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AgX
04-30-2007, 08:29 PM
It would be interesting to hear more about the successor emulsion [to Technical Pan], which I am anxious to test one of these days.


Successor? Did I miss something?

Photo Engineer
04-30-2007, 09:19 PM
To Max;

I am trying to get a reference. The patent was pre 1975 and therefore is difficult to search for on the patent site. I know the inventor, but not the patent #. IIRC, I had the internal Technical Reports but turned them in when I retired. Sorry.

AgX;

In the 40s Kodak certainly had high speed films. So did Agfa. At the end of the war, Kodak applied gold to their high speed films, effectively doubling speed so that 50 speed films became 100 speed. Therefore, at the end of the war, Agfa was overall a bit slower or grainier than Kodak.

The Kodak technology was unique to Kodak and Agfa's was gold salts. As a result, Kodak gained the additive effects of their own and Agfa technology effectively giving them a lead. I might add that Ilford and others probably benefited as well.

Kodak now is using 2 electron technology which is akin to the advance of gold in the 40s. There are so many more, I just cannot describe them here, but one that comes to mind is the Kodak supersensitization which is the addition of an organic chemical which doubles or quadruples speed. This was known in the 40s. Unfortunately, these esoteric chemicals are only really known in internal documents.

I think it fair to say that anyone who claims otherwise, that they know the details of this and is not from Kodak, is either incorrect or has highly confidential information. Small pieces of this, of course, have been published.

PE

rmazzullo
04-30-2007, 09:40 PM
Hello all,

I have to admit, this is somewhat perplexing. I was under the impression from my recent research that rudimentary feedback control was a recent (very late 70's, early 80's) innovation at Kodak, with full control not coming until much later. There seems to be conflicting information being presented here. If Tech Pan was made earlier than the late 70's, was Tech Pan made with or without control?

Thanks,

Bob M.

Ryuji
04-30-2007, 11:48 PM
Bob,

The conventional double jet technique with feedback control to maintain pAg was published by AGFA people in 1964. I'm going to steer clear of Kodak-relate info for now due to some agreement with a few people, but this type of emulsion making setup (commonly called controlled double jet) was in use in research labs of Fujifilm already in 1960s. As I said before, it took a decade or two before this new technology saw practical use with advantage in commercial plant scale. (That is, even with the fancier machine, the engineers couldn't make better emulsion for some time, compared to the old-fashioned method.)

Ryuji
05-01-2007, 12:06 AM
Dear AgX,

Did you know that I have a domain name AgX though it's not in very active use right now?

Anyway, I have a lot of things to say about your Koslowski post and response thereto, but I will limit my focus due to some agreement that is in effect.

The stabilizer I mentioned before, which you also mentioned, is 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene, commonly called TAI among emulsion engineers. (Note: this compound was called 5-methyl-7-hydroxy-triazaindolizine at that time, but these names refer to the same compound.) There are several derivatives of this compounds. This compound was the work of Birr at Wolfen in late 20s or around 1930. Fast AgBr or AgBrI emulsions that received optimal amount of chemical sensitization develop fog very easily during storage, so stabilizer is needed, but many antifoggants known then (e.g., 1-phenyl-5-mercaptotetrazole, commonly called PMT, and many other nitrogenous heterocycles with thiol group attached to the heterocyclic ring) severely decreased the photographic speed of such emulsions. So Birr was working on a LOT of organic compounds that have good stabilizing actions on emulsions but with minimal of speed penalty. He was a master of heterocyclic compounds at that time, and he found TAI and he also continued his entire career in photography in research of mechanism of how these compounds stabilize emulsions.

In the latest emulsion making processes, the role of "stabilizers" is not limited to post-digestion stabilization but they are more proactively used to control the crystal growth, specific location of sensitization within each grain, etc.

AgX
05-01-2007, 02:58 AM
Dear Ryuji,

No, I did no general search for `AgX´. Only at Apug. (Here is another AgX around; he saw some light though…)

Thanks for naming this stabilizer. I only knew its structure, its `family´ name and its Agfa internal name. I did not dare trying to name the structure.
To my information it was in the late twenties that by two other Agfa people (Mathies/Wendt) the predecessor of that stabilizer was found, a sulphur containing heterocycle. Birr came to Agfa only in ’34 and found TAI in 1937 (after the presentation of the New Agfacolor film).
But I admit finding these dates is difficult and the results are not necessarily trustworthy as long one did not see the original documents, which I did not.
All this is getting very special and I guess annoying to some people and I sometimes think it would be better to have a special historic forum, but I do not see the smooth transition from issues coming up in other forums to that historic one.

rmazzullo
05-01-2007, 05:09 AM
Bob,

The conventional double jet technique with feedback control to maintain pAg was published by AGFA people in 1964. I'm going to steer clear of Kodak-relate info for now due to some agreement with a few people, but this type of emulsion making setup (commonly called controlled double jet) was in use in research labs of Fujifilm already in 1960s. As I said before, it took a decade or two before this new technology saw practical use with advantage in commercial plant scale. (That is, even with the fancier machine, the engineers couldn't make better emulsion for some time, compared to the old-fashioned method.)

Thanks...

As a follow up, I'd like to do some further reading about this offline. Can you please give me the names / dates / numbers of the papers or patents where this is described by AGFA or Fujifilm?

Bob M.

Ryuji
05-01-2007, 01:13 PM
No, I did no general search for `AgX´. Only at Apug. (Here is another AgX around; he saw some light though…)

Yeah AgX is a good name, but since it's so short it's hard to find a domain and can be expensive :-)



To my information it was in the late twenties that by two other Agfa people (Mathies/Wendt) the predecessor of that stabilizer was found, a sulphur containing heterocycle.[...]But I admit finding these dates is difficult and the results are not necessarily trustworthy as long one did not see the original documents, which I did not.

1-phenyl-5-mercaptotetrazole is a famous sulfur containing heterocycle but I don't think it was from Wolfen. Another family of famous thiol, 2-mercaptobenzimidazole (2-MBI) and 2-MBI with substitution on the benzene ring are very commonly used, both in emulsion and developers, and this is from Wolfen. I thought TAI was late 20s but I was writing from memory, but it was actually the date of the previous generation compounds. I just searched for the date of TAI but date varies from 1935 or 1937. Birr has published a whole book but doesn't say the date of this work! Since this is not the only one he worked on but it just happened to be the famous compound, it may be hard to give a single date. Anyhow, it's mid 30s.

Glafkides say:

The most remarkable of all the photographic emulsion stabilizers are the
aza-indolizines discovered in 1935 by Birr.(32) They were kept secret for many
years, and enable gold sensitizers to be used which, as we know, produce
considerable storage fog.

Duffin (the author of an old emulsion technology book) says 1935.

The website of Organica (ORWO) says:


1936 The "Agfacolor-Neu" is presented to the
world. It is the first multi-layered colour film with
inserted couplers and it wins the Grand Prize of the
Paris World Exposition.
The Sodium salt of the Benzenesulfinic acid
(00540, S-Salt) is used in the manufacture of
emulsions as an antifogging agent since the middle
of the 30 ́s. Later on, other film manufacturers
will use the corresponding salt of the
4-Toluenesulfinic acid (12060).
Trough his search for stabilisers, which do not
have any negative influence on the sensitivity
while using Mercapto compounds, Birr comes
across Triazaindolizines, which Bülow had already
synthesised in 1907. The condensation product of
Ethylacetoacetate and 3-Amino-1,2,4-triazole will
soon be considered to be the perfect stabiliser (12210, TM-2, Sta-Salt). Within
two years it is used in all types of film and replaces the Mebi acid in the
"Agfacolor-Neu" material. Thus, it permits the full benefit of the Koslowsky
effect. This unique combination of Gold complex and Sta-Salt, which has been
kept secret until the BIOS- and FIAT- reports were published, has been applied
world-wide since 1945 in all Silver halide materials.
Until 1945, China-, Oxa-, Selena- and Thiacarbocyanines in form of their
Iodides, Bromides, Chlorates and Ethylsulfates are used as spectral
sensitisers in all black-and-white and colour materials (12680).


All this is getting very special and I guess annoying to some people and I sometimes think it would be better to have a special historic forum, but I do not see the smooth transition from issues coming up in other forums to that historic one.

I always think that forum is a better place for issues of current nature, that is, things that aren't fixed. Historical matters, among other things, are probably better served in the form of wiki or other forms where information is consolidated. Historical matters, of course, are more academic and meticulous checking with references and cross checking with multiple sources becomes more important, but doing this for every single thing in forums is tedious. I can make an AgX wiki site, or just join wikipedia, there are a couple of good options here.

Ryuji
05-01-2007, 01:45 PM
As a follow up, I'd like to do some further reading about this offline. Can you please give me the names / dates / numbers of the papers or patents where this is described by AGFA or Fujifilm?


The Fujifilm info is from a short memoir (published) of an emulsion scientist who is now a professor. It is written in Japanese. I don't want to trouble him since he is still active in publishing his work at Fujifilm and he has also been very kind and helpful. If you read Japanese, let me know off list.

The AGFA report was by F. Claes and R. Berendsen (1965), published in Photogr. Korresp., 101, 37. Claes published a lot around that time, many in English or American journals. He worked at Mortsel lab with Libeer, Borginon, Vanassche, et al., and you can search their relevant work. Basically, controlled double jet method allowed to make a bunch of different kinds of crystals but appearing rather in isolation, due to a specific condition of crystal nucleation and growth. The technique also helped to make crystal size very uniform, called monodisperse emulsion. So monodisperse emulsion of a single crystal shape is a very good research model to investigate the photographic sensitivity. Also, various sensitization techniques were re-investigated on each crystal type in detail at that time. Many of their publications are around these issues. If you just want to get a detailed review of this topic, a very thorough review was written as a book chapter by Jong Wey of Kodak Rochester lab in 1981. The book title is Preparation and Properties of Solid State Materials, VOLUME 6, edited by Wilcox. It describes several theoretical models that were later used in model-based automatic control of plant equipment. He left many issues open-ended because the real answers weren't known then, but many new work, notably works related to tabular grain technology, built on the state of knowledge Wey summarized.

Since you are interested in automatic control, I mention Konica. One of the internal bulletin (public knowledge) described their emulsion process control using both feedback and model-based feed-forward control. The bulletin is written in Japanese, and the report was published in 1990 by Saitoh and Shimoji of Production Engineering Center of Photographic Products Manufacturing Division in Hino, Tokyo.

AgX
05-01-2007, 02:08 PM
Ryuji,

I got my informations on this very topic mainly from publications by former Agfa/ORWO researchers and even they can be a bit contradictory concerning dates. For that non-speed-retarding stabilizer a patent (secret patent) has been applied for at 3 july 1937. (I’m quoting the date.)

But, to my mind, it is less important just to know a very date, but rather in which context a certain development is to be put.
How did people achieve certain ideas? Why was decided in favour of a certain research project? What was the market’s, the competitors’ response? How was the life of those involved touched? And, not at least, I think an invention can even have an inner beauty.

rmazzullo
05-01-2007, 02:22 PM
Thanks,

I have a friend here in NYC who is a chemistry professor and is fluent in Japanese. Can you send me a copy of the paper from Fujifilm, or tell me if it is online?

Also, I cannot find any reference to feedback control in Agfa's patents in the 1970 era or before. Do you know of patent numbers that would have discussed this technique? Even if there is no implementation of a particular technique, most companies would file a patent to protect the idea in the event it is used in the future.

Thanks,

Bob M.

Ryuji
05-01-2007, 02:38 PM
But, to my mind, it is less important just to know a very date, but rather in which context a certain development is to be put.
How did people achieve certain ideas? Why was decided in favour of a certain research project? What was the market’s, the competitors’ response? How was the life of those involved touched? And, not at least, I think an invention can even have an inner beauty.

Totally agreed. I am more interested in how a discovery or technology lead to later work, and also how photographic technology influenced photography. Electronic flash, small formats, pan films, etc. are easily recognized and discussed in many literatures but when you get one step closer things are very rarely discussed.

1930s as a whole was a very exciting time in photographic technology. Works at Wolfen were singular and isolated and the shock of the rest of the world discovering them was pretty obvious. Whether 1935 or 1937 I don't care much.

Ryuji
05-01-2007, 02:54 PM
The Japanese stuff is not online. The article is in the Journal of Society of Photographic Science and Engineering of Japan. You have to email (please- not pm) me since I am not going to put any more info on this here.



Also, I cannot find any reference to feedback control in Agfa's patents in the 1970 era or before.


As I described before, the technology came out of a research/science group from Mortsel and I would not be surprised if they didn't get a patent at that time.



Even if there is no implementation of a particular technique, most companies would file a patent to protect the idea in the event it is used in the future.


Agreed, but at that time the US Patent was 17 years from the date of patent issue (now it's different) and technological advancement wasn't fast enough so that the 17 years wasn't worth the trouble, unless they feared the technology would be used by others before then. (It's actually more like 20 years because people try to delay the process very much to extend the later end of patent protection.)

In reality, controlled double jet was commonly used by research communities in many corporations and universities in 1960s, so I doubt they pursued patent protection for it. It was actually good though, so that the amount of knowledge scientists learned at that time gave rise to bigger waves of technologies later.

Another thing about patent is that you don't wan't to be too specific, and the details of feedback control wouldn't be described in patents unless the inventor is very confident that other ways cannot be used. This is because the more specific you get, the more specific your right becomes (in claims, which is all that matters when you fight in court). You can describe more in the details section, and it gives you the priority of the knowledge, but won't give you the strong (offensive) rights of patent. At the same time, patent examiners don't want to give patents for something very broad and nonspecific (although they do occasionally, and this is a big pita to everyone but the assignee) so it's very difficult to write a strong patent application for a method for which the inventors do not have very clear pictures of all possible end products that can benefit from the method. Good patents are equipped with a couple of broad claims and many small specific claims. Broad claims can intimidate competitors but these are easy to get nullified in court. Specific claims are harder to get nullified. So many specific claims (dependent claims) are included to protect individual product groups separately. Some of these may get nullified but the rest are still valid and still have the full legal power within the specificity of the claims.