PMK, BTZS tubes and HP5

[Shen45]

I don't use PMK but a friend does and I would like to test some HP5 for him in my BTZS tubes.

The tubes hold about 70ml per 5x4 sheet [maybe 80 if you try hard].

Each tube is rolled for the duration of the development.

Does anyone use BTZS for HP5 with PMK and if so would you share your plotter file?

Steve

[Jay DeFehr]

I don't think PMK is a very good choice for rotary processing. Under ideal conditions PMK produces a lot of general stain, and rotary processing amplifies the problem significantly. I would consider another developer, or another development technique. Good luck.

Jay

[Brian Ellis]

I tried to use BTZS to test HP5+ with pyro. However, it was difficult to get consistent readings from my densitometer. In theory you're supposed to be able to use the blue filter in a color densitometer to read pyro negatives but it didn't work very well, I could read the same area three times and get three different readings, plus the readings didn't progress in the way they should. I use BTZS tubes normally but didn't with PMK because that's not supposed to be a good combination. I used trays. There's another type of pyro that's recommended for rotary processing, ABC maybe?, but I forget what it is. Frankly I was unimpressed with PMK and after untold hours of effort in testing, making duplicate negatives, processing one set in PMK and the other in D76, printing the results, etc. in an effort to see if PMK produced any benefit that couldn't be achieved with D76, I concluded that it didn't and for me it was more trouble than it was worth.

[Eric Woodbury]

There are several pyro film developers that may be less tricky than PMK, especially for rotary processing. I have never used the tubes you speak of, but have used a Jobo expert drum on my own base with PMK since the beginnings. I suffered through a lot of problems of getting the process even. With all the oxidization going on in a rotary process and the fact that the back of the film does not get even developer distribution, the stain on the back of the film is a source of unevenness. I fixed this by purging the tank of oxygen during development. If your tubes had no air in them, you might get this to work, but with no air, I'm not sure how well you can agitate the developer. Also, you should have enough developer with 70 to 80 cc, but that is close.

If you do try this, be sure to use the EDTA additive to PMK and prewet your film. I'd recommend a pyro designed for rotary processing or use trays.

[Jim Rhoades]

Oh, Brian. You should not have written that. You should know by now that PMK pyro is the developer that God himself uses. Before the pyroheads launch an attack, maybe you should see an Ellis print.

[Jim Noel]

Rollo pyro was formulated to use in rotary processing. The stain is very similar to PMK, but oxidation from agitation is not such a problem.
Many people also use Pyrocat HD or one of its derivatives in the tubes you mention.

[sanking]

I tried to use BTZS to test HP5+ with pyro. However, it was difficult to get consistent readings from my densitometer. In theory you're supposed to be able to use the blue filter in a color densitometer to read pyro negatives but it didn't work very well, I could read the same area three times and get three different readings, plus the readings didn't progress in the way they should. I use BTZS tubes normally but didn't with PMK because that's not supposed to be a good combination. I used trays. There's another type of pyro that's recommended for rotary processing, ABC maybe?, but I forget what it is. Frankly I was unimpressed with PMK and after untold hours of effort in testing, making duplicate negatives, processing one set in PMK and the other in D76, printing the results, etc. in an effort to see if PMK produced any benefit that couldn't be achieved with D76, I concluded that it didn't and for me it was more trouble than it was worth.

It is surprising that you had trouble getting consisent readings of pyro stained negatives with a densitometer. Over the years I have used several different densitometers to measure stained negatives, in both Blue and UV mode, and have never had a problem in getting consistent readings.

ABC Pyro is definitely not the staining developer you want for rotary processing. I think some of the confusion about this is because the original Rollo Pyro formula, which was provided by a man named Harold Leban, was called ABC+. That was, IMO, a very unfortunate choice of words because it suggested a plus version of the old ABC Pyro formula, of Weston fame, when in fact ABC+/Rollo Pyro is more like a supercharged PMK, with ascorbic added.

Sandy King

[Jay DeFehr]

Brian,

I think your densitometer was not properly calibrated. While I agree that PMK is not the best choice for rotary processing, that shouldn't affect the consistency of your measurements. Learning to exploit the benefits offered by tanning/staining developers requires a long term commitment, like everything else worth mastering, and I fault no one for choosing another path.

Steve,

There are several very good staining developers from which to choose, and I don't see any advantage in trying to make one of them perform outside it's design parameters. If you want to use rotary processing, it makes sense to me to use a developer that is compatible with that process, rather than trying to make one compatible by reformulation or elaborate oxidaton prevention schemes, and conversesly, if you want to use PMK, it makes sense to me to use it in the way it was formulated to be used. Good luck.

Jay

[Andrew O'Neill]

PMK didn't work well for me in BTZS tubes. I tried the rollo version and it was much better...what will your friend be printing on? For me, rollo developed HP5+ negatives didn't print well on VC paper (forte polygrade V)...but that was just me.