SP-445 agitation test results challenging

[Ulophot]

The following post is embarrassing to me, but I’ll survive, especially if a solution if found.

With a little vacation time recently, I finally got around to testing specifically for even agitation with the SP-445 tank, which I have been using for about two years. I had decided to test, even though I have been generally happy with image results from the start, only occasionally noticing a slight variation in large even-toned areas that left me wondering if something were a little amiss. I’m not a landscape-and-sky photographer, mostly; portraits or other more complex subjects that tend to hide such variations are my line. Someone will ask, then, why bother? Because it’s a simple, very basic matter and I don’t like settling for “okay,” least of all in matters of basic craft.

With larger film batches I use a Jobo tank on a roller for continuous agitation and get very even tone indeed. The 445’s low sheet capacity, however, is a great addition. I am not going to return to tray processing. Others report nice even results from the 445; it’s a valuable piece of equipment.

I have been using the proper broadside end-over-end agitation, although 4 inversions over 10 seconds every minute rather than every 30 sec., and in a slightly more continuous, rotisserie sort of motion than the faster “flip” approach demonstrated in the Stearman Press video. But I also tried that variation, and have tried agitating every 30 seconds. My results have been a bit disappointing in all cases, with a noticeable mottling. It’s worse with a very smooth, continuous inversion, and also with a pronounced “drop” or “push” at the mid- and end-point of each inversion cycle (i.e., over and back upright), rather than revolving strictly around an imaginary axis. A slight drop, my standard for decades with SS tanks and roll film, gave me the example shown.



My developer is D-23 1:1, nothing unusual; Normal development is 9 minutes at 68 F. I have questioned whether my two-plus-year-old Metol might be at fault, but that makes no immediate sense; overall densities have not diminished relative to exposure/development. It’s stored in brown glass out of direct sunlight, though the temp is often in the 80s in the summer. Anyway, the mottling varies from run to run and appears to be an agitation issue.

My test targets have been, variously, a large sheet of matte white card stock taped to my flat outside house wall under overcast conditions; two sheets of letter-sized copier paper taped next to each other on a flat surface and illuminated with bounced light; an area of rich blue sky. No variation across the field in any direction read by my spot meter in any of these cases.

I have tested with one sheet or two in the tank, both with emulsion toward the tank center, i.e., film loaded on inner side of holder(s) when holder(s) inserted; and with emulsion toward the outer tank walls from the outer sides.

The image shown, scanned from a contact print, approx. Grade 2 ½, is the best result I have managed to achieve after a half-dozen tests, still showing the mottling. The dark center line is a small space between two sheets of paper on my upright piano board, photographed out of focus.

The last time I recall having to struggle to get even agitation was back in the days of 35mm Tech Pan and Technidol (some of you surely remember that joy), which required a very quick ¾-inversion flip of the tank with no rotation a couple of times every 30 seconds.

Any ideas?

[Alan9940]

First, the only absolutely even development that I've ever found is obtained in Jobo Expert Drums on my CPP-2. I know this doesn't help you any with the SP-445, but I wanted to say that up front. Now...

Are you doing a pre-soak? What film stock? I've never done this kind of test with the SP-445 specifically--though I have with other development methods--but, I've never noticed any specific development issues from using this tank. The only issue I ever had was the occasionally gouge of the emulsion from one or two of the holder clips where the film feeds under. This was resolved by inverting the tank side-to-side. Have you tried that agitation technique? With the broad side of the tank facing me, I grab the center of the top and do an inline inversions x2. I pause for about a half second when the tank is inverted. For the next agitation cycle, I use my other hand and go the other direction. Does this make sense? Might be worth a try if you haven't exhausted all the possible agitation techniques already.

[Wayne]

First, the only absolutely even development that I've ever found is obtained in Jobo Expert Drums on my CPP-2.

Not even in trays?

[Alan9940]

Not even in trays?

Yep. I used tray development of 4x5 and 8x10 film for my first 15 years with LF and settled for what I got; not many other options available back in the 70's. Then, I moved on to BTZS tubes and they were okay, but I could only process 2 sheets of 8x10 at one time. When I got the Jobo and Expert Drums and saw what beautiful even development looks like, I gave up my trays and BTZS tubes. I do still use other methods of processing LF film, but these are for more "non standard" techniques whereby constant agitation is not desired.

[Ulophot]

Thanks, Alan.
HP5+, no pre-soak.
If I understand your agitation, it is explicitly recommended against by Tim at Stearman, so, no, I haven't tried it.

[Alan9940]

Thanks, Alan.
HP5+, no pre-soak.
If I understand your agitation, it is explicitly recommended against by Tim at Stearman, so, no, I haven't tried it.

Yep...that's me...do something that no one else is doing! FWIW, I don't use the SP-445 for "keepers" due to the issues I've had with it. I use it only for quick tests.

[Michael R]

I went through many experiments and found the "broadside" agitation to be best. I also had to experiment with different inversion speeds, etc. etc. The best results I was able to get were somewhat better than the image you posted, but still not good enough (for me). I also found it difficult to get reliable consistency, not only from run to run, but occasionally among sheets in the same run. I tried all the same things you did - different numbers of sheets, facing in, facing out. Combine all this with other issues and I had to move on. Just my opinion. Others might totally disagree.

[BrianShaw]

I do similar to Alan but not full inversion. Rock “slowly” narrow-side to left until near sideways, return to upright, continued to right until near sideways, return to center. Repeat a second time. Total agitation time about 10 seconds. The developer clearly gets mixed up if the sound of sloshing is an indication. Haven’t noticed any uneven development.

[Ulophot]

Slow sideways rocking is reminiscent of sheet-film-in-hangers agitation, which I know about from reading but never had occasion to try. Perhaps I'll try it, but I suspect it may significantly change my development time. Thanks for the suggestions, though; as advertised, I'm open.

[esearing]

In my early tests with PyroHD in the SP445 tank I did see some slight density difference top to bottom for an 1 minute initial agitation vs a 2 minute initial agitation with a shot of open sky. But I also learned at the same time a more dilute longer overall development was better than short development for my way of working. If you factor in Fill+dump times as a percentage to your overall process time, then it makes sense that more dilute taking longer gives more consistent results since those times my range from 15-30 seconds. I was never happy with HC110 1:31 because of the high contrast it gave in 6 minutes vs what it looked like using 1:63 for 10:30 (slightly less than double time). I also prefer a long 5 minute presoak with FP4 and HP5, Bergger 400 doesn't seem to matter. My agitation method is hand over hand for developer but for fixer i merely flip it around and rock it some because I use 30 second agitation periods then rest 30 second for 5 minutes.


If you have ever put photoflo in your tank you have to wash it with very hot water to remove the residue. It does impact development in the next batch.