agitation by vibration ideas and suggestions

[Jay DeFehr]

A question was asked about agitation with 4-up film holders in another thread:

http://www.largeformatphotography.info/forum/showthread.php?t=65723

and generated some very interesting discussion and suggestions I'd like to see continue here. My apologies to Richard again, for hijacking his thread.

mmmmdoughnuts made some very interesting points about acoustics, and Mike, Dan, Gem and Rick had some very interesting ideas, as well.

Doughnuts,

I was thinking in terms of membranes spaced very closely, and the fluid in the boundary layer against the film, since this is where the action is, but I'm willing to consider the possibility the whole idea is not feasible, too, and I see your point about moving fluids. What about using the film itself as a sort of diaphragm pump? Even a 4x5 sheet of film is a large diaphragm.

[Jay DeFehr]

http://upload.wikimedia.org/wikipedia/commons/c/c5/Membraanpomp.svg

Visual aid! Imagine the green membrane is a sheet of film. I'm imagining the action on a much smaller scale, and the membranes being flexed by the kind of acoustic pressure doughnuts mentioned.

[Gem Singer]

Jay,

As an example, with nitrogen blast agitation, the level of the developing fluid is moved up and down, vertically.

You need to derive a system for moving the developing solution in a lateral, as well as a vertical direction.

Paterson makes a unit that swirls the fluid in a circular(orbital) pattern, but I think it only handles a single sheet at a time.

How about a developing system that circulates the developer in the tank while the film stays still?

[Jay DeFehr]

Gem, that's exactly what I'm thinking! I'm still not clear about the best way to move the fluid, but every post gives me a new idea. I like the idea of making the developing chamber a pump chamber. It seems to me a series of tiny check valves could distribute the fluid to keep the flow random, even in a very small chamber.

[DanK]

I like the ideas...and of course, the impossible just takes longer....but...

I'm not quite sold on the fluid movement theory - thinking it is a pretty difficult variable to control...especially with film emulsion...

Any slight deviation can and will change the flow pattern...

I have a little experience with flow patterns and predictability of fluid movement in much larger scale, as a drilling fluid engineer the last few years - and I can say a good majority is fuzzy math...

Love to see where this thread goes (actually considering a little testing myself)

Thanks,
Dan

[Jay DeFehr]

Dan,

I'm writing from my desk in Prudhoe Bay, Alaska. I have a lot of respect for drillers.

I'm imagining a box, one side of which acts as the membrane in a membrane pump. On the inside of the box walls would be ports with check valves. As the membrane moved, changing the size of the chamber, the fluid in the chamber would circulate as directed by the placement of the check valves. Since the fluid isn't being pumped anywhere, just circulated, there would be positive and negative pressure strokes circulating the fluid. What do you think?

[Jim Michael]

Continuous roll film and paper processors use fluid pumps (http://www.mcmaster.com/#circulating-pumps/=8gp42z) to recirculate the chemistry. The degree of agitation could be adjusted by changing the flow rate, or program a controller to do an agitate-sit-agitate cycle.

[Eric Woodbury]

Jay, this might fall under the heading of 'better is the enemy of good enough', but what the heck. There would be several worries for sonic agitation. One, you wouldn't want it so strong as to take the emulsion off the substrate. Two, you wouldn't want standing waves, so the frequency should vary within an agitation cycle. Three, sonic waves have no net movement, much like sound in the room doesn't generate wind. There is some 'useful' flow as the frequency gets lower, but for a dielectric with a higher mass, it would have to be lower yet -- so low that we would probably call it agitation. Four, higher frequencies have greater diffraction meaning boundaries will cast shadows or interference patterns.

As long as we're talking about crazy arse ideas, at what pressure does developer boil. Maybe the film could be placed in a vacuum chamber and have the pressure reduced to a point that the developer would boil and act like nitrogen burst, but without the nitrogen, or oxygen, for that matter.

[DanK]

Jay,

Alaska is a little too cold for me....I preferred land based locations, as I preferred the option of 'running' if needed....:)

The diaphragm type pump definitely sounds possible...of course volumes in relation to film size will play a big role....typically larger volumes will most likely see more random patterns...

Film hangers, just as the reels in smaller formats, will have a significant effect on flow patterns....more so, I would believe, with larger films....

I'd be concerned with something as simple as film notches changing the flow across the film, being in a closed system....not to mention hangers, or even scratches in a tank, but until it is tested, who knows....

Thanks,
Dan

[Jay DeFehr]

Eric,

I think between yourself and doughnuts, I've lost my enthusiasm for acoustic/vibration agitation. As for pressure boiling; if the bubbles aren't oxygen or nitrogen, what are they? Very interesting idea!

Dan,

Imagine all the concerns you might have if we were considering placing the film in a box and tilting the box in different directions, but that's essentially what happens in tray development. I might not be convinced it would provide even development if it didn't have a very long history of effectiveness. Still, identifying potential problems is a very important part of the conceptualization process. When I imagine all those ports, some sucking other squirting, and the alternating with the next stroke, it looks in my mind's eye like effective agitation. A transparent chamber with some dye added to water might reveal the flow patterns fairly well. I saw a tank used as a kind of aquatic wind tunnel based on the same principle. I suspect the dye would very quickly disperse into a homogeneous fluid. Maybe some kid of micro beads would work better? If I had a real lab, I could make a video of the beads circulating, and use motion tracking software to model changes. Hahahhaha.

[Henry Ambrose]

Not to burst your agitation bubbles but........

Won't it be lots easier to move the film?

[Jay DeFehr]

Jim,

thanks for the link. I definitely like the idea of having the option of both automation and intermittent agitation, but I also like the idea of the chamber itself acting as the pump. Hey aqualung!

[DanK]

Dan,

Imagine all the concerns you might have if we were considering placing the film in a box and tilting the box in different directions, but that's essentially what happens in tray development. I might not be convinced it would provide even development if it didn't have a very long history of effectiveness.



Very True...and I learn more and more each time I tone or bleach a print, as I can actually see my agitation faults...

Actually that might be a good testing platform - dense print in a weak circulating bleach solution, see the actual effects....hmmmm

Experiment with various flow regimes and see the results in daylight....hmmm hmmm :)

Thanks,
Dan

[DanK]

Not to burst your agitation bubbles but........

Won't it be lots easier to move the film?


:) I agree



Thanks,
Dan

[Jay DeFehr]

Henry,

Not necessarily. Moving the film requires a lot of space, and exposing film to air during development is definitely not an advantage. Imagine a box roughly the size of a standard 8x10 tray that could be used to develop a dozen or more sheets of 8x10 film, using a small volume of solution, with some level of automation. Wouldn't that be cool?

[DanK]

Henry,

Not necessarily. Moving the film requires a lot of space

Maybe we just need to redefine 'moving' ....

Think outside the box, paradigm shift, etc...

Maybe?

Thanks,
Dan

[Jim Michael]

I haven't been following the thread but you might consider for your approach to drive the agitation from two membranes placed at offset points to set up more or less a anharmonic oscillation to minimize some of the limitations others have noted. Use a drop of color dye in the tank (clear plex for R&D) to get a better idea of the physical movement of the fluid. Sounds like an interesting project.


Jim,

thanks for the link. I definitely like the idea of having the option of both automation and intermittent agitation, but I also like the idea of the chamber itself acting as the pump. Hey aqualung!

[mmmdoughnuts]

Henry,

Not necessarily. Moving the film requires a lot of space, and exposing film to air during development is definitely not an advantage. Imagine a box roughly the size of a standard 8x10 tray that could be used to develop a dozen or more sheets of 8x10 film, using a small volume of solution, with some level of automation. Wouldn't that be cool?

I think that I might have missed the train on contributing to this one...

For many reasons, I don't see an elegant solution using acoustics or vibration. These concepts are very predictable and there for have predictable energy paths. Acoustic pumps like the ultrasonic pump in the humidifiers, and all pumps for that mater, would cause currents to form and stagnant regions to form causing uneven development.

Using acoustics in your pump as described in the animation, would cause standing waves to form in the fluid, which by definition, means moving locations of the fluid and non-moving locations even with the superimposed DC flow. With the pump pushing fresh fluid from the input it would become more exhausted before it left. All of it causing uneven development.

My understanding of nitrogen agitation is that it is random, the bubbles have different sizes and trajectories. Tray agitation, patterson orbitals, and tank development all cause mostly random large scale movements of the fluid keeping the solutions from becoming locally exhausted.

I think your quest is noble and would be greatly appreciated when solved, but usually the simpler solution will always be better.

Thanks for the thought exercise though! It isn't every day that I can use both of my hobbies together.

[Jay DeFehr]

Dan,

you're absolutely right! I was being narrow minded, and assuming I knew what Henry meant by "moving the film". Thanks for the reminder!

Jim,

The dye in the tank is definitely a very user-friendly, instant feedback approach, and would be very good for prototyping. I think using paper and a weak bleach is also a great idea for testing as the apparatus evolves.

I'm imagining a kind of wormhole scenario, in which fluid is sucked from one location and ejected at a remote location, like the opposite corner of the box. There would be multiple wormholes, the number and location to be determined by testing (unless someone has some advanced modelling software they want to exercise). When the diaphragm moves, the solution in the chamber circulates according to the number and placement of the wormholes, producing a random flow pattern. That's one idea.

[Jay DeFehr]

Doughnuts,

I've given up on the acoustic/vibration idea and moved on to a membrane pump and artery model. Very organic!

[mmmdoughnuts]

Doughnuts,

I've given up on the acoustic/vibration idea and moved on to a membrane pump and artery model. Very organic!

Still need to worry about stagnant flow on edges and corners. Let turbulence be your guide!

Cheers,
Andy

[Jay DeFehr]

Andy,

I really appreciate your expertise! I'm thinking the flow and turbulence could be manipulated by the placement of the ports/wormholes/arteries. I'm wondering if it would be better to have more smaller arteries, or fewer large ones, or some combination?

[evan clarke]

Put a tank on a rocking platform stirrer, there are several varieties, dependent on what kind of motion is required, orbital or side to side and the speed is variably controlled..EC

[Struan Gray]

I too would favour a rocker. There are lots of homebrew ways of arranging a slow rocking motion if you don't want to pay for a laboratory grade device.

However, another option would be something like a Nova tank and an agitator like the ones found on school science ripple tanks (see here (http://en.wikipedia.org/wiki/Ripple_tank)). The agitator shakes the film clip/hanger. You can change agitation force and frequency by playing with the power supply and counterweight, or go the whole hog and use a stepper motor with USB-based controller.

[Jay DeFehr]

Evan,

I don't think rocking a tank with hangers would provide adequate agitation. I think you'd end up with something like the Paterson Orbital Processor, which requires films to be laid flat, and not stacked, like tray development.

Struan,

Thanks for the link! Very interesting. This premise seems simple enough to test, and my new DR is a lot more amenable to these kinds of experiments than my old, micro DR was.

[Henry Ambrose]

The model I'd try to follow is that of a gentle moving at some intervals. The movement speed, duration and interval between would be slightly adjustable. For sheet film, the pick up, tilt, drain and drop technique using hangers and tanks done carefully is mighty hard to beat. Letting the developer sheet off the film in alternating directions defined by tilt gives very consistent results.

You could do a drain and refill but the aerial oxidation thing might prevent use of a few developers - but not most. And its gonna be super swirly. And still its easier to move the film.

I think the kind of agitation that has been proven to work will be very hard to duplicate using the direction you're going. "Cocktail shaking" is out for nearly all film developer combinations I am aware of. You'd think it'd work fine but there is always turbulence from the tank or the film holding device. It shows up in higher edge densities trays when the trays are too small. And the faults show up more as the velocity of the developer over the film increases. So low velocity is likely a good thing.

In my experience, enough proper gentle agitation, long enough rest intervals and a longer time in the developer are the major factors in getting great, even results.

[Jay DeFehr]

Henry,

The more I think about it, the more I'm leaning towards the heart/arteries model than the vibration model. I can make a simple tank and test for even development. I'm thinking now about pumping mechanisms. I think a double chamber pump would be required. It's beginning to take shape in my mind, and I'm optimistic about it's potential effectiveness. I want to keep it as simple as possible, but I want to allow for some automation, as well.

[Brian C. Miller]

Jay, what about a cheap fish tank pump? The little ones cost $15 or so. Have the tank drain into a sump, and then pump the developer back up over the film, using something like a sprinkler head. Ta-da! It's the film shower!

[Jay DeFehr]

Brian,

I actually have one of those pumps! I'm interested in circulating the solutions, more than draining and filling, though that's important, too. I wonder if a reversing pump would provide more random flow patterns?

[Henry Ambrose]

Or pump through some kind of mesh or filter to diffuse the flow.
I'm thinking of a bottom filter for a fish tank pumping in reverse.

But.....
Might there be a problem of a boundary layer at the emulsion?

How about the fish tank bottom filter that reverses, alternating push and pull, then resting for a while then repeating. Push - pull - push - rest - pull - push - pull - rest and so on.

How about a bottom filter on each end of the tank? One pulling the other pushing then reverse and rest and repeat.....

[Jay DeFehr]

Henry,

I'm thinking along the same lines. I think reversing the flow of the pump would go a long way toward eliminating flow patterns, and diffusion devices might help, too.

[jp]

Use a bigger container, then you won't have irregularities caused by the edges so close to the film. Bigger more consistent area.

[Jay DeFehr]

But, a bigger container means a larger volume of solution, which is a compromise. The challenge is to keep the solution volume low while providing adequate agitation for even development, and allowing for some automation.

[Brian C. Miller]

Engineer a species of fish that can swim in developer, and then their movements in the tank will provide random agitation for the film. You'll either solve all polution problems or produce monsters the likes would have left Dr. Frankenstein speechless! :D

Or you could have just enough developer to spray it on the emulsion side of the film with the fish pump method. You'd have to use Rollo Pyro, though.

[Jay DeFehr]

I've actually thought about the spray-on developer! That's a different subject. They use spray on developer for rapid processing of motion picture film, which develops in a fraction of a second, so no need to worry about agitation!

[Nathan Potter]

You folks are gravitating toward several concepts that are used in the semiconductor industry that I am familiar with. That industry is fanatical about uniformity over a wetted surface.

Spray developers are used to develop images in very high resolution photosensitive novolac resins at extreme resolutions in the submicron range. Uniformity of linewidth across a 12 inch diameter wafer is paramount and +/- .01 micron is not unusual. In this case the wafer surface is rotated about the center while a sheet of developer is sprayed from an above fixed tube that extends across the wafer. The spray of developer that reaches the wafer surface then sheets off the edge of the spinning wafer. The main advantage of the technique is that fresh developer is continually reaching the wafer surface and the reaction products are being constantly carried away. There are numerous variations but you get the idea.

Another analogy to film development can be found in the precision plating that has been developed for via fill at the copper wiring layer for microprocessor interconnect. These vias are submicron and must be filled with copper quite evenly and cleanly. For this purpose a variety of what's called fountain platers have been developed. The arrangement is exemplified by a pumping of the plating fluid through a perforated head comprising an array of tiny holes in a plastic sheet (teflon or other plastic), with the wafer in fairly intimate contact (variable), the array of holes facing up and the wafer surface facing down. The flow rate can be varied but is generally quite slow. The bath is recirculated and filtered. The technique is used for copper, gold and other metal plating baths. Precision wet etching is done in a similar way. In plating there is an electrical depletion region present as a thin layer above the wafer surface which has much to do with the quality of the plated layer but I would suspect that there is not quite the analogous effect with film development. In all of the film development schemes there will be no flow at the surface of the film so for some very small distance reaction products will be transported to the bulk fluid by diffusion. The reaction products will however cause a concentration gradient that will result in local uneven development in the form of edge effects but not long range uneven effects. Someone above mentioned using a wire mesh which got me thinking about some of these ideas.

Anyway a few more thoughts from a different technology.

Nate Potter, Austin TX.

[Jay DeFehr]

Wow! Thanks, Nate! I like the turntable development scheme! Another form of rotary agitation. If the turntables were stacked, multiple sheets could be developed. I wonder how closely they could be spaced?

[Henry Ambrose]

Hell Nathan, I've been doing stuff like that in my garage for years.

[Nathan Potter]

Well, yes Henry, but not to such a high degree of resolution for film photography. A lot of these high tech ideas can be implemented with inexpensive consumer junk from places like Home Depot, etc.

Jay, the turntable idea would need to use a vacuum hold down for the film - a bit of a complication for inexpensive home build. Stacking would be very complicated and hardly practical. Both methods mentioned above are more suitable for single sheet development.

A larger question is why bother with such sophisticated apparatus when the seemingly crudest of current techniques work adequately: tray development by shuffle, dip and dunk, etc. I've not followed this since inception but it's interesting discussion.

Nate Potter, Austin TX.

[Henry Ambrose]

Nathan,

I was kidding.

"very high resolution photosensitive novolac resins at extreme resolutions in the submicron range."

say what???

[Brian C. Miller]

A larger question is why bother with such sophisticated apparatus when the seemingly crudest of current techniques work adequately: tray development by shuffle, dip and dunk, etc.

But Nathan, what are we supposed to do with all of these old record players, fish tank pumps, and shower heads? And what about the old stereo with the 8-track player in it? Those speakers would make a great acoustic oscillation source!

Does Tri-X develop better to 1812 oveture, Ride of the Valkeries, or disco funk?

[Jay DeFehr]

Nathan,

Your question is a fair one. For my part, it's mostly mental playtime. When I puzzle over something, I tend to want to talk about it. There's a strong argument made by linguists that talking is essential to thinking, and writing is the same as talking, linguistically and cognitively (while thinking appears to optional for talking/writing;) ). The membership here is a deep reserve of knowledge and experience over a surprisingly wide range of specialties and expertises, as you yourself demonstrate, all bound by the common thread of photography. If the LF community was a corporation, it would encourage, or even mandate these kinds of brainstorming sessions to precipitate the innovation that is the life blood of competition.

We are currently experiencing a paradigm shift in photography, and those firms involved in suppling equipment for film photography are scrambling to define a strategy that most often involves phasing out of film based photography and into digital imaging, the result of which is a stagnation of innovation for film photography related products and processes. Stop the presses! I know we're all painfully aware of the current conditions, and I don't mean to be so obvious, but I think we, as a community have an opportunity to define the terms of our occupation by the incoming regime. In other words, I don't think we have to be content with what's offered to us, and we should feel free to imagine and innovate for our own purposes, without profit motives of feasibility studies.

It's so easy to hobble our creativity with practicalities, the challenge becomes not to think more rationally, but less so! The time for practicality comes later. I am awed by the quality of contributions to this little thread; both from the breadth and depth of experience behind them, and the creativity in them. I'm sure that if the LF forum had a Special Projects Division, it would produce spectacular results!

To address your question more practically: Automation with small solution volumes. Jobo offers one solution to the problem, and there are others, even more complicated, but I wonder if there's another way.

Thanks for all your contributions, and I hope to see more!

[Nathan Potter]

Henry, I just assumed you were some kind of a techie geek like me. After looking at your website I see you're human. BTW I like your FUN images - sort of on the vein of my recent FUNK project.

Brian, don't get me wrong. I'd suggest recycling that gear for photo applications, but I'd leave the music for listening.

I understand your motives Jay and thanks for a bit of a different kind of thread. Clearly a number of people here think in innovative ways. I think some, like me, do so because we were brought up poor and if we wanted things beyond bare necessities we had to innovate and make them. It certainly went for the early photography I did. First developing was done in the blackened milk shed on my grandfathers farm in Concord MA. about 1942. Farm about a mile from Walden Pond - OMG; was Thoreau still alive then! Used a few old milk cans cut and bent into trays. I found that the radius of the round can would rock nicely and provide more even development for the Verichrome film. I suppose I should post my first LF?, 31/2 X 51/2, size image (1942) here when I get around to scanning it.

Nate Potter, Austin TX.

[Brian C. Miller]

Right! Lay the film developing bag down on that old loudspeaker woofer, and crank up Play that Funky Music White Boy! A couple of tunes, and your development is done. And that old stereo with the 8-track is saved from the landfill.

Of course, you'll have to possibly deal with irate neighbors, but what the hey, people just gotta appreciate your art, right? ;)

[Jay DeFehr]

Van,

Are you kidding me?! This actually works? And with no air space? This is fantastic! I was convinced it wouldn't work! I HAVE to test this!

[Jay DeFehr]

Jay,

Give it a try, it is stunning how aggressive it agitates. Amazing how fast the sediment raises from the bottom and reaches the top of the bottle. It really is a small tornado. You may need to adjust the vibration rate, but once you got it...wow.

No more lifting tank from water bath to invert, and far more effective considering most tanks are almost full, so the splash effect has limited effect.

What this means is if your Kinderman stainless tank is completely full, there is no agitation taking place other then the little amount from the stainless reel sliding back and forth inside the tank as you invert. Watching the performance in a clear bottle proves it. Bonus is that it removes bubbles, which is why dentists and chocolate mould makers use a vibrating table.

Have you actually used this technique to develop film?

[bob carnie]

After quickly reading this thread, I cannot help to remember the Calumet Nitrogen burst system we used for developing colour prints.

Basically a big basket with all kinds of plennems(not sure if this is the correct word) that would fire off bursts of nitrogen into the basket as it sat in all the chems.
Worked very well for prints , but never tried it for film.
this basket was used for 8x10, 11x14, 16x20 and 20x24 cut sheet colour paper.

A mesh was inside to hold the prints and a hose hooked the basket to a burst system and walked the basket through the chems to final wash , then dried the basket and start over.
We had three or four baskets so as to not have any down time.
1972-76 time line.

[Nathan Potter]

I'm making a bit of a guess here, but a vibration table may not yield the same effect as moving developing fluid over the surface of film. I suspect that the aggressive motion of particles one sees from external vibration is the result of kinetic energy being transmitted through the fluid to the particles but does not significantly move the fluid volume from one location to another so would be deficient in bringing fresh solution to the surface of the film. How much this matters would be the subject of experimentation.

The actual displacement of the fluid would be a function of frequency so at the low end, a few Hz, (audio), displacement would be high and at the high end, (say ultrasonic, > 50 KHz), the displacement would be tiny.

Nate Potter, Austin TX.

[Jay DeFehr]

Excellent point, Nate. I wonder how much fluid is actually moving? I think the bottom line is: will vibration provide the energy necessary to develop film evenly. It might be that only the fluid in a very thin layer against the film is disturbed. This might be enough to prevent streaking, but not enough to refresh the developer at the surface. I don't know. I think we assume a lot about what's necessary based on what works, and that might rule out potential solutions.

Bob, that's very interesting. I'd never heard about nitrogen burst for print development. And the plenum idea is similar to my artery analogy. Something else to consider! Thanks for posting.

[Jay DeFehr]

Van,

I will definitely try this when I get home! In the meantime, theorizing will have to do, and won't affect the results of my trial. The Morse tank line sounds interesting, and I was recently wondering why nothing like it has been made. Thank you so much for sharing your experience and suggestions.

[Jay DeFehr]

Thanks for the link! Morse seems like my kind of fellow. I've always been fascinated by innovators and inventors, whatever their field. I've been fighting an urge to buy a Morse motion picture film developing outfit for some time now, as I have no real use for one, but maybe buying one will inspire me to find a use for it.

[Brian C. Miller]

This is a dream system for 5x7, because I don't think anyone (JOBO, Yankee, Doran, etc) making a 5x7 system.

The Jobo 3006 expert drum covers 5x7.