I never really got to test it out. In my recent attempt, I did not. I'm thinking I might re-run that recipe without the KBr in the finals and see if things look a little better.

Emulsion doesn’t stick to acrylic at all, but you will have better luck coating onto polyurethane. Dip the plates in a thinned polyurethane solution (thin 50/50 with mineral spirits). Allow to set up a minimum of two days before coating.

Polyurethane will yellow with time, though I don’t know how apparent the yellowing in such a thin layer will be. Alternatively, blonde shellac may work but I haven’t tested that.

Cheers,
Jason

I'm not sure about the polyurethane. I did make 4 screens with it last August (IIRC with your recommended 1:1 dilution). It coated very well, much less picky than the nitrocellulose stuff (it wasn't super weird about temperature, condensation, etc), and the gelatin adhered with no problems. I think one or two of them did yellow a bit, but I can't be certain. I didn't keep them labeled, so after this disastrous coating I can't really tell if they performed better or not. There were two that only had leaks into the edges, and not all the cracking/lifting -- maybe it was those? I think it's worth a second shot, with better notes this time!

 

[Nodda Duma]

Cool. Btw there will already be some amount of KBr in your emulsion after the washing phase (you always want some small amount to avoid having a surplus of silver ions). ..the added KBr just ensures a minimum amount and acts as an anti-foggant... it also reduces the emulsion speed some, so leaving it out you may get some additional speed but at the expense of increased base fog.

 

[ThePhotoChemist]

Cool. Btw there will already be some amount of KBr in your emulsion after the washing phase (you always want some small amount to avoid having a surplus of silver ions). ..the added KBr just ensures a minimum amount and acts as an anti-foggant... it also reduces the emulsion speed some, so leaving it out you may get some additional speed but at the expense of increased base fog.

Ah, gotcha. I always figured that was the mechanism, but never actually looked into it. I've always had a habit of reacting with KBr in excess during precipitation since my Lippmann days.

I'd never actually looked into the mechanics of varnishes/lacquers/whatnot before, since the Lumiere formula was temporarily getting me by. So, for those like me who don't really have much knowledge of such, here's what I found out this week.

The difference between varnish and lacquer: After the solvent evaporates, a varnish needs additional time to polymerize. A lacquer just has a bunch of junk dissolved in a solvent that sets up when the solvent dries, and can be redissolved and whatnot. Despite the term "Second Varnish", in this context the Lumiere varnish is actually a cellulose lacquer. Once the ethyl acetate (and in my case, amyl acetate) evaporates, the coating is good to go.

Polyurethane: I'm really warming up to this as a coating. I had always assumed that it had been around forever, and that if the Lumieres didn't choose it they probably had good reason. It turns out that it wasn't even created until 1937, and not in common use until much later. I've coated about 12 new screens with a few different variables. Most of them are still tacky even after sitting at room temperature for a few days, which is what prompted me to do this research. Due to the thicker coatings on some (1 tbsp / 20sqin, undiluted), it will likely be weeks until the coating is cured and ready to go on most of these. Just today I picked up some "Japan Drier", which has metal salts that will accelerate the rate of curing. I just coated plates with the polyurethane + Japan drier, so we'll have to see how that goes.

Pros: I know the emulsion will stick to it. I've tried it, and it's been proven to be water tight. Easy to coat, and does not cause the first varnish to wrinkle or lift from the glass

Cons: Will yellow when exposed to UV (though to be fair, UV will destroy the autochrome dyes too). Long cure time.

Acrylic Varnish: As mentioned earlier, my first attempt ended with the gelatin just flaking right off. I picked up a solvent based varnish from Golden, based on this super old forum post indicating that Liquid Light will stick to it. I've coated it on one screen that I messed up, so we'll see if my emulsion works or not. I think I still will try to mix in some damar resin I have in with the first acrylic driveway sealer just to see what happens, because it did make a really nice coating.

Mystery Varnish: I have no idea what type of varnish this is, but it was cheap. Slightly yellow after coating. Still tacky after a few days. We'll see what happens from here...

Alkyd Lacquer: Since this is not a varnish, this should dry quicker. I was worried that, because of the presence of alcohols, the dyes would bleed -- however, no dyes bled when I put a drop on a bare screen. I'll coat a plain glass plate to see if the gelatin sticks.

Epoxy: I think if epoxy is thinned properly, it could provide a good coating. I mixed up some with some terribly old epoxy I had laying around, and was successfully able to thin it with 1mL acetone / 10mL epoxy. It's still sticky to touch one day later, but that may just be because it's super old.

Polyester Resin: I figured I'd try this out, since the Photographic Emulsion wiki page mentioned that some polyesters were traditionally used as a substrate. I picked up some that is typically used for casting. I'm a little worried about how much it shrinks while it cures, but we'll see... And I can make Lippmann prisms with the leftover if it doesn't pan out.

Anyhoo, those are my thoughts on that. I welcome any input you all might have.

 

[Nodda Duma]

Have you tried shellac?

 

[ThePhotoChemist]

A loooooong time ago I tried it, before I had even made photographic emulsion. I remember it flaking off the glass as it dried, ripping up the starch with it. There might be some solvent based products, but I think the vast majority of them are all water/alcohol based. IIRC the Liquid Light guys say that it won't stick

 

[Nodda Duma]

Ah good to know

 

[AgX]

The difference between varnish and lacquer: ...

Wiki: "A distinction between spirit-drying (and generally removable) "lacquers" and chemical-cure "varnishes" (generally thermosets containing "drying" oils) is common."

Thank you for hinting at this. I was not aware of this.
Over here we do not make this differenciation in designation.

 

[ThePhotoChemist]

Wiki: "A distinction between spirit-drying (and generally removable) "lacquers" and chemical-cure "varnishes" (generally thermosets containing "drying" oils) is common."

Thank you for hinting at this. I was not aware of this.
Over here we do not make this differenciation in designation.

Same, here in the US the terms are typically used interchangeably, at least by laymen like me. It wasn't until my roommate (who is a furniture design student and knows a lot about this sort of thing) saw me heating my polyurethane plates "to speed up drying" did I find out that it wouldn't work that way. It will be especially confusing since the Lumiere term "second varnish" is actually a lacquer, at least in this context.

Here's a success I had last night. It's fairly dark and a little contrasty, so it pretty much has to be viewed with the plate directly against a light to make it out clearly. I was having some issues with yellow staining completely ruining the image during second dev. I think I was rushing the clearing/washing steps though, so I timed how long it takes to completely bleach the plate, and gave equal time to clearing and washing before second dev.

Here's an issue that I'm running into now. It takes a REALLY long time to bleach/clear/wash - about 50 minutes each! With my plates from Dec. 2017, I remember being able to visibly see the silver dissolving away over a few minutes. I've noticed that the same recipe, when used for normal glass negatives, has the same problem with fixing too -- it could take about an hour to completely fix the plate! Talking to Nodda Duma, one suggestion was to up the gelatin content, since mine was quite low (~2.8% gelatin). My gelatin is quite old too, so I've ordered some newer stuff too see if that's the issue.

As a small followup to my last post -- diluting polyurethane 1:1 with naptha seems to perform fairly well as a second varnish, but takes about 3 weeks to cure still. Undiluted polyurethane will take months to cure, so I have about 15 screens I won't be able to use until late summer, realistically. I tried about 8 other coatings with varying degrees of success, but I'm still working out some kinks, so I'll save my thoughts on them for a later time.

 

[Photo Engineer]

Like everything else, Naptha is a vague term. What is it?

PE

 

[ThePhotoChemist]

Like everything else, Naptha is a vague term. What is it?

PE

Too true! It's "VM&P Naptha" made by Klean-Strip. I tried diluting with odorless mineral spirits, however that created thousands of tiny bubbles that were trapped in the polyurethane, which causes some light scattering. It doesn't affect it much while I'm testing, but I'll be sticking with the naptha from now on.

Here's one of the plates with polyurethane diluted with odorless mineral spirits.