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Photo Engineer
04-09-2007, 04:13 PM
So basicly our semi-automatic-amateur-setup would replace a fairly small number of containers of chemicals only at the maximum concentration with a larger number of auto-syringes? In our case, you'd have two syringes, one with 0.2 molar silver nitrate and one with 2 molar silver nitrate?

Yes, that is correct. The only 'automation' would be a plunger actuator for each and a timer for each with a push button to start the plunger. The syringes would have to have a head of air in it to force the last of the Ag solution out with air.

If you wanted to run anything else with either syringe, then you would have a 2 or 3 syringe system delivering the several solutions at the same rate. This method would not allow for control of vAg though but it would be close enough.

PE

rmazzullo
04-10-2007, 08:26 AM
Thanks PE,for the post describing a basic automated delivery system. This is blockbuster information.

Is it possible to build an emulsion mix, without the silver nitrate or other sensitizing agents, in order to fine tune the emulsion mixing, coating and drying 'sections' of an automated setup? It would seem obvious to test equipment that is built without wasting silver nitrate and other chemicals that are expensive, and light sensitiive.

Are the physical properties (viscosity, 'smoothness', etc) of an emulsion significantly affected by the addition of the light sensitive ingredients? If so, can these effects be compensated for when testing equipment builds?

Thanks,

Bob Mazzullo

PeterB
04-10-2007, 08:33 AM
Here is my description of a fully automated precise delivery system....
....PE

Thanks for that PE. I've decided that the extent of my interest for now will be to try to understand as best I can the process behind one delivery system. I have so little spare time on my hands right now that I type this reply during an act of procastination and semi-awakeness !!!

Anyway if I could sufficiently understand the process to a level that I would be able to put it into an (Engineering) requirements specification, then I would be happy.
So my questions
i) Does this process bear any association with this (http://www.apug.org/forums/attachment.php?attachmentid=7241&d=1174502645) diagram ? I like to work with diagrams as well as words. As an Electrical Engineer, I design and communicate in circuit diagrams and program in LabVIEW (http://www.ni.com/labview/) (a graphical dataflow programming language)

ii)You mention two jars. One with 2 molar silver nitrate , the other with DW. Yet in replying to wirehead you agree with his interpretation that the two jars are really 0.2 molar silver nitrate and 2 molar silver nitrate. Which one is it?

iii)If you intend your process description to have a relationship to this (http://www.apug.org/forums/attachment.php?attachmentid=7241&d=1174502645) diagram then why don't you mention anything about mixing in the Br- ions ? Do you allude to the Br- when you write "Now, multiply this by the need for running salt (in control) or two salts (one in control and one not),"

iv) What do you mean when you say one salt is not (being) controlled ?

regards
Peter

Photo Engineer
04-10-2007, 09:14 AM
Thanks PE,for the post describing a basic automated delivery system. This is blockbuster information.

Is it possible to build an emulsion mix, without the silver nitrate or other sensitizing agents, in order to fine tune the emulsion mixing, coating and drying 'sections' of an automated setup? It would seem obvious to test equipment that is built without wasting silver nitrate and other chemicals that are expensive, and light sensitiive.

Are the physical properties (viscosity, 'smoothness', etc) of an emulsion significantly affected by the addition of the light sensitive ingredients? If so, can these effects be compensated for when testing equipment builds?

Thanks,

Bob Mazzullo

Bob;

A part of my budget every year included water runs of 'emulsions' that were intended to test the timing of events when scaled up or down and testing new formulas for proper timing, so yes the equipment must be tested.

The emulsion itself has a different viscosity than each of the ingredients alone. This is primarily due to the binding of silver halide to the gelatin, a process called peptization. My students practice coating plain gelatin in the light, and when they being coating the same level of gelatin / emulsion, they are astounded at the drastic change in viscosity and coatability.

PE

Photo Engineer
04-10-2007, 09:24 AM
i) Does this process bear any association with this (http://www.apug.org/forums/attachment.php?attachmentid=7241&d=1174502645) diagram ? I like to work with diagrams as well as words. As an Electrical Engineer, I design and communicate in circuit diagrams and program in LabVIEW (http://www.ni.com/labview/) (a graphical dataflow programming language)

ii)You mention two jars. One with 2 molar silver nitrate , the other with DW. Yet in replying to wirehead you agree with his interpretation that the two jars are really 0.2 molar silver nitrate and 2 molar silver nitrate. Which one is it?

iii)If you intend your process description to have a relationship to this (http://www.apug.org/forums/attachment.php?attachmentid=7241&d=1174502645) diagram then why don't you mention anything about mixing in the Br- ions ? Do you allude to the Br- when you write "Now, multiply this by the need for running salt (in control) or two salts (one in control and one not),"

iv) What do you mean when you say one salt is not (being) controlled ?



Peter;

Answers as follows:

1. This diagram is a simplfied schematic of what I describe in more detail with the Ag/DW example.

2. Wirehead was asking how to do it with syringes injecting solution into the reactor. In his case, dilution in-line cannot be done, so you need 2 syringes, one for each concentration of silver. The two jars, Ag and DW make up one delivery system. Another might be X and DW. Again, two jars but a second full delivery system. None of this is shown in the simplified schematic.

3. That would involve 2 delivery systems, and I did not want to go beyond one in the word description. Actually a real system has many many jars coupled in pairs with many many delivery systems under this type of overall reaction method.

4. Silver runs at 0.2 M or 2.0 M. Salt would be at 0.2 M or 2.0 M to match the silver, but the salt flow would be at a rate to achieve a constant vAg via feedback control. You can see that in the diagram referenced here. However, if the salt contains both KI and NaBr, the chatter induced by the feedback control would cause chatter in KI deposition and therefore it would cause banding in the emulsion of KI rich sites which is not good. For this reason, KI is often run at a contstant rate from a third delivery system made up of a pair of KI and DW jars which feed into the reactor so as to avoid any chatter in the NaBr line flow.

Now do you see how complex it can be???

So, to design an automated formula that is both modern and yet not automated to the extent used at EK will take a bit of my design skills before I can say - "this will work".

Posting things here and getting feedback is a way of my understanding what can be done without spending a fortune on equipment.

PE

rmazzullo
04-10-2007, 09:29 AM
Bob;

The emulsion itself has a different viscosity than each of the ingredients alone. This is primarily due to the binding of silver halide to the gelatin, a process called peptization. My students practice coating plain gelatin in the light, and when they being coating the same level of gelatin / emulsion, they are astounded at the drastic change in viscosity and coatability.

PE

PE,

Is it possible to use another, (hopefully cheap) compound to bind to the gelatin, to get close to the viscosity / coatabilty of the finished emulsion? It might take some searching, but it would bring tuning the equipment closer to the ideal. Could it be as simple as adding a non light sensitive salt to the gelatin in place of the silver nitrate, for testing?

Thanks,

Bob

Photo Engineer
04-10-2007, 09:38 AM
Yes, provided you had the means to test viscosity. I have found that this is really not needed and was not done at Kodak. The pumped or running materials were all almost like water. It was only the gelatin solutions that differed.

PE

rmazzullo
04-13-2007, 06:35 PM
Hello all,

This is a link to an article that gives some basics on electrodes much like what might be used here:

http://www.currentseparations.com/issues/14-2/cs14-2d.pdf

Thanks,

Bob M.

rmazzullo
04-13-2007, 07:04 PM
one more...

some more background information on electrodes as used in electrochemistry; interesting circuit diagram.

http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ64941.pdf

Thanks,

Bob M.

rmazzullo
04-13-2007, 08:24 PM
sorry all,

One last document describing the basics of pH.

http://www.emersonprocess.com/raihome/documents/Liq_Handbook_44-6033_Theory_And_Practice_Of_pH_Measurement_199909. pdf

Bob M.

rmazzullo
04-14-2007, 06:54 PM
Hello all,

In keeping with the 'low cost' aspect of using external controls for emulsion making, I have a suggestion for a possible mixing system / feedback loop based on one of the earlier posts regarding using lead screw actuated syringes.

Say you have 'x' syringes containing separate ingredients for an emulsion mix. Each syringe is actuated by a small variable speed motor controlled lead screw. Alongside each leadscrew, is another shaft that has "limit" switches mounted on it but can be moved along the extra shaft and secured as needed.

The action of the lead screw on one syringe moves an actuator (metal projection, etc) that passes and trips the limit switch (or switches), starting or stopping other syringes / steps. Each of those motor driven syringes have their own limit switches set at respective points to start, stop or delay other syringes, valves, etc.

If you have electrodes in the emulsion, the feedback signal could speed up or slow down one of the motor driven syringes to keep the vAg at a desired level.

The wind up is that you may not need a PC to control emulsion mixing on a small scale. An arrangement of switches, small relays, and motors, with a feedback signal supplied by the electrode(s) used to alter the rate of delivery of important ingredients.

There are shortcomings to this approach (need to hold voltage to a motor, and resultant speed, constant, hardware, etc ,etc) but, this is only an idea.

Thanks,

Bob M.

Photo Engineer
04-14-2007, 07:03 PM
Bob;

It depends on what you want to make. I can make an Azo/Lupex like emulsion and a Brovira/Kodabromide like emusion with no control whatsoever. Early emulsions were single run and needed no control or were double run with no control.

So, the 'look' of the 20s - 50s could be done, as I have repeatedly said here, with no control. I don't want to lose sight of that fact.

PE

rmazzullo
04-18-2007, 10:18 AM
Hello PE,

For the sake of discussion, assume you have a working, precise and repeatable delivery and feedback 'system'. Is it possible to tailor the emulsion using the vAg value as an 'indicator' (one vAg value indicates an emulsion with 'x' properties, while another vAg value indicates an emulsion with different properties)? This is also assuming you are working within an acceptable "range" of vAg values.

This may have been covered before. If so, can someone point me in the direction of the right thread?

Thanks,

Bob

Photo Engineer
04-18-2007, 12:30 PM
Yes, I thought I mentioned that.

The range spans from cubic to octahedral to T-grain to K-grain depending on vAg. I believe the actual values are posted here in this forum.

But, you can also do this without control by picking the salt level. I gave some salt / pX/ pAg values elsewhere as well, maybe the same thread. At worst, without control, you get a dominant crystal and then a mixture of others which depends on what pAg value you drift towards and by how much.

PE

rmazzullo
04-18-2007, 01:13 PM
Hello PE,

Yes, you did.

It was all explained previously. I lost track of where it was.

Thank you, regardless.

Bob

Kirk Keyes
08-01-2008, 03:13 PM
From what I am reading on this forum, it seems like the process of emulsion making on a small scale would benefit tremendously from using small stepper motors, servos, solenoids, etc (machine control) to keep certain steps in this process more exact and repeatable.

This thread is fun. I thought I would bump it. It's been a year - Anyone have any other thoughts on the subject.

Photo Engineer
08-01-2008, 03:44 PM
You know I do Kirk! :D

I am about to embark on that for the second part of the DVD.

I have peristaltic, diaphragm and centrifugal pumps for this purpose.

TaDa!

PE

Kirk Keyes
08-01-2008, 05:08 PM
Well, I knew you did. I meant the others involved or new to this type of endeavour.

Kirk Keyes
08-01-2008, 05:09 PM
And how did I miss this entire thread until now! I guess I was getting ready for your class last year...

ben-s
08-01-2008, 06:49 PM
I've kind of gone off the boil on this side of things at the moment.
The cost of setting up such a system without having ready access to the knowledge needed to run it without generating a lot of expensive gloopy mess is too high for me at the moment.
While automated systems can have huge benefits, to quote an old colleague of mine, "Automated machines can generate scrap at an astonishing rate"

However, if I can help anyone with the automation side of things, please shout and I'll do what I can.