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AgX
01-05-2009, 10:23 AM
Bob,

Those photos look like stills from some `weird professor´ movie. So, in case that emulsion thing won't work, there still is Hollywood...

I like those filaments in the bulb.

Kirk Keyes
01-05-2009, 02:14 PM
I like those filaments in the bulb.

Looks like the filaments are a heat-wire vacuum guage...

Bob - there's no shame in failure. How better for us all to learn. And if I get around to working on silver electrode, I'd be happy to share my findings. Good or not so good.

rmazzullo
01-05-2009, 02:40 PM
Bob,

Those photos look like stills from some `weird professor´ movie. So, in case that emulsion thing won't work, there still is Hollywood...

I like those filaments in the bulb.


OK...I have to nip this in the bud before it gets out of hand.

Sorry folks, those photos are indeed movie stills...I hope some of you picked up on the wink (;)) the first time around. I couldn't resist the urge. Judging from the spike in hits to this thread, I should have done this on April 1st.

---------------

Kirk,

I have to study and understand more about electrochemistry before I can really contribute to these discussions.

Bob M.

Kirk Keyes
01-05-2009, 02:58 PM
Bob - OK, feel free to ask. But I have to admit electrochemistry is not one of my strong points! But I do enjoy instrument design.

wildbillbugman
01-05-2009, 10:32 PM
Bob and Kirk,
Those stills actualy remind me of (my memory of) the Chem Lab for my freshman Q.A. course in 1966! Things were alot different back then!
Bill

Kirk Keyes
01-06-2009, 03:46 PM
PE - do you have some example patents to recommend looking at for this methodology?

Photo Engineer
01-06-2009, 04:06 PM
None whatsoever. Sorry.

This, the Kodak kettle design and other arcana are deep dark manufacturing secrets.

PE

Kirk Keyes
01-07-2009, 12:26 AM
Could you look at US 3505068 - it looks similar. It uses a "buried iodide emulsion"

Photo Engineer
01-07-2009, 08:39 AM
The 1970 reference in that patent, and the names of the inventors tell me immediately that it is not a "modern" emulsion, but rather was just at the turning point of many of these techniques. For some reason I could not view the whole patent. I'll check later at the US patent office site.

PE

Kirk Keyes
01-07-2009, 10:27 AM
There's another more recent one I think that uses "core shell" techniques. I'll see if I can find it.

Photo Engineer
01-07-2009, 12:14 PM
I have posted the patent number of several of these. I believe that one author is Ken Reed. Not sure, but he is the author of one patent # I posted here.

PE

Kirk Keyes
01-08-2009, 03:37 PM
OK - here's one from Ciba-Geigy in the 70s that looks like it follows much of this process: 4184877.

Photo Engineer
01-08-2009, 05:49 PM
Kirk;

In patent 4184877, the difference is that Ammonium Halides are used, and the Iodide is not ramped down. And so, the result is not a graded core shell, but rather an abrupt core shell. At least I assume that, as the Bromide was added after the Ammonia digest was completed. And, contrary to my example, the core is a mixed Br/I not pure I. This seems to be what they are saying.

I didn't look at the figures, but I assume they are rather thick grains. IDK. It is old. More modern T-grains are thinner I would think and not use ISO washing as is noted in the patent. The emulsion is not very monodisperse at 20% variance, but I'm not sure how they used it and again, I didn't look at the figures.

PE