Tray Processing in Tubes
A Simple and Cheap Approach to Rotary Processing


©Copyright 1989 thru 2008 David Kachel

Article First Appeared in Darkroom & Creative Camera Techniques in July/Aug 1995

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When I was young I was one of those photographers you try to avoid whenever possible. You know the type — I knew it all, and I had plenty of sage advice for everyone, whether they wanted it or not. Worse, I had read Ansel Adams’ Basic Photo Series and I thought no one else had. In some cases I suspected I knew more than Ansel.

This was especially true when it came to the subject of sheet film processing. So when I bought a 4x5 view camera, I opted to ignore Ansel’s advice about processing sheet film in trays, and instead purchased a small rectangular daylight tank for sheet film. The manufacturer’s literature assured me that I was indeed the smarter–than–Ansel fellow I thought I was, because, according to them, their tank would give me flawless, evenly developed negatives without the mess and tedium of tray processing. Did I like the sound of that? You bet!

It was horrible. That daylight tank produced the worst development I’ve ever seen, before or since, from any kind of approach, anywhere. In fact, I don’t know of a single instance where sales hype differed more from reality. Unevenness was so bad that my negatives were useless, including those containing no sky or other smooth–toned areas. Repeated attempts to get acceptable performance from this tank produced not the slightest improvement in the results.

Somewhat humbled, I decided to cede this one point to Ansel. I bought some 5x7 trays for sheet film processing, and I’ve been processing my sheet film in trays ever since.

Along the way, however, I’ve tried just about every new gimmick or gadget to come along, both cheap and expensive, in the hope of finding a better way. I’ve used small tanks, deep tanks, hand tanks, rocking agitation, inversion agitation, nitrogen burst agitation, and the old Kodak standby of lifting hangers from the open tanks and tilting them to either side. I’ve tried nearly every conventional alternative, and the results have always been the same: awful! It seems unavoidable that the channels in reels or holders for sheet film will produce uneven development or bubbles along the edges of the film and that other structures in the tank, holder, or reel will cause uneven agitation and development. Apparently, structures of any kind, whether holding the film or just in close proximity to it, will produce uneven development. This makes tank development of sheet film a guaranteed losing proposition, by definition.

Aside from tray processing, there are only two other approaches that actually do the job right:

One is the Jobo “Expert” drum. I haven’t used this myself, but John Sexton, who owns and uses one, assures me it is excellent. In this case —considering the source — I feel it is safe to ignore my usual rule against anecdotal evidence and accept what he says. Well, the Jobo may be a great system, but I’m a “working poor” photographer, not a heart surgeon, and for me it’s out of the question. Even if it were more affordable, the Jobo system probably wouldn’t be the right approach for me, because it doesn’t allow individual sheets of film to be pulled out while others continue to process — an important part of the way I work.

The other approach is using Phil Davis’ BTZS tubes. I haven’t tried these either, but they are based on a concept similar to both the Jobo Expert drum and the technique I’m getting ready to relate to you, and, again, a number of people whose opinions I value have told me they work well, so I think it is safe to concede the point.

Unlike the Jobo Expert drum, Phil Davis’ BTZS tubes are readily affordable for just about any photographer. So why look for something else?

And for that matter, if I got good results with tray processing, why look at all?

I’ll go with the second question first. While it’s true that tray processing yields results vastly superior to most other approaches, that doesn’t mean it’s perfect. Until now it has just been the least of numerous evils. It tends to develop the edges of a negative slightly more than the center, and can sometimes produce unevenness or mottling (though this is seldom severe). Far worse is the risk of scratching or gouging the emulsion by constantly handling the negatives. This wasn’t much of a problem when I used Plus-X and Tri-X Professional — these films are hard to damage on purpose, let alone by accident — but when I switched to T-Max 100 and 400, I started having trouble. With these films, my tried–and–true tray shuffling technique produced severe scratches and gouges far more often than what I considered to be acceptable.

It wasn’t long before I realized that all it takes to scratch these otherwise flawless films was a hard look! I was either going to have to revert to Plus-X and Tri-X, or find some way to process sheet film other than in trays.

The search was pretty easy. Aside from trays and tanks there is only rotary processing. If a sheet of film is curved inside a tube, there is essentially nothing but pressure holding it in place — no channels or other structures to produce currents that result in uneven development.

Rotary processing of sheet film has been around for a number of years now and works fairly well. Development is more even than is the case with tray processing, and there is little risk of damaging the film in handling.

The Jobo Expert drum and Phil Davis’ BTZS tubes are the two basic choices when it comes to rotary processing. The BTZS tubes are intended for lights–on use, having end caps in which developer is placed before loading. The tubes are then tipped over and rotary agitation begins. They work, and they’re affordable.

The reason I didn’t go with them is that I’m not crazy about the idea of fiddling with those end-caps all the time. I use a number of techniques which would require introducing new chemicals into the tubes in total darkness before proceeding. Pre-soaking or employing a SLIMT bleach prior to development are examples. To say the least, this would be very awkward.

Also, I often process a lot of sheet film from a day’s shooting and the thought of measuring out small quantities of developer for each individual sheet of film is not very attractive either. I am also not convinced of the wisdom of development in the relatively small amounts of solution usually associated with rotary processing systems. In my opinion, most cases of uneven development or mottling associated with rotary processing can be traced to the small volume of chemistry allowed by the rotary tube.

I needed an approach to rotary processing that would permit me to use quantities of developer similar to those employed in tank or tray development so as to be sure of the availability of an adequate volume of developer. I also needed to be able to change solutions quickly without fumbling in the dark with small parts and without having to measure numerous small volumes of solutions in advance.

One thing I did not need was an approach which allowed me to work in room light. To me, it makes no difference whether I am standing at the darkroom sink agitating film with the lights on — or off. Either way, I have to stand there, pay attention to what I am doing, and keep an eye on the clock. Room light isn’t a big advantage.

In other words, I needed a way to make rotary processing in tubes work for me. I found it, and it is quite simple and inexpensive;

So here, adapted for my needs and maybe yours, is my “ultimate simplification” of the rotary processing approach:

My results from processing in this manner have been wonderful. There are no longer any scratches on my film. Development is significantly more uniform than that provided by conventional tray processing and I can continue to take the same basic approach to processing sequences I have always used. I am very pleased with this new approach.

Why the different lengths of tube? That’s easy. It allows you to process different types of film for different lengths of time without having to count or otherwise keep track of which film is which during processing.

Say, for example, you have six sheets of film to process — two for five minutes, three for seven minutes, and one for ten minutes. Put the five–minute sheets in the six–inch tubes, the seven–minute sheets in the seven–inch tubes, and the ten–minute sheet in the eight–inch tube. As each processing time elapses, it is easy to select the proper tubes in the dark by comparing their respective lengths, pull them from the developer, and drop them into the stop bath. This way you needn’t count, or keep track by other means while agitating, and can daydream until the first processing step is up. You do, however, have to remember which negatives are in which lengths of tube!

Another big plus provided by this approach is that, since it does not require the deft handling of film, one can don rubber gloves after loading the tubes, in order to avoid prolonged contact with potentially irritating chemicals.

There is one minor flaw involved in tube processing, whether by this method or any other. As mentioned previously, because the center of the reverse side of the sheet of film is pressed against the wall of the PVC tube, fluid cannot readily reach this area and the film is left with a broad water– mark down the center of its length.footnote 3 It is ugly and not removable, but cosmetic only — it does not show up in prints. I even tried making some grade 5 prints with a condenser head enlarger in order to give this water–mark every opportunity to show up on the print and it did not.

To minimize the water–mark, if you find it offensive, pre–soak in a mild Photo-Flo bath. You can also lift the center edges of the film during the pre– soak to allow water to penetrate more thoroughly to this area. Again, this water–mark does not show up on prints and is therefore of significance only to those of us who are compulsive perfectionists.

To test the effectiveness of this new approach, I tube–processed a number of sheets of film, all exposed to a uniform light source (my enlarger). I also processed one similarly exposed sheet by traditional tray methods, as a control.

I then printed all of these negatives on grade 4 paper (to enhance any defects) for a Zone VI gray tone.

Densitometer and visual measurements of the tube–processed negatives showed no variation in density whatsoever across the negatives.

Densitometer measurements of the tray–processed negative also showed no variations in density across the negative. However, it is a little–known fact that the human eye is more sensitive to density and color differences than the average densitometer and is therefore sometimes a more useful tool than the densitometer. Visual inspection of this negative showed a certain lack of uniformity from center to edge, along with some mottling.

The tube–processed negatives showed no scratching of any kind! This was of course, a highly gratifying result, because it was my primary goal. The prints made from all of the tube–processed negatives were significantly more uniform than the print made from the tray–processed control negative. Two separate test batches, consisting of six negatives each, were tube–processed. Density was extremely uniform across all of the negatives, both sensitometrically and visually. Within each group, all negatives in the group measured exactly the same density on the densitometer. Neither did they show any visual differences in density.

Conclusion

I’ve shuffled my last stack of sheet film. As soon as I realized how well this technique was going to work for me, I went back to the hardware store and bought a 20–foot length of PVC. For approximately a $10 investment (I already had the hack–saw and the razor knife.), I now have 40+ tubes of varying lengths and can process a substantial day’s shooting without stopping to wash or dry a tube.

I will continue to process film in trays but from now on, each sheet will be rolled inside its own individual length of PVC tubing. With this approach I get substantially more uniform development, no longer have to worry about scratches, do not have to count sheets as I’m processing, need to concentrate less on what I’m doing while agitating, and can continue to use any of the specialized techniques I have become fond of over the years. This is definitely the approach for me.

David Kachel