4-up film developing tricks?

[Richard Wasserman]

I have a small sink line with 1 gallon tanks that I want to use for processing 4x5 B&W and C-41. I just got some 4-up hangers and before I use them I am wondering if anyone has any helpful hints for insuring even development. I have read that some people can't seem to get them to work while others have no problems. I assume they wouldn't have been used for decades in labs is they didn't work properly. I'm hoping they don't require nitrogen burst.....

I've used single hangers with success. Any tricks of the trade?

[Gem Singer]

An effective agitation method: Lift the hangers and tilt them 45 degrees forward. Lower them back into the tank Then lift them again and tilt them 45 degrees backwards. Lower them into the tank and let them sit motionless until the next agitation cycle.

This operation takes about 15 seconds. Do it once a minute.

To decrease contrast, agitate every other minute.

[Jay DeFehr]

Lately I've been wondering about vibration as a means of agitation, as an alternative to nitrogen burst, rotation, or inversion. Not sure it's feasible, just mental wanderings. I imagine how convenient it would be to discover that agitation could be accomplished by vibration, and the degree of agitation controlled by the frequency and/or amplitude of the vibration. I've seen vibration cause ripples, and even violent disturbance on the surface of water, and wonder if it would sufficiently break up the boundary layer of developer on the film's surface. I mention these things on this forum hoping someone smarter than myself will confirm my suspicions, though I'm always skeptical when they dis-confirm them! Human nature, I suppose, or maybe just my own stubbornness.

practically speaking, I've always used the method Gem describes above, with good results.

[MIke Sherck]

The first thing that comes to mind regarding agitation by vibration is air bubbles. I'd be sure to test thoroughly, in light sufficient to view the surface of the film in processing, in detail. Perhaps there's a frequency and/or magnitude which works, or which doesn't, which I imagine would have to be established by trial and observation?

Mike

[Rick Moore]

I have used Gem's method very successfully. I add one other small thing - during the initial agitation, I lift the hangers about an inch and let them drop onto the tank rim a couple of times to dislodge any bubbles.

Jay: I have also wondered about this, specifically, using an ultrasound transducer to produce the vibrations.



--
Rick

[Jay DeFehr]

Then I'm not alone! That's good to know.

Mike,

I wondered about air bubbles, too; it's the first thing that came to mind. I don't think air bubbles are inevitable or unavoidable, but they're certainly a concern. I also wonder about patterns forming on the film. We've all seen (presumably) the ring pattern made by vibration (remember Jurassic Park?) on a liquid surface. I can imagine all kids of potential patterns, but I can also imagine ways they could be cancelled by alternating the wave forms, etc.

[Gem Singer]

When I was in dental practice, we used ultrasonic vibration with a solvent to clean our instruments. It was a very effective way to remove debris before sterilization.

I have the feeling that using that type of vibration for film development would eventually lead to separation of the emulsion layer from the film base.

The technique that I described calls for slow, gentle agitation, instead of violent shaking or vibrating, allowing the developer to exhaust in the denser highlight areas before refreshing it by agitating.

[Jay DeFehr]

Gem,

You make an excellent point! If vibration can separate the emulsion from the base, it ought to be able to disturb the boundary layer enough to effect a change of developing solution at the film's surface. Vibration need not be violent, or continuous, just sufficient. Maybe we're on to something!

[Mark Woods]

I find that the process Gem mentions works for 4x5 and 5x7 (most of the time), but totally causes edge build up in 8x10 (on hangers). I've thought about the ratio of movement of the 4x5 in relation to the 8x10. The 8x10 is double the movement and it shows up in uneven development. What I do now (besides the drop the hangers about an inch to dislodge bubbles), is to gently move the hangers right and left and alternate moving them up in a circular motion. Alternating each minute. Some may say that it's very similar to stand developing -- but taking less time. So far I've had very little if any edge build up on the 8x10 negs.

Hope this helps.

[mmmdoughnuts]

Gem,

You make an excellent point! If vibration can separate the emulsion from the base, it ought to be able to disturb the boundary layer enough to effect a change of developing solution at the film's surface. Vibration need not be violent, or continuous, just sufficient. Maybe we're on to something!

A few things to consider here. Surface waves on the top of the water (the ones that crash on the beach or ripple across a lake from a tossed stone), do not travel below the surface of the water. So surface waves are out for agitation of fluids around submerged film.

There might be some merit to a LOW frequency acoustic source producing enough agitation but what you are really after is fluid velocity and not acoustic pressure and you can't have large acoustic velocities (read fluid flows) with out large pressures. While velocities of sound traveling through water are very fast, they are different from the fluid particle speed resulting from the wave propagating and the particle speeds only localized. Plus, any fluid that moves from an low amplitude acoustic wave just returns to its exact same location. So there is very little agitation such that it would clear the surface of the film.

Ultrasonic cleaners are just for that - cleaning. Their energy is so large and at such a high frequency (ultrasonic) as to cause cavitation and micro bubbles. These bubble expand and collapse creating localized shock waves that remove the debris on surfaces. Technology aside, ultrasonic cleaners are out due to their destruction.

If you look at ultrasonic humidifiers, I think this might be the best possibility there. Their energy is large but not as destructive as a US cleaner. However, because their energy is still so great, as the energy leaves the acoustic transducer, the fluid is entrained with the energy and actually moves great distance. This might be the best acoustic solution.

But what you want is fluid flow that has a displacement that is the same magnitude as the film size. Remember we are trying to simulate the lifting of film out of water and returning it to the tank at an angle so the fluid swirls and mixes around the film holder as it is returned.

Acoustics is neat and also my job, but what is needed here is a propeller or pump or just a plain stick to stir the fluid.