Making Commercial Color Separation Negatives of Transparencies for the Kodak Dye Transfer Process

[IB Photochemistry]

I have tested ratio of the base exposures for Kodalith pan mentioned in the shop manual, and I do find those values to be approximately correct using a 212 graphic arts exposing lamp at tap 4. One will need to first determine the proper red light exposure first.

The sensitometry of highlight masks is not as straightforward as sensitometry of other films. Specular highlights can have densities below 0.10 and most densitometers are not precise enough for 4 significant digits, so the curve trace can contain more error. Also highlights and specular highlights do not occur on the linear flat portion of the curve, so a gamma value or derivative of the curve trace, is not a constant throughout the entire curve. Many amateur publications speak of gamma of highlight masks, but that is the derivative of the flat portion of the curve and is not useful when dealing with the toe of the system since its not linear.

It is possible to characterize the development and exposure of highlight masks using the full curve of the transparency and the gamma of the flat portion, then reduce exposure by a certain amount to calculate the long range or “mid range” mask base exposure. The principle mask exposure increase factor will be needed here to obtain the exposure of the "mid range" mask. The highlight mask is few stops less (from memory) than the base exposure used for the long range ("mid range") highlight mask. Both the highlight and long range highlight mask have approximately the same dmax of between 0.6-0.8 DU, of masks made by Kodak affiliated professional labs. I should note that amateur publications speak of a highlight post mask as having dmax of 0.3 D, because they assume you will expose all of the masks with the separation negative at one time. There were other methods to determine the proper exposure and development of highlight masks beside this method, that were known in the industry and regarded as trade secrets.

It should be noted that Kodalith pan was packaged in groups of four sheets with interleaving paper between the film. The paper can cause fogging over time especially if the film hasn't been stored frozen continually. The packaging of this material is also problematic, since a two component box was used, with a small paper bag inside containing the film, light leaks can occur. Unlike Kodak pan masking film this bag is hard to completely flap over inside the box to create a good seal, at least from the boxes I have used.

 

[DREW WILEY]

Interesting.

When push cames to shove, I resorted to a special easel projection densitometer which is exceptionally accurate at low light levels, and within three decimel points. But I never actually needed that in relation to lith highlight masks. One can simply clean up the bottom of the curve plus base fog with a little Farmer's Reducer. But current Arista Ortho Litho has a distinct overall built-in stain, which won't clear. And back in the day, visual densitometry was often involved. Good enough for their needs. It's been a long time since I worked with any Kodaklith film. Tech Pan was more versatile; and there was also some kind of Euro pan lith film I briefly got ahold of, which I don't know the actual manufacturer of; it wasn't noted on the label.

 

[IB Photochemistry]

Interesting.

When push cames to shove, I resorted to a special easel projection densitometer which is exceptionally accurate at low light levels, and within three decimel points. But I never actually needed that in relation to lith highlight masks. One can simply clean up the bottom of the curve plus base fog with a little Farmer's Reducer. But current Arista Ortho Litho has a distinct overall built-in stain, which won't clear. And back in the day, visual densitometry was often involved. Good enough for their needs. It's been a long time since I worked with any Kodaklith film. Tech Pan was more versatile; and there was also some kind of Euro pan lith film I briefly got ahold of, which I don't know the actual manufacturer of; it wasn't noted on the label.

Have you made all the 3 types of highlight masks for dye transfer separations? I have and I might post my curves here.

Visual densitometry can not be used for fine control of this process, since it less precise than three digit precision densitometers. The human visual system can't differentiate highlight densities very well. It can be done with the common electronic densitometers reading up to 3 significant digits.

Kodak Technical Pan was never used for highlight masking in industry! A few people, Bob Pace (deceased 2006) and Tom Rankin (deceased >25 years) might have suggested tech pan as a highlight masking film for amateurs since its easier to use and protects their trade secrets. In the draft shop manual partially written by Tom Rankin I have posted to this site, one can see Tech pan was not used. In the mid 1990's they used Agfa Litex Pan P911P, from my source. Tech pan was used for occasional color negative separations, and color isolation masks. I know of no commercial labs that used Tech pan for highlight masks because its toe is very small and can't invert the toe of the transparency matrix system. It has a rather flat curve for most developers at high contrast. There is a chance it could be used for long range highlight masks since some of highlights go onto a more flat portion of the curve, but doesn't have much of a toe. The long range mask is for spacial modulation of the principle masks, not to the modify the characteristic curve of the system. The highlight and specular masks do that.

Kodak Contrast Process Pan and Contrast Process Ortho might be more preferable for making highlight masks aside from litho films. Contrast process pan has a bit of a bent curve and can probably be used for making “mid range” masks, but I don't think it would work as well for highlight masks. It doesn't have a very contrasty toe so its effect on the characteristic curve wont be as great as Kodalith pan/Litex Pan. There were a few commercial labs that used Contrast Process Ortho and possibly Contrast Process Pan for certain types of highlight masks.

 

[DREW WILEY]

Yes, I do know people who specifically used Tech Pan for DT highlight masking. It wasn't just hypothetical, although I am aware of those what-if published cases as well. I used it for all kinds of things except general photography. My biggest highlight control need was in reference to Cibachrome, where it's just the specular highlights involved. Second-tier masking would be done differently in that case. And frankly, there a plenty of times that the most efficient specular highlight mask is simply to use a fine point Sharpie pen on a registered sheet of frosted mylar
(large format original film of course). The advantage of Tech Pan is that it was panchromatic, readily available, had its own suite of developers, and didn't blotch up like Kodalith etc with A&B lith developers.

Tech Pan would be an awful separation negative film.

Despite being an informative and interesting conversation, we're still going around in circles because all of these films are past, and not currently available.

 

[Carnie Bob]

Yes, I do know people who specifically used Tech Pan for DT highlight masking. It wasn't just hypothetical, although I am aware of those what-if published cases as well. I used it for all kinds of things except general photography. My biggest highlight control need was in reference to Cibachrome, where it's just the specular highlights involved. Second-tier masking would be done differently in that case. And frankly, there a plenty of times that the most efficient specular highlight mask is simply to use a fine point Sharpie pen on a registered sheet of frosted mylar
(large format original film of course). The advantage of Tech Pan is that it was panchromatic, readily available, had its own suite of developers, and didn't blotch up like Kodalith etc with A&B lith developers.

Tech Pan would be an awful separation negative film.

Despite being an informative and interesting conversation, we're still going around in circles because all of these films are past, and not currently available.

I owned a Cibachrome Lab back in the day starting first with enlarger base work and with the higher quality grade Ciba material , we did masking techniques. On was a highlight mask that had a two step method so that there was separation created with a blocker that gave a superior mask that not only reduced contrast in the highlights so you could see detail when printing but also provide modulation..
Much like printing highlights in silver I will flash the paper, then burn with a lower filter but also burn with grade 5 filter to darken within the highlights any areas with some density, this creates a much better highlight rendition.

Both methods are different in workflow but the end goal is quite the same.

Today I do not do any negative or positive masking but I do use the second method when printing silver daily , so the above is my attempt to add to this conversation.

 

[DREW WILEY]

Thanks, Bob. There are so many routes to masking!

 

[IB Photochemistry]

Yes, I do know people who specifically used Tech Pan for DT highlight masking. It wasn't just hypothetical, although I am aware of those what-if published cases as well. I used it for all kinds of things except general photography. My biggest highlight control need was in reference to Cibachrome, where it's just the specular highlights involved. Second-tier masking would be done differently in that case. And frankly, there a plenty of times that the most efficient specular highlight mask is simply to use a fine point Sharpie pen on a registered sheet of frosted mylar
(large format original film of course). The advantage of Tech Pan is that it was panchromatic, readily available, had its own suite of developers, and didn't blotch up like Kodalith etc with A&B lith developers.

Tech Pan would be an awful separation negative film.

If these were professional labs making the claim that they used Tech pan for highlight masks, they’re probably lying. Amateurs, and other kinds of DT users might have used Tech pan as a highlight masking film. Commercial DT labs used Tech pan for occasional red light color negative interpositives (due to its sensitivity at 690 nm) and color isolation masks. Tech pan isn't a good separation film for transparencies, being at gamma 65-90. Sometimes Separation Negative type I and II will provide proper contrast with the red color record at the extreme end of its spectral sensitivity (~650 nm), at other times it does not. I myself have not tried this yet with color negative films.

Highlight masks are not just of importance for DT related processes, as some can be used for reversal printing, duplication, black and white printing, and color negative printing. This is a valuable photographic darkroom tool, that can improve print quality.

Making a highlight bump mask with a fine pointed marker can certainly be done, and has been used before in the DT field for selective specular masking. Usually ink from Sharpie markers isn't very uniform in density, it may need to copied onto something like LPD4 (a reversal lith film) or kodalith ortho to make the final mask. Specular masks were made photographically and hand made masks were used in only some select cases.

In reversal printing the highlight mask curve needs to go the opposite direction on the characteristic curve. The first highlight mask would be made off of a transparency then a gamma 1 negative would be made of it. The reversed highlight mask would be exposed in a registered carrier to expose only highlights, then the mask would be removed and the transparency would be exposed normally.

In negative to positive printing highlight masks can be made from either reversal lithographic film or from an interpositive. In each case the high contrast toe is utilized to partially linearize the characteristic curve of the system. Tech pan is not well suited for this either.

The processing of lithographic films can be more challenging than typical pictorial films. Mainly they develop faster, and are prone to uneven development. I have successfully processed Kodalith Pan in trays using a small amount of docusate sodium surfactant (Aerosol OT) in the developer, about a 1/10 ml of 20% stock solution to the tray volume. Old film may require some anti-foggant as well.

Despite being an informative and interesting conversation, we're still going around in circles because all of these films are past, and not currently available.

The films used for commercial Dye Transfer separations were suited for that application, while most films currently in production do not work well for this. It is essential that people understand how these were intended to be used with commercial DT separations, since most of that information wasn't published and was selfishly guarded. Also these films can be found occasionally on websites such as eBay, making it possible to test these films in a separation process.

While there are people who have claimed to used other separation and masking films to make DT separations, none of that has been published. I strongly suspect if modifying the process using pictorial films and other types of masking films, that the result will either be inferior to the old process or more complicated and more difficult to control. It certainly would not be any better than the old films.

 

[DREW WILEY]

They aren't lying. I won't mention specific names because I don't want to drag them into a frivolous food fight. Nor am I going to keep locking horns with you over the allegations that either 1) Current films options for either masking or separations are somehow inferior - doesn't matter anyway, since long discontinued films aren't a viable choice going forward anyway); or, 2) That all of this involves deep dark conspiratorial secrets - yeah, there were undeniably certain instances of that, along with some ornery personal rivalries; but in the main, basic information has been openly accessible for quite awhile.

Personally, I can't go back and repeat my experiments with Tech Pan because I sold off my whole stash of 8x10 to someone else a couple years ago who needed it more than I do. Most of my color printing going forward is RA-4 based, because I've taken that to a higher level than most people are aware of being possible in a optical printing context.

Generating color separations from color negatives is a bit of a headache because the contrast has to be significantly boosted somewhere in the overall procedure. Ideally, I'd do the double-negative technique using TMax for both the interpositive and finished negative. But since I had a bunch of 8x10 Ortho litho laying around, and just for fun and curiosity, and for sake of being on the cheap, I used some of that for the second step. Yeah, it's a pain in the butt. But only the primary interpositive needs to be on a pan film. And I was not aiming for a perfectly matched set anyway, like for DT printing, but just a RGB set useful for different renditions of black and white print finals - that was certainly a worthwhile use of my time.

Of course, when making masks or more serious interpositives from color neg film, I null out the orange mask as well as any uneveness in the black and white film spectral sensitivity curve itself. I do have that procedure fine-tuned. But off set printers and carbro printers had all that figured out long ago; and I specific manuals from that era which are fun to read, but outdated as per currently available materials. I don't think much conventional DT printing itself needed complicated separations from color negs , since there was the more straightforward option using Pan Matrix Film instead.

 

[IB Photochemistry]

They aren't lying. I won't mention specific names because I don't want to drag them into a frivolous food fight. Nor am I going to keep locking horns with you over the allegations that either 1) Current films options for either masking or separations are somehow inferior - doesn't matter anyway, since long discontinued films aren't a viable choice going forward anyway); or, 2) That all of this involves deep dark conspiratorial secrets - yeah, there were undeniably certain instances of that, along with some ornery personal rivalries; but in the main, basic information has been openly accessible for quite awhile.

So basically Drew never actually made these kinds of highlight masks himself, and doesn't have the actual sensitometric data of these films that were used. You just need to trust him that Tmax and Tech pan were used in commercial DT labs based on what some people (now deceased) have claimed. I have both actual data from the labs that wasn't published and my own data, and they converge. From my research, Tech pan was not in common use for most commercial Dye Transfer labs, except for its other uncommon uses in DT. I am interested in the actual methods, procedures, documentation, and materials used in the commercial Dye Transfer industry, not what others believe was used based on their own biases.

My reasoning for using old materials is they work the best for what they were designed to do. There are no “modern” films that work well with one possible exception. Drew seems to have this notion that “going forward” old materials aren't viable. The materials that exist are very rare and mostly old Kodak materials. Many of which I have myself.

There is a separation motion picture film actually still in production. The EASTMAN Fine Grain Duplicating Panchromatic Negative Film 2234, is essentially like Separation Negative Type I and II for positive motion picture prints. The datasheet looks very similar to Kodak Separation Negative films, in terms of gamma range, tonal linearity, spectral sensitivity and, MTF curve. I wouldn't be surprised if there was some internal masking built in as well. I think it would work well if cut into sheet sizes. It comes in 35 mm and 65 mm rolls. Making contact separations with 120 film would be possible with this material.

There a few individuals who have coated a matrix film and transfer paper recently but that is not available for sale to the public. (And some of those handful of people are using it by optical enlarger.) I can't speak too much about that project on this platform for various reasons. Its important for me to raise interest in this among the younger generations to experiment with masking and color separation methods.

Generating color separations from color negatives is a bit of a headache because the contrast has to be significantly boosted somewhere in the overall procedure. Ideally, I'd do the double-negative technique using TMax for both the interpositive and finished negative. But since I had a bunch of 8x10 Ortho litho laying around, and just for fun and curiosity, and for sake of being on the cheap, I used some of that for the second step. Yeah, it's a pain in the butt. But only the primary interpositive needs to be on a pan film. And I was not aiming for a perfectly matched set anyway, like for DT printing, but just a RGB set useful for different renditions of black and white print finals - that was certainly a worthwhile use of my time.

Color negative film has a gamma of about 0.6, and Tmax film can probably can't go beyond a gamma of 0.7. Assuming you can effectively isolate all the dyes your interpositive will have a gamma of (0.6 dye image gamma) X (0.7 Tmax film gamma) = 0.42. Making the print will require more contrast to make a normal print.

Many master black and white printers used Tech Pan to make the interpositives of color negatives. Tmax (a poor separation film for color work) doesn't have sensitivity at 690 nm and usually can't go above a gamma of 0.7 without other problems.

Of course, when making masks or more serious interpositives from color neg film, I null out the orange mask as well as any uneveness in the black and white film spectral sensitivity curve itself. I do have that procedure fine-tuned. But off set printers and carbro printers had all that figured out long ago; and I specific manuals from that era which are fun to read, but outdated as per currently available materials. I don't think much conventional DT printing itself needed complicated separations from color negs , since there was the more straightforward option using Pan Matrix Film instead.

I'm not sure what Drew means by “uneveness in the black and white film spectral sensitivity curve itself.”? The spectral sensitivity curve is a property of the film itself, its generally not effected by development. You are not likely to sensitize Tmax 100 down to 700nm; most of the sensitivity is fixed at manufacture.

The indoaniline cyan dye spectral band in color negative film may have some crossover into 650 nm. Since the spectral integration is only on a side band it will not give the full contrast, that can be obtained at 690-710 nm region. The red separation will be much flatter than the other two.

DT from color negatives still required correction of the printing dyes. So assuming you have a good set of interpositives those are only corrected for the color dyes in the negative film itself, additional correction is needed to bring the print to Equivalent Neutral Density standard.

Sometimes highlight masks were made off of the positives, though not as important as highlight masks for color transparencies.

 

[DREW WILEY]

You're twisting my words. I've made all kinds of highlight and other masks, and have experimented with various methods and films for generating tricolor separations which I certainly wouldn't recommend as ideal to others, and only used myself for "what if" experimentation. And I'm getting a bit tired of your "know it all" attitude, especially since I've been in communication over the years with DT veterans who have rather different approaches to the same kind of problems. And I most certainly don't appreciate you implying these helpful people are "lying" just because you find their specific proven methodology doesn't comply with your own hypothetical version. In fact, there's not a lot of difference from making highlight masks from Tech Pan than using the same film in 35mm for title slides, which was once commonly done, including by me.

As far as panchromatic film sensitivity goes, just try to overlap the spectral distribution, one film to another; they don't necessarily match. A dip in green sensitivity is there, but not to the same extent. Red and blue sensitivities also differ.
Therefore, if you expect ideal tonal representation when generating a mask or interpositive, you need to balance out those little hills and valleys, as well as null out the specific orange mask inherent to color neg film, if that is involved too.

If you think you can leverage a special volume sheet cut of 2234 Eastman film, more power to you. But where is this all leading anyway? As much as I myself prefer an all-darkroom all-film workflow, the future of color separations in any commercial sense is going to be digital. That bridge was crossed quite awhile back. And how many hobbyists are going to be able to afford significant multiples of now expensive sheet film per individual image, along with matrix film and all the time and space to deal with it? Where's your market? Those who make gum prints and casein and color carbon generally aren't that fussy in terms of color repro.

 

[Lachlan Young]

I wouldn't be surprised if there was some internal masking built in as well.

Colour neg camera film is already inherently masked for contrast and colour. The logical outcome of your argumentation is that Separation Neg 1 & 2 weren't inherently masked either.

You are desperate for conspiracy, rather than some people (who had a vested interest in dye transfer staying alive) trying to encourage amateur/ home darkroom printers to work with the process using materials that were more readily available over the average camera shop counter than graphics arts films that had a higher barrier to entry (even if the per sheet cost was lower). None of the Agfa GA materials had or have any particularly magic properties (other than in areas like relative cost and availability).

 

[IB Photochemistry]

Colour neg camera film is already inherently masked for contrast and colour. The logical outcome of your argumentation is that Separation Neg 1 & 2 weren't inherently masked either.

You are desperate for conspiracy, rather than some people (who had a vested interest in dye transfer staying alive) trying to encourage amateur/ home darkroom printers to work with the process using materials that were more readily available over the average camera shop counter than graphics arts films that had a higher barrier to entry (even if the per sheet cost was lower). None of the Agfa GA materials had or have any particularly magic properties (other than in areas like relative cost and availability).

Ektacolor Negative film is masked for only its OWN dyes (derived from CD-4 developer), not the dyes for another system. A color negative is essentially a set of three direct color separation negatives. When in its printed onto type C paper, the paper's emulsion utilizes a masking system for color correction for its own dye system. In RA-4 the dyes are formed from oxidized CD-3 developer reacting with different types of couplers.

You misunderstood what I said regarding internal masking with Eastman type 2234 negative film. The internal masking occurs during development, which alters the spectral sideband contrasts. I'm saying there is a possibility that this system was utilized in the motion picture market as well. I would be interested to know if anyone here has worked with Eastman 2234 or similar film stocks in the motion picture industry.

 

[koraks]

When in its printed onto type C paper, the paper's emulsion utilizes a masking system for color correction for its own dye system.

That's a very awkward way of describing how RA4 paper works. But it's offtopic.

 

[gorbas]

Very intriguing discussion!
Interestingly, nobody mention Ctein, one of the last dye transfer printers, still alive in USA.
By now, he must used all of his stash of dye transfer materials?

 

[koraks]

By now, he must used all of his stash of dye transfer materials?

He discarded is remaining dyes several years ago (10? 15?) I think he's still selling some remaining prints. His writings are still accessible and quite interesting, although I believe they don't go quite this deep into the different masks involved.

 

[gorbas]

He discarded is remaining dyes several years ago (10? 15?) I think he's still selling some remaining prints. His writings are still accessible and quite interesting, although I believe they don't go quite this deep into the different masks involved.

In this discussion I was surprised about number of masks required to make for dye transfer. I did project with colour separation for my graduation thesis in 1989 and I got interesting result working basically at home darkroom and using ordinary photography supplies available to me. But this level of dealing with masks is way above I ever imagined.

 

[DREW WILEY]

Ctein recently relocated to Ireland. He already sold his house here, where I visited him a few times. I purchased most of his remaining dyes about over ten years ago, and still have them. He want just enough on hand to cover his limited remaining stash of Pan Matrix Film usage. He was not a conventional DT printer starting from chromes and color separation negatives, but went the far less common alternate route starting with color negative shots. Far less masking is involved with that. All his recent work is in inkjet. Some of the things he published about DT techniques were hypothetical and not really ever tested. But he was good enough to make much of his living specializing in dye transfer commissions. Now he is delving heavily into Science Fiction writing.

Ironically, one of the largest DT labs almost completely circumvented masking. But the primary individual involved was one of those who did rabidly guard his trade secrets and downright bitterly hated any potential competitors. Only in a fit of contempt did he blurt out to me what some of those primary secrets were, just to make me feel uninformed; but I'm certain that few have even heard of that particular line of technique. I won't repeat either the details or the name here. But the logic of the workflow is sound, if one can afford all the relevant chemical supplies, which few could even back then.
They used different sources than Eastman Kodak.

If one wants to attract new devotees to DT, they need to simplify the workflow and accessibility to needful ingredients as much as possible, not overcomplicate it with technical minutiae of only arcane interest.