Developing Control Strips in Hand Tanks

I'm trying to get a better handle on actually controlling/monitoring my B&W processing, and to that end I have bought one of the popular(and now inexpensive) X-rite sensitometers to hopefully use in conjunction with my densitometer.

In thinking through it, though, let's say I were exposing 35mm film on the step wedge in the sensitometer, in which case I think I'd cut about 6" of film and expose it. Presumably then this would be loaded into a hand tank and processed using my normal time/temp/inversion for that film.

I primarily use stainless tanks and reels, and I know agitation is highly dependent on turbulence from the developer moving around in the tank. With 120 film, you'll always fill the spiral completely unless you've loaded wrong, and even a 24 exposure roll of 35mm will fill all but the last couple of turns of the spiral.

It would seem to me that if loading say a 6" strip on a spiral, the fluid flow dynamics would be a LOT different than if the spiral were mostly or completely loaded with film.

Is there some measure that should be taken with a control strip to be sure it sees agitation like a full roll? Would it be good practice to take a developed blank roll(cut to say a 30 exposure length) and load it on the spiral with the control strip, or even splice it to the control strip? I realize too that one could just use a full roll of film and expose the step wedge on one end of it, but that would certainly waste a lot of film unless you were actually shooting the rest of the roll.

Does anyone have any thoughts or experience with this? Am I overthinking it? The Kodak process manuals I've referenced, such as Z-133, are geared toward large tank and/or machine processing, so don't seem to offer any real insight into this.

It would be best to process your control strip along with other film in a normal development environment. I'd try to simply tape the control strip on the end of another roll on the same reel. If there's enough room on the reel for the extra length, no problem. If not, you may have to shoot a short roll and clip off six inches (four or five frames would need to be sacrificed at the end of the roll). Then simply process normally.

Hope this helps,

Doremus

Why don't you just expose the strip on the head of a 36 exposure roll of film without cutting it and shoot the rest of the roll normally?

If you want your test wedges to match your actual processing, then like Doremus says, attach it to some of your normal film.

Good idea by Kino as a routine check. I used to occasionally do this if I had an unfinished roll that I wanted to process asap.

A note about where the strip goes... I'd guess that the results MAY vary depending on where the test wedges go. So... might be worth exposing test wedges through the entire roll of film, including reversing the direction of the wedges.

If you really just wanna study the "condition" of the developer under various test regimes, try this: tape your test strip against the inner wall of your SS tank (use a short strip of tape at the leading and trailing edges). Then use a magnetic stir bar; 1.5 to 2 inch should be fine. (Obviously no reels in the tank.) To process, load the tank and pour in developer. Right away set it on top of a magnetic stirrer and dial up the speed to whatever preset point you want. (If the stirrer is already going the stir bar may just chatter, etc.)

Yeah, I do have plenty of experience with this. We used to test color developer mixes like this, screening just about every one. We used to do it inside of a precision lab temperature bath to keep the developer temperature on the money. A typical Corning magnetic stir plate had no problem driving the stir bar through the clear plastic tank of the lab bath. My very vague recollection is that the results weren't an exact match to the actual processing machines anyway, so we just decided decided the heck with starter solution, etc., and just tested with the color developer replenishers straight up as mixed. (All we wanted was to verify consistency of each mix, as proof of the proper mixing and no contaminants in the chems.)

As I recall we tried the control strips in both directions and found no difference, but I could be wrong (this was something like 45 years ago). We did this with both color film and color paper developers (about 5 or 6 fresh mixes daily) for lots of years. It was a very good way - easy to set up and very consistent, to screen developer mixes.

FWIW we started this routine as part of a larger project - scratch mixing the paper developer AND "regenerating" same. The predecessor of the RA-4 color paper process, Ektaprint 2/3, was AgBr based, and very susceptible to bromide ion in the developer. So Kodak had developed a regeneration scheme based on use of ion-exchange resin (Rohm and Haas IRA-400, as I recall) to remove primarily the bromide. We had a custom-made system for this, and after a basic chemical analysis the treated developer was reconstituted with the missing components. Because there are so many ways to screw up, we figured the most straightforward screening method would be to actually process a test strip, which is how we came about doing this. Fwiw we initially bought a Jobo rotary processor specifically for this purpose, and had it plumbed into our QC darkroom. But using it was such a slow and tedious process we came up with the Nikkor SS tank routine and got rid of the Jobo. Fwiw the RA-4 process came out shortly after this. RA-4 paper is AgCl based, and the chloride ion had very little effect on the color developer, so we scrapped the entire ion-exchange system (but it essentially had paid for itself in the first 4 months).

It’s all good. Cut six inch strip and process on its own reel, or expose test on the beginning or end of a roll.

Even if you expose tests all the way along a whole roll of film you’ll find outer edge gets higher contrast than the middle and the center.

I consider it part of the normal variation. The difference is significant but not enough to worry about. Todd-Zakia Sensitometry has a phrase that says it better but I can’t find it right now.

Do tests any way you are comfortable. In reality that test strip was processed with that batch of film (or on the same day).

Thanks everyone for the thoughts and information.

I think that for an initial trial, as wasteful as it may be, I may just ~3ft of film off a bulk roll and do several test strips along its length. That way too I can see-as suggested-the change along the length of the roll. I know in the real world it's not a big deal for most purposes, but it's also nice to have numbers to know what I'm dealing with. I've bought a 100ft roll of Kentmere 100 specifically for this initial trial-I don't normally shoot Kentmere film, but as an Ilford product I'd hope it has the same QC/repeatability as "real" Ilford, and a single freezer-kept 100ft roll(I use a food sealer and a silica gel pack to seal bulk roll cans before putting them in the freezer to avoid condensation) should give me a consistent product to compare with enough to last a while.

In the future, @Mr Bill I love your suggestion of a strip taped inside a tank with a stirrer. I know that's not analogous to intermittent hand agitation, but agitation should be consistent/repeatable if always using the same stirrer and the same setting on it, and even if it doesn't exactly duplicate hand processing it gives me something to monitor developer activity over time.

As pointed out, even with my Jobo and tight temp control, the agitation and deverloper activity will be different for a single strip and my usual eight 35mm rolls in a big 1500 series tank. I leave about 6 exposures free at the beginning of the roll and leave the leader out. Then, in the dark, I have it all pre-measured to pull just enought film out of the casssette to get the sensitometer exposure in the right place to fill the six blank frames of a 36 exposure roll.

However, if comparing two films for response to a developer, I will pricess just the two strips together or separate with just the short strip in the tank.

I do something similar to @ic-racer

When I go out with four rolls, one of them I will mark the leader with the cryptic “6 for sens” and hit it with a test exposure.

If I finish the day near “30” I will hit the tail with a test exposure

My idea is to have a test exposure on every other run of film.

You are supposed to keep track of the “hold time” which is the time between exposure and development. I haven’t been doing that.