Automated Emulsion Making - more modern formulas

[Photo Engineer]

I have been following the thread on using stepper motors for emulsion making and have been rather surprised at the number of people who want to get into it.

I don't have the financial resources to do this type of work, but I would be willing to whip up some sort of 'manual' or 'tutorial' along these lines. I would also be willing to set up some sort of advanced workshop if anyone is interested and if we can find the equipment and lab to do it in.

I'm trying right now to locate a simple epoxy syringe with two plungers and two tubes to try a controlled delivery of silver and salt, as you have gotten my interest up on this. I could imagine it being done by hand even. I hesitate using one that has already had epoxide in it, as such a 'used' syringe may contaminate the silver or salt.

I've been sitting here running double run, pseudo control emulsion formulas through my head all afternoon thinking of ways to simplify this sort of make and how to automate it.

I've also been contemplating a large scale (1 KG) run of the Azo type emulsion using a heavy duty mixer that I have here. I've just never given a thought to making one that big and you have gotten me curious. It took me about 5 100 gram runs to get one that worked when I first started. Now it scales just fine, but I'm curious. I have always stopped at 600 G.

So, is anyone interested? If so, I may put some ideas down on paper, otherwise with just 2 or 3 interested, it will have to wait until I get a better film emulsion with my current formulas.

Just for starters, I'll throw out some intriguing ideas....

Make a small run, say 100 grams of a concentrated emulsion.

Dilute it with lots of gelatin and salt and then run in a second batch of silver in a second run over top of it for a total of 500 Kg.

This way you make your 'seed' emulsion, and then grow on top of it with totally different conditions. BTW, this is nothing new, but does take a bit more control and darkroom manipulation. It also moves us from the 20s-40s into the 50s-60s. I've been staying away from this type, as I was trying to duplicate the early century emulsions, but interest seems high enough in more modern makes so I thought I would put the idea forward.

Bigger batches and more modern (50s-60s) formulas are possible, and with simple control may be very interesting.

PE

 

[rmazzullo]

Count me in!!!

PE,

I am definitely interested. I have a machinery dealer friend who sometimes comes across pharmaceutical / food grade stainless steel machinery and equipment. He buys all or parts of companies that use this equipment and resells it, pieces at a time. I will ask him to keep an eye out for any small to mid size items that would be applicable here.

I think 60cc syringes (no needles) should be available over the counter at a surgical supply store, maybe even online, but I'll have to check on that. I don't know offhand of a source of unused dual epoxy dispensers, but I will look around.

I came across an interesting web site that describes syringe pumps that are closed loop, and do not necessarily require a PC for control. I don't know if the device is appplicable, but cost notwithstanding, it gives you ideas. Take a look here: http://www.syringepump.com/NE-16001800.htm

If a 1 kg run of the Azo emulsion was produced, you could possibly adapt Jim Browning's coater almost as it is, to produce large sheets for cutting to size afterwards.

The idea of using a seed emulsion is very interesting.

I would very much like to see your ideas, and I hope others will respond.

Thanks,

Bob Mazzullo

 

[Photo Engineer]

Bob;

I have a 16x20 blade and an 11x14 blade. The 11x14 produces fine coatings but I have trouble handling the 16x20 manually. In any event, at 12 ml / sq ft, even a 600 gram run makes a lot of 8x10s. I regularly produce 17 - 20 8x10 sheets from 200 g of emulsion.

I've found many sources for peristaltic pumps and for syringes. Some are usable and some are not. It would be a rather lengthy discussion to explain all of the details.

Just to mention one... Line fill or line residue is one problem. You have to totally flush the line, but you cannot dilute the solution. There are several solutions, but that is one. The second is the cost.

I can handle it manually, but doing it automatically is a problem.

Thanks for the answer.

PE

 

[ben-s]

I'm interested, as you may have guessed from the other thread
I've had a look at a couple of scientific suppliers here in the UK, but I can't see double syringes.
The best option may be 2 syringes clamped together.
Either that or talk nicely to one of the epoxy manufacturers!

 

[Steve Smith]

At work, we use this sort of thing for dispensing UV cure encapsulant:
http://www.efd-inc.com/dispensers.html

It is an air propelled dispenser.

We also use the twin syringes for epoxy mixing but these are suplied loaded with epoxy. I will investigate to see if empty double plunger syringes are available.

Steve.

 

[steven_e007]

I'm interested, too

Although I'm not yet ready. I have a lot of catching up to do. I really do need to start making those simple emulsion... walk before you can run and all that. I'm off to search the archives for some simple formulas to maybe have a go next week. If anyone can save me a bit of searching by pointing me in the right direction I'd be very grateful. I'm really after something to coat a glassplate with for negatives. Thanks.

I notice that I am not the only one on the wrong side of the pond for attending a workshop, but a manual or on-line tutorial would be great.

As for stepper motor control of syringes. I have a stepper controlled lead screw assembly sitting in my garage doing nothing and I work in the medical profession so I am surounded by disposable syringes

These are really easy to get from chemists shops (drug stores) anyway. Just ask. They will frown and demand to know what you want them for. Tell them that you don't want any needles and that it is for measuring photographic chemicals and they relax (when they reaslise you don't want to inject yourself with drugs ) and sometimes give them away for free. I've often aquired one in this way to measure Rodinal.

Surely a double syringe is just two single syringes stuck together?

Although I don't think I'm ready for making automated emulsions, yet, I might see if I can set up a stepper motor to control a syringe full of water - just to see how it works.

Steve

 

[rwyoung]

I'm trying right now to locate a simple epoxy syringe with two plungers and two tubes to try a controlled delivery of silver and salt, as you have gotten my interest up on this. I could imagine it being done by hand even. I hesitate using one that has already had epoxide in it, as such a 'used' syringe may contaminate the silver or salt.
PE

I obtained a double syringe plus a pistol grip for appying measured amounts for a work project several years ago. My boss had a good friend who was a dentist and the dentist "loaned" us the pistol grip part and a few new syringes. They were orginally intended for mold making.

I am no longer in contact with this person nor do I have the equipment but it might be worth asking your dentist if they have ever seen such a thing or can show you one of their industry insider magazines or catalogs.

On a related note, there are small, table-top pneumatic systems intended for dispensing "liquids". Kahnetics comes to mind. However my only experience with these was to apply dots of solder paste, not a continuous flow.

 

[Photo Engineer]

Ok, I may as well give an idea of at least two of the problems with double jet syringe addition.

If the plungers are not linked together, then they are no better than having a pair of separate syringes, as they can 'chatter' independantly.

And, if they are machine driven, how do you empty them completely? There will always be a small amount of solution left in them. It is possible to eliminate the residue by either one of 2 methods both of which become more difficult with automation. (BTDT)

You can put a head of air over the solution equal to the volume of the delivery line (difficult to do as you don't want air in the emulsion itself) or you can suck emulsion backwards into the syringe with reverse action on the plunger (difficult if the plungers are automated or separate). (also BTDT) This head of air often will not work with geared or peristaltic pumps as they stop when dry, so other methods have to be developed.

At Kodak, it was simple for me to specify syringe use for a solution as I just wrote Ag/s in the formula or X/s and I never had a worry because anything I wanted was at hand. That little /s changed the delivery system for me without otherwise lifting a finger except to type it in on the keyboard. Now I'm limited by budget, space and time and I assume you are too.

I hope we can mutually solve the problem. Now you are showing me that there is interest so I'm getting myself focused on this a bit (as opposed to doing things for my regular workshop)

Steven;

I've posted 2 formulas on APUG already and there is a Kodak formula that was posted here by someone else.

PE

 

[rmazzullo]

possible alternative to ingredient delivery

This would have to be wrestled with a bit, but would something that would deliver ingredients into the mixing vessel much like a fuel injector *but smaller* (metered jet stream, quick opening and closing) be more like what is needed? Yes, it would necessitate a source of pressure, and some sort of control, but that would tie in to the automation aspect.

Or am I totally clueless?

This just occurred to me, and could be the result of too much caffeine, so your patience is requested.

Thanks,

Bob Mazzullo

 

[Photo Engineer]

Bob;

That would work. Of course, as you say, it would have to be wrestled with a bit.

PE

 

[rmazzullo]

PE,

Can you discuss what would happen to an emulsion if it was mixed at different speeds? In other words, what would happen if the mixer was run at, say, 200 rpm for 'x' duration for a particular emulsion run, and say, 2000 rpm for the same duration for different run, assuming all other factors are equal (for the sake of discussion)? What about adding some sort of vibratory action to the entire mixing vessel during the mixing operation? Would there be a difference in the grain size? Also, would the delivery rate and / or intensity of the ingredients into the gelatin differ accordingly?

I know this is getting ahead of the discussion at hand, but I was wondering what would happen....

Thanks,

Bob Mazzullo

 

[Photo Engineer]

Bob;

I honestly don't know the answer to that one. I can say that mixer speed at EK was varied as a function of volume and that is all I can discuss. We had a very complex mixer model that was used which was a function of volume and dv/dt or change in volume as a function of time.

PE

 

[PeterB]

show me the diagram

Hi PE,
I recently saw a diagram that I think you drew, it details the automated mixing of an emulsion - but I can't find it again. Do you know where it is?

According to the 'boundaries' I laid out (there was a url link here which no longer exists), does that diagram I refer to above push the limits of what you are allowed to disclose?

regards
Peter

 

[Photo Engineer]

Peter;

Sorry, I don't see a post of yours on that referenced page. The diagram is in this forum in another thread. Just look for the paperclip icon to see threads with attachments and you can probably find it.

That diagram does approach the limits of what I feel comfortable with, but I'm working on a post with more information using only words which may help explain things better.

PE

 

[PeterB]

Hi PE,

I (there was a url link here which no longer exists), thanks. I'm not sure why you can't see (there was a url link here which no longer exists) to a post of mine. Anyway not to worry. I'm now going to read through (there was a url link here which no longer exists) descriptive post.

regards
Peter

 

[rmazzullo]

vAg electrode sources?

Hello all,

Does anyone know of a commercial source (or sources) of the type of electrodes needed to properly measure vAg?

On the outside chance these electrodes can be made in the home workshop, is any information available on how to build them?

Thanks,

Bob Mazzullo

 

[Photo Engineer]

Bob;

There appear to be none, but I'm working on this with a friend. Stay tuned.

PE

 

[rmazzullo]

Hello PE,

I found this document on the Kodak web site. It is part of the "Processing KODAK Motion Picture Films" manual, module 3, titled 'Analytical Procedures'.

If the necessary plating solutions were changed appropriately, could the same plating procedure be used to create an electrode that we can use?

The document is here:

http://www.kodak.com/US/plugins/acrobat/en/motion/support/processing/h243/900.pdf

Other than that, the same manual has a section on the use of 'volumetric glassware and weighing equipment' and seems like good basic information.

The link for the whole "Analytic Procedures" module is here:

http://www.kodak.com/US/plugins/acrobat/en/motion/support/processing/h243/h2403.pdf

Thanks,

Bob

 

[Photo Engineer]

Bob;

Ummmm, no, it will not work. "What is the other electrode?" is my first question. My first observation is that the scale for this electrode is way off from what is desired for emulsion making as seen in the second reference. That scale goes from about -500 mv up to about -200, whereas the scale we work with runs from about -250 to +250 mv. The only useful fact is the statement that the electrode should be silver and should be plated with the dominant ion you wish to measure.

No, I'm afraid it is different than what is described. Similar but different. As I said, I'm working on it with an associate.

PE

 

[rmazzullo]

Damn and blast. I guess if it was that easy, it would have been done already.

Bob

 

[rmazzullo]

delivery system concept

Hello all,

I have an idea for a solution pump that needs some input from the list members who are more familiar with the programming or the mechanics that might be required. This is only addressing a portion of a possible delivery and feedback system. Measuring vAg and mixing is not discussed in this message.

If you tie a stepper motor to a small peristaltic pump unit, shouldn't it be possible to measure out exactly what you need to add to the emulsion based on the amount of steps the motor has to complete? Also, if you tie an optical encoder (a cheap one is a few bucks, or you can take them from an old computer mouse) to the output of the pump shaft, couldn't this be used as a type of "flow meter" to get feedback into the motor control circuit?

The idea is that if the fluid amount in a given length of a particular diameter of tubing is known, the peristaltic pump can be designed to move that same unit of fluid between cam lobes (or 2 one-half cam lobes [not two-and-a-half] if you want to reduce pulsations in the line) over 'x' amount of time.

A peristaltic pump is a loop of flexible plastic tubing, held in a semi circular housing, and an rotor with 'x' number of sides [4,5,6 etc] with rounded corners rotates within the same housing as the tube, squeezing the tubing as the rounded corners of the rotor travel past it, pushing fluid along the length of the tubing. These are physically simple devices, and you can make the pump housing out of plastic using a forstner bit, and use small blocks of nylon, teflon, etc, for the rotor. The caveat here is that you must make the pump rotor as geometrically correct as you can (square, pentagon, hexagon, etc must be precise, not lopsided, and round the corners slightly). The rotor has to travel within the housing, but far enough away from the housing edge to allow for the tubing to be mounted along the edge, and squeezed as the rotor travels past. Too close to the tubing and the rotor will bind and stop.

What I am trying to figure out is if a small piece of slightly larger diameter tubing inserted somewhere in the middle of the original diameter tubing, after the pump output, would act like an 'expansion chamber' smoothing pulsations in the line. Or, would building a pump cam with say, 8 lobes instead of 4, would smooth out the pulsations to a manageable level.

Again, the thinking here is that accurate delivery of ingredients would require feedback of the actual amount of solution delivered to the mixing vessel (if you add the recycling feature mentioned in an earlier post by Photo Engineer, the motor will be running at the right speed when the valve is switched to deliver the solution to the mixing vessel at the right rate and duration).

I know this is adding up to more complexity, but while it is more involved, this may not be expensive to build at all. Another forum member mentioned using free CNC software to control the motors. I haven't looked yet, but this might fit the bill, if we can control more than 3 axis. Where the problem lies is in accurately measuring vAg, and how to integrate that feedback signal to adjust solution flow as desired.

Your comments are appreciated.

Thanks,

Bob Mazzullo

 

[Photo Engineer]

Bob;

1. The solution motion is a series of pulses that have to be turned into a steady flow at the delivery end of the tube.

2. The tube changes diameter (relaxation) during use and changes volume with every use and so must be calibrated.

3. etc... BTDT. It works. It just has several years worth of problems to work through and program. We had a whole team of engineers and $M or more.

PE

 

[rmazzullo]

PE,

Do you mean that over time, the tubing wall itself "weakens" and the diameter increases? Was this effect seen only at the portion of the tubing directly impacted by the pump rotor?

Thanks,

Bob M.

 

[Photo Engineer]

Bob;

Yes indeedy do. The pump rotor gradually weakens all plastic tubing and the diameter changes gradually by a fair amount.

In addition, any replacement tubing is different in diameter when averaged over even one foot of length as it is not made to very exacting tolerances. Therefore, before each run, the tubing must be carefully calibrated for delivery and of course a correction must be put in for the calibration process itself which further weakens the tubing. You get this as a dv/dr (change in volume per run) in which time of run is part of that polynomial. That term is dv/dt so you might say it is one or two integrals depending on viewpoint. So, how is your calculus?

And then of course, the fluctuations change (pulsations) due to the rotors depending on speed and tubing wall thickness. This also has to be solved. We did this quite elegantly at EK IMHO. I had nothing to do with it. It is unpublished work by that friend who did the scuba diving.

PE

 

[rmazzullo]

PE,

My calculus is extraordinarily rusty. Something else I am going to have to brush up on....

Thank you for your help,

Bob M.