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hrst
09-10-2010, 05:12 PM
Hello,

Can you point out some kind of useful resources (books, patents, websites or anything) that describe the silver halide crystal growth process of modern emulsions? I mean these vAg and pump rate thingies.

I've started designing and building a syringe pump station with emulsion design and pumping control software that works on PC, but I don't know anything about underlying theory on pumping rates, process control and vAg feedback loops yet.

Photo Engineer
09-10-2010, 07:17 PM
A recent book by Ingo Leubner is a very good technical source if you wish. It gives growth rates based on crystal habit for use in this type of work. However, there is no hard and fast rule in some aspects of this work as it is very empirical in some cases.

For the feedback loop, you will need a very good PID algorithm and input the correct constants (which vary) over the range of emulsion types. The flow rates may be constant, a linear increase, a quadratic increase or an exponential increase. In all cases, you will find that salt flow is greater than silver flow to maintain a given vAg due to the increasing ionic strength caused by the buildup of Nitrate ion in the solution.

You will also need to use the salt bridge described here in another thread. Otherwise the measuring electrodes will contaminate the make and offset the values being measured. A rapid response will also be necessary.

PE

dwross
09-10-2010, 09:43 PM
If you are willing and able to plow through the math and chemistry, I can recommend 'Photographic Sensitivity- Theory and Mechanisms', by Tadaaki Tani, Oxford University Press, 1995. Here's a sample page:

dwross
09-10-2010, 10:01 PM
I just checked the availability of the Tani book on Abebooks. There are plenty of copies.

If you aren't yet familiar with www.abebooks.com, you're in for a treat. It has a particularly good keyword search engine. (Set a book budget, though!!)

hrst
09-10-2010, 11:31 PM
Thanks;

I ordered a used copy of Tani's book from Amazon.

Leubner's book was freely available as a PDF copy so I printed it by myself.

Both of these books look very good and are just what I was searching for.

I think I have some night reading now for a while. Thank you very much for both suggestions!