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04-27-2008, 09:01 PM
So does anyone have a good patent to look at for sulfur + gold sensitization?

And another:


2,642,361 - Damschroder & Yutzy (Kodak), Photographic silver halide emulsions sensitized with water-insoluble gold compounds, 1953.

Kirk Keyes
04-27-2008, 11:07 PM
Ryuji's suggested patents:

"For Yutzy's acid coagulaion methods, see 2597915, 2614928, 2614929, 2718662 and compare."
http://www.google.com/patents?id=QsFPAAAAEBAJ&dq=2718662 This last one I think must be the wrong number is it's for plastic injection molding... Ryuji - could you check the number for this one?

"In my experience, the coagulation method disclosed in Roth, US Patent 3118766 is superior. It coagulates more easily, enhances adhesion of the emulsion, and the yield of acylation reaction is more complete within the desirable pH range."

"Another problem, a real practical problem, is that these acylated gelatins do not harden with common organic hardeners AT ALL. If you use these hardeners, you must keep the proportion of the acylated gelatin low, and add a non-acylated gelatin after washing stage. This makes gelatin-to-silver ratio too high. Of course, there is work of Yudelson, US Pat 3017280, and more, but these agents are very nasty to make, and many are nasty to use."

"For conventional emulsion work, I use more convenient polymer coagulation method. See De Pauw US Pat 3884701."

Kirk Keyes
04-27-2008, 11:13 PM
"The laminar structure tabular grain is not very easy to make [...] Indeed, this invention was superseded by Kodak's own people, e.g., US Pat 5518872."

"The main signficance of this patent is its claim 11 and examples 2, 4, 6 and 7. However, use of hexacyano complex dopants are phased out by Eastman Kodak, Fujifilm and Agfa, at least, due to toxicity of waste water. For alternative technologies, see US Pat 6732419 B1."
Ryuji - could you check this number as well.

Photo Engineer
04-28-2008, 09:24 AM

The patent in post 43 is a secondary patent to the original 2 electron sensitization that uses ligands other than cyanide. The original used pentacyano-dye-osmate complexes. Ken Reed, Gerry Klein and Roger Weiss have been doing a lot of work lately I see. I know the 4th inventor by name only. However, the originator was A. Munter (sp?) at Kodak.

The patents on ISO washing are listed in a group in Haist at the end of the chapter on emulsions. There are probably 10 examples that list the evolution of PA washing. Incidentally, one of my patents involves the use of polystyrene sulfonic acid (PSA) in gelatin for preparing salts of cobalt complexes. PSA can be a two edged sword.


Photo Engineer
04-28-2008, 12:55 PM
I was looking at patent #5518872 again and noticed the date. Interesting, as I was working with Ken on his graded iodide emulsion (which I mentioned elsewhere and which is listed above), and I never knew the metal complexes that were being used. This is how compartmentalized the Kodak system is. I had codes obviously, but had no idea at that time what the key to all of the codes were. You needed a key, and the need to know. Later I had the key but was working on other emulsions then. It took me this long to recognize that. Then suddenly, I had one of those AHA moments.

This is a pefect illustration of the Kodak system. It is also why I cannot recreate everything from scratch. It isn't easy fitting these pieces together and that is why I warn about patents constantly. Even with inside information it is sometimes hard to draw connections between patents.