How much developer in a rotary developer?

[bags27]

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Thinking about splurging on this:

https://www.catlabs.info/product/filmomat-light-compact-manual-rotational-film-processing

How much developer to use? How much time? I've heard that one cuts down on time by around 12-15% but mainly it's trial and error. There doesn't seem to be a lot of data available.

Edited September 9, 2023 by bags27

[Pyrogallol]

A rotary tank probably uses less than normal as the tank is on its side and rotating so not full up with liquid?

But it seems a big lump of equipment just to develop a film. Any time saved developing will be wasted setting it up and cleaning up afterwards. As well as the space it takes up. 

I did think about something similar for processing colour prints in the past. I used a print drum on a roller base for colour prints then found it is ideal for developing sheet film, b&w. That 8x10 drum rotates on its side and only uses 80ml liquid, but it is only developing a sheet not a spiral.

 

Edited September 9, 2023 by Pyrogallol

[BernardC]

7 hours ago, bags27 said:

How much developer to use? How much time? I've heard that one cuts down on time by around 12-15% but mainly it's trial and error. There doesn't seem to be a lot of data available.

It depends on the tank. For instance, the Jobo Multitank 5 needs 640ml of solution. That's one of their supported tanks, but there are others.

You'll need to experiment for development times. Some datasheets give a different time for rotary development. Remember that these are just starting times, and you can adjust them to suit your process and preferences.

In my case, I've found that I hardly need to adjust the dev time with a rotary processor. That's because of two factors: my preferred hand agitation is already vigorous, and I use a very dilute developer (Rodinal 1:60) which is exhausted at the end of processing. I think that I would need to shorten the dev time if I used D-76/ID11 at default dilution, or if I had dialed-in my inversion-tank process for very weak agitation (or stand development for an extreme example).

 

[St Pete Darkroom]

What I fail to see in my readings regarding HOW much developer to use when Rotary processing is.....If you use too little developer, the developer may exhaust during the process, then what, can't fix that.

My question is and I can not find an answer to it is, is there any harm in being conservative and use a lot of developer (the heck with the saving developer cost already) when Rotary processing?

I have been using a lot more developer than recommended. I fill the tank up on its side with water, and see how much it will take before it would leak out, then I measure that in a measuring beaker and use that much Developer to develop. Sometimes if I have a very tight fitting lid, I will use a bit more.

Then I set the Rotations per minute slow, to about 30 to avoid thick contrasty negatives as you might get using vigorous inversion agitation.

The negatives sparkle, but Im curious if anyone has had negative (no pun intended) effects from using a very full developing tank on a rotary processor.

cCn you email me back with your feedback, as I most likely will never find this thread again in this lifetime.

RobertCoscia23<at>gmail.com

[TomB_tx]

I've used Rotary processing with both B&W and Color (C41) with both Jobo and Patterson tanks, using about 60% of rating for inversion processing. I've never noticed a capacity issue with both dual tanks (120 size) or 35mm single reel tanks with 36 exp film. With Patterson that means only 250 ml - same as I use in a single reel stainless (Nikor) tank.