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Photo Engineer
08-11-2007, 09:12 AM
Chemically modified gelatins such as phthalated gelatins were not used (AFAIK) in Dye Transfer materials. The modified gelatins may have been, but to this point, they have never been mentioned in this thread. I have certainly not commented here on modified gelatins before. They certainly have different isoelectric points depending on the degree of modification. They were used in the 50s - 70s approximately, for ISO washing of emulsions until ultrafiltration replaced it as the preferred method. I have mentioned this elsewhere many times. I have, as I said, never mentioned them in connection with DT materials.

If they were used, they certainly did not help Technicolor as they described to others the need to segregate coatings into the 3 classes I describe. If Kodak were modifying the swell through manipulation of isoelectric point, I would think they would do a better job, as we had many levels of modification expressed as percent modification. This would have allowed a very fine level of control and a more consistent product.

Modification causes the gelatin to coagulate and then redisperse. I teach this method to my students in the workshops I conduct. Over acidification however, will coagulate the emulsion permanently, and therefore would be a precaution to take in using such a film in dye transfer as it would then produce an unusable (unswellable) matrix. It is therefore advisable to never go below a pH of about 3.5.

The curve I posted above is typical of all of the bone gelatins that are in current photographic use. My work at Kodak included testing of gelatin swell as a function of hardening level using a swellometer. We were trying to find the optimum level of the new hardener. I have mentioned that also here and elsewhere.

I point it out to indicate that there are many confidential reports and experiments that exisit not known to the general public.

In any event, the acid base cycle in the DT process is, in part, present to remove metal salts from the emulsion. The presence of these metals would immobilize the dye and prevent diffusion. It is also used to 'exercise' the gelatin and keep it supple during the imbibition process.

It is an intersting note that the depth penetration pigment is water soluable. Carbon black is not water soluable. It may form a dispersion that can be suspended in water, but is not in any way soluable in water itself. As for removing alkali from matrices, there was no alkali in the matrices that I know of. The matrices were merely soaked in alkaline solution and acid solution to 'temper' the swell, and the alkaline soak was used to remove residual dye trapped in the matrix. A common reason was formation of a calcium salt from retained calcium and that is why there was a pre-treatment.

The number of prints possible from matrices was due to the improved gelatin technology as it developed from the 40s onward. I have mentioned this before here.

PE

Photo Engineer
08-11-2007, 09:37 AM
In all of the emulsion formulas I have described, I have used the same gelatin for precipitation and for coating, unless I describe ISO washing where I use phthalated gelatin.

I should mention here that before phthalated gelatin was used, and now in modern times, two different gelatins were often used during making and coating.

One gelatin was used for precipitation and another was used for 'make up' commonly called 'make up gelatin'. These did not have to be the same gelatin types. The ratio of silver halide to the total gelatin quantity was different in different products and therefore the make up gelatin could be present in different ratios.

In addition, polymers, humectants and other ingredients were used to extend the gelatin for one reason or another. Polymers included poly vinly alcohol and poly vinyl pyrrolidone and humectants included glycerin and sorbitol. The humectants often washed out during coating.

There was also the comment about modification. In the early days before ISO wash, the term modified gelatin was often applied to gelatins that were either purified or had the allyl thiourea removed the so called 'oxidized' gelatins or nowdays 'photograde' gelatins.

Also, there were methods called grafting in which certain chemical groups were grafted onto the gelatin. Phthalation was just one example.

In many cases, with makeup gelatin, these methods were applied to change viscosity and therefore allow coating at higher speeds. It should be noted that sulfonic acid organic compounds increase viscosity and tartrazine used in Matrix film is such a compound. It therefore would increase the viscosity of the gelatin and depress the chill point of the gelatin. This might, in itself, have dictated the actual coating conditions and pre-preparation of the gelatin.

I have coated sulfonic acid dyes with great success, but my first tries resulted in a disaster due to the above modifications of viscosity and chill set point due to miscalculations on my part. I ended up with a putty knife helping the coaters clean out the mess from the chill section. I have also 'mordanted' dyes in gelatin by using calcium and magnesium sulfates.

PE

Photo Engineer
08-11-2007, 02:49 PM
If you look at USP 4409315, you will find listed several sets of modern azo dyes making up cyans, magentas, and yellows.

These sulfonic acid dyes were to be used in the 3000 speed Kodak instant film that never was. They were mordanted to a quaternary salt cationic mordant along with Nickel ion which complexed with them to achieve stunning color purity and image stability.

In this patent there is considerable discussion about ETA development and the theory behind the cross oxidation etc. that I brought up elsewhere. Along with this is a long list of patents that describe other aspects of ETA and dye transfer. This is where I basically learned how to design ETA developers.

My point here is that to build an instant imaging product that is integral, the development rates and diffusion rates of everything in the package must be known to a very fine degree to prevent color shifts, high dmin and a host of other problems that might arise. This involves the construction of timing layers that open or close exactly at the right time regardless of temperature or age of the coating(within reason).

My associates and I, in working with a large group on this had to understand how to move dyes, developers, alkali and other ingredients around within this tiny package and orchestrate things to work together or the image was useless.

This work evolved out of modern chemistry and physics and the modern mathematical models of dye diffusion and interaction with gelatin that I have been discussing. Comparing the actual in-house internal information at Kodak to what was published in 1940 or thereabouts is like comparing the math of Einstein to that of Witten. There was a lot learned in the last 60+ years regarding development and diffusion as well as dye-gelatin interactions.

I hope that those of you who wish to see the complexity of a real dye diffusion transfer process will take a look at this patent. It will show you where Dye Transfer went to and how it evolved within Kodak (and Polaroid).

PE

Photo Engineer
08-15-2007, 02:54 PM
At our lunch of former Kodak engineers and friends at George Eastman House today, I showed our group a DT print of Jim's, one of the 3 he has given to me.

Our group included a former engineer who worked with DT materials.

I also showed some color prints of Jim's coating machine and the methodology used in operation.

The group were impressed with his results as a photographer, a lab operator and an engineer for desiging the coater and I wish to pass on their commendations to Jim for preserving this process for us all.

Thanks Jim from our little group. Good job!

PE

CRhymer
08-15-2007, 03:34 PM
At our lunch of former Kodak engineers and friends at George Eastman House today, I showed our group a DT print of Jim's, one of the 3 he has given to me.

Our group included a former engineer who worked with DT materials.

I also showed some color prints of Jim's coating machine and the methodology used in operation.

The group were impressed with his results as a photographer, a lab operator and an engineer for desiging the coater and I wish to pass on their commendations to Jim for preserving this process for us all.

Thanks Jim from our little group. Good job!

PE

That is very positive. Good news. I am not surprised, but it needed to be said for all to see.

Cheers,
Clarence

dyetransfer
08-16-2007, 10:41 AM
The group were impressed with his results as a photographer, a lab operator and an engineer for desiging the coater and I wish to pass on their commendations to Jim for preserving this process for us all.

Thanks Jim from our little group. Good job!

PE

Thanks for you kind remarks, Ron. Also thanks to your fellow Kodak associates. It is refreshing to hear something positive these days.

Regards - Jim

CBG
08-18-2007, 09:03 PM
Hello Photo Engineeer,

You are more appreciated than you will ever know - which unfortunately makes you a prime target for trolls and the like... if you want to see a trail of the behaviour of trolls elsewhere, look about for a troll who seems to have popped up first as: Mike Scarpitti - presumably a real name. After being banned from various bulitin boards for intollerable behaviour, it is said he then showed up as: Hans Beckert - his first fake name.

After being banned as HB, one Ladislav Lowenstein, III appeared - evidentlty a second fake name. It seems all the many faces of Mike are now banned everywhere, a fate I believe might be more broadly applicable to tormentors of the righteous makers of photographic materials, i.e. PE.

Note he deprectates the best liked, the most sacred of the sacred cows, items he knows will cause insult.

A great faux latin saying: "Illigiterum Non Carborundum"; don't let the bastards wear you out.

Best,

C

Photo Engineer
08-27-2007, 11:15 AM
I have found more on Pan Matrix Film on the DT forum and wanted to bring this thread up to date with information on the processes mentioned there.

Kodak made a series of products or experiments based on direct reversal emulsions. These were referred to as Reversal "F" and Reversal "P" based on the emulsion chemistry involved.

Apparently, Louie Condax had some film made using one of these emulsions to make a trial Pan Matrix Film or a Matrix Film. At the time this was done, the emulsions were being used in an experimental Type "R" paper (sold in Europe for a time but never in the US) that was to be called Directachrome. The emulsions were also used in Kodak PR-10 instant film.

The required emulsions would therefore have been readily available for experimentation within Kodak, but alas the DT product was never sold.

As for a reversal process for Matrix Films, I have never heard of it being done, but I assume it can be. On another topic, a process that reverses the hardening is very difficult, if not impossible to achieve. It has less image discrimination than the hardening process done by tanning developers and therefore has a tendancy to decrease quality.

I have no information on either of these latter two except to know it might be possible, and that there are inherent problems in both approaches.

PE

dyetransfer
11-16-2007, 10:42 PM
Photographer's Formulary is now selling cut sheets of 0.007" Melinex 582 polyester stock. This is the cut from the roll I used when developing my matrix film. This is the last remaining stock of this particular film, and it is the only substrate suitable for coating matrix film because the subbing layer doesn't pick up dye stain. It is coated with a great subbing layer on one side, and an antistatic layer on the reverse side. Works great with any gelatin emulsion. Get it while it lasts!

Regards - Jim Browning, the Dye Transfer Guy.

wildbillbugman
09-01-2008, 02:22 PM
"Use a black dye in place of the Tartrazine"
Hi Ron, Would Pylum "Acid Black#1" be appropriate?
Th at is the only black dye I happen to have on hand.

Photo Engineer
09-01-2008, 02:41 PM
Bill;

I really don't know, as I have not tried it. Sorry. It probably will if it dissolves in gelatin without harming its gelation effects, and if it is harmless towards the emulsion.

PE

dyetransfer
09-02-2008, 01:50 PM
Hi Bill - you could also use a black pigment. I suggest trying some artists' water color paint. You can get it in small tubes, one tube should make lots of film. You would have to experiment with the concentration to maximize your exposure, while avoiding excessive depth of exposure. Also, you may find that the addition of a pigment or a dye changes the curve a bit, which may work for or against you.

Regards - Jim

Photo Engineer
09-02-2008, 02:33 PM
Well, I do know one thing about pigments. Those made with carbon black or "soot", are harmful to emulsions. I cannot remember details, but they either cause fog or restrain development. All I remember is that carbon "powder" must be specially purified for photographic work.

Carbon black is usually formed by incomplete burning of oils or tallow or paraffin. These materials often contain sulfur compounds that adsorb to the carbon granules and must be purified out of the material before use.

We ran into this in PR-10 pod and film pack making. The carbon black was doing nasty things to the film pack and goo.

PE

wildbillbugman
09-07-2008, 04:45 PM
Hi Ron,
Are these dyes best disoved in something prior to adding them to the emulsion? Other procedures I have read call for dysolving the dyes in methanol, making a stock solution.
Thanks,
Bill

Photo Engineer
09-07-2008, 05:33 PM
Make solutions of 100 mg / 100 ml of alcohol (methyl, ethyl or iso propyl in order of preference). That is 0.1%.

Store in a refrigerator.

Use at about 10 - 100 mg of dye / mole of silver depending on grain size. Amount goes up as grain size goes down. I would start at 50 mg/mole.

Add after the emulsion is melted, and hold 15 minutes at 100F, then add hardener and spreading agent.

Read the manual. :D

PE

wildbillbugman
09-08-2008, 12:14 AM
Read the manual. :D

PE[/QUOTE]

What manual? Did I miss a handout at the workshop? Or are you reffering to this Forum?
Bill

Photo Engineer
09-08-2008, 09:01 AM
There is a section in the workshop notes that covers this. They are about 50 pages long, so you may have to hunt a bit, but it is under the camera speed orthochromatic emulsions.

PE

Kirk Keyes
09-08-2008, 10:53 AM
The Manual -

You mean Bruce Kahn's class notes?

wildbillbugman
09-08-2008, 11:19 AM
Who the heck is Bruce Kahn? Kirk, Do you know what he is talking about?

dwross
09-08-2008, 11:46 AM
Who the heck is Bruce Kahn? Kirk, Do you know what he is talking about?

Hi Bill,

I was feeling a little put upon for a second. " Manual? What manual!? Our workshop didn't get a manual." :) But I think Kirk is right that Ron means the Kahn class notes. Ron emailed those to us after our workshop. If you don't have them, I'll send you a scan of the pages on dyes, but they almost certainly won't do you any good. They are just screen shots (or a facsimile) of what looks like Powerpoint bullets for a lecture.

Denise