Chloro-Bromide emulsions

Photo Engineer · Mar 13, 2011

Kirk;

Let those interested try this then: http://www.chem.purdue.edu/gchelp/howtosolveit/equilibrium/solubility_products.htm

And PKSP or pKsp = the negative log of the Ksp.

And you are correct with the size causing the stress to the extent of the ratio of the sizes times the pKsp values involved factoring in the excess halide outside of the crystal and etc......... It goes on and on and on, but a mixed Cl/Br is tough to calculate and was the weakest point in our model as the sizes were close but no match and the pKsps were close but no match. So, this is a difficult subject and I hate to go into detail. I could not afford the experiments that would be needed to work one out by trial and error.

PE

Photo Engineer · Mar 13, 2011

Try this reference and see if you like the math there. If you do, I might consider going on.

http://www.d.umn.edu/~psiders/courses/chem4633/labinstructions/AgNH3.pdf

PE

Ray Rogers · Mar 13, 2011

Speaking strictly for myself,
I would be interested in a book that goes into such matters in detail,
with the math worked out and full explanations.

So despite the anticipated difficulty, I think there is a need.

If not a whole book, maybe a few pages?

Photo Engineer · Mar 13, 2011

Ray;

A dilemma exists here though. There are many books on pKSp calculations including some on photography, but there are few on making emulsions with examples and formulas. There you have it. Ok, the book is now pushed back to Christmas 2011 and I will add the math.

Howzzat? Opinions please.

PE

rmazzullo · Mar 13, 2011

Photo Engineer said:
Ray;

A dilemma exists here though. There are many books on pKSp calculations including some on photography, but there are few on making emulsions with examples and formulas. There you have it. Ok, the book is now pushed back to Christmas 2011 and I will add the math.

Howzzat? Opinions please.

PE

I am very interested in seeing the extra material. It would certainly help us to fill in the gaps in our understanding.

Photo Engineer · Mar 13, 2011

Did any of you look at the references I gave? That is essentially what I would have to wrestle with to incorporate into the book.

PE

holmburgers · Mar 13, 2011

PE,

Just include a hyperlink in your book to this thread. Is that possible these days with modern publishers?

Hexavalent · Mar 13, 2011

Photo Engineer said:
Ray;

.....There you have it. Ok, the book is now pushed back to Christmas 2011 and I will add the math.

Howzzat? Opinions please.

PE

If software design, this is called "feature creep", more and more bells get added, and the project never gets finished

Photo Engineer · Mar 13, 2011

Exactly Ian. So, the book may be published about 10 years after I'm gone to the great darkroom in the sky!

Chris, I already published a link here and no one liked it, and there is loads of this in most texts on Photographic Science but they seem to want me to repeat it! So............

PE

holmburgers · Mar 13, 2011

I know, I was just joking.

My final thought is, don't feel like you have to go into great depth about these murky emulsions, but give it a little lip service so that a reader is at least aware of its existence and potential pitfalls.

Ray Rogers · Mar 14, 2011

Photo Engineer said:
Ray;

A dilemma exists here though. There are many books on pKSp calculations including some on photography, but there are few on making emulsions with examples and formulas. There you have it. Ok, the book is now pushed back to Christmas 2011 and I will add the math.

Howzzat? Opinions please.

PE

That is true, but I think the issues mentioned in modling are interesting and relates to real emulsions more closely than a lot of the scientific studies that use ideal or special parameters. Well, thats mostly a guess.

Actually, I was really talking about a separate book.

Ray

Kirk Keyes · Mar 14, 2011

holmburgers said:
PE,

Just include a hyperlink in your book to this thread. Is that possible these days with modern publishers?

Hyperlinks come and go - we need something in the book that will last for years.

I think a few pages with short examples, as shown in the links above, would be good. Afterall, a Ksp calculation with AgCrO4 is nice, but some with AgBr vs. AgCl is much better, and would help those that are initially having difficulty with the concepts make the jump into inderstanding.

You don't need to lay it out so that they grok it, but merely enough for a normal understanding of the subject.

Photo Engineer · Mar 14, 2011

Well, I can't include the entire model even if I had it. The code, as I left it, without the graphical user interface took about 3 feet (1 M) of shelf space printed in 8 point type. I could do some simple examples, but remember that this is HARD-CORE CHEMISTRY with math and logarithms and exponentiation.

Adding an edit.

Actually, we had no precise model for Cl/Br. The reason was that Chloride is a Solvent for AgCl and AgBr, as we know from its use in Microdol and other places in photography. This complex interaction further confounded the conditions when you had a mixed Cl/Br making prediction difficult. I can show single relationships and I can "guess" by weighted averages based on pKsp values, but the overall result is difficult to explain to non-chemists.

PE

JOSarff · Mar 14, 2011

Photo Engineer said:
Did any of you look at the references I gave? That is essentially what I would have to wrestle with to incorporate into the book.

PE

Ron:

I looked. I read. I even understood (some). Now I understand why you do not want to include Br/Cl emulsions in this volume, and I agree with you.

It seems that Br/Cl emulsions are a catch 22 situation. The more research you do and the more you think you understand about them, the less you know about them.

Close?

Joe

Photo Engineer · Mar 14, 2011

Joe;

Just about spot on! Thanks.

PE

Ray Rogers · Mar 15, 2011

Well then, could you say a few words here about modelling?

How has it impacted emulsion engineering,
What products we might know were designed or impacted by it,
and
what did Kodak get out of it?

What could one actually do with the graphical interface?

Photo Engineer · Mar 15, 2011

The graphical interface was the Windows menu bar and pull down items such as load, save, etc..... So that is self explanatory I hope.

The model allowed the emulsion engineer to have a CAD / CAM type program at his disposal to figure out mole % of halides and other addenda, to predict crystal habit and to warn about scaling problems. That is what Kodak gained.

In addition, the program linked to the database of chemical addenda so that an emulsion maker could select ingredients that were optimum for his / her emulsion.

It made emulsion engineering quicker, better and less expensive!

All products since about 1988 used some form of the model.

There, I hope I answered all of the questions Ray.

PE

Ray Rogers · Mar 15, 2011

Pretty much, thanks.

How were results presented?
Say if you added a shot of Rh...
Did it show results in crystal images, a verbal description, or a simulated characteristic curve?

Do you have any samples of what a print out from the program looked like?

wildbillbugman · Mar 16, 2011

Ray Rogers said:
Well then, could you say a few words here about modelling?

Well Ray,
I realy think it's a field for younger, more buffed people than we Emulsion Nerds.
I cannot speak for any one else, but I would look DISCUSTING in a string bikini and heels.
Bill

Hexavalent · Mar 16, 2011

wildbillbugman said:
Well Ray,
I realy think it's a field for younger, more buffed people than we Emulsion Nerds.
I cannot speak for any one else, but I would look DISCUSTING in a string bikini and heels.
Bill

That was the first post I read this morning - my day is now scarred

Ray Rogers · Mar 16, 2011

wildbillbugman said:
I would look DISCUSTING in a string bikini and heels.
Bill

I never thought about that.
I guess you are correct.
Mathematicall Modelling is all about numbers... you know... 36-24-36 !

holmburgers · Mar 16, 2011

Hahaha.....

Photo Engineer · Mar 16, 2011

Ray Rogers said:
Pretty much, thanks.

How were results presented?
Say if you added a shot of Rh...
Did it show results in crystal images, a verbal description, or a simulated characteristic curve?

Do you have any samples of what a print out from the program looked like?

Ray;

The presentation of results were in terms of solutions used, methods of preparation, a spreadsheet of the formula and individual tabbed segments of each individual operation. The printout included a "snapshot" of the emulsion formula in terms of "suitability" for scaling, overall operational suitability and it filled in the blanks of unknowns in any calculations (solving equations as it went). It also presented a graph of what the run-time data should look like so that the maker could compare with the actual process data.

It did not give them data on the amount and time to add any addenda as that was the designers job which varied too much from formula to formula.

It did include any post run time data that the user uploaded with the formula.

Basically, it warned the maker or gave an outright error if they violated some standard "rules" of emulsion making.

PE

Chloro-Bromide emulsions

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