Developer CAPACITY question

[Jeroen]

Here’s my situation:
I’m using Ilford Perceptol as a developer. I really like Perceptol - 30 years ago I got great results on FP4 and FP5 (135 and 120 format). So now that I’m cautiously returning to chemical photography (I hate the term ‘analogue’), Perceptol is my standard and I’d like to stick with it at least until I can achieve my former technical levels, but now on 8X10" film.

Now, Ilford states that 1000ml of stock solution has a capacity that’s good for 5 sheets sized 8x10”.

My Jobo 4450 drum (rotary development in Jobo CPA) holds 4 sheets sized 8x10”.
But the beaker of the drum has a maximum capacity of 600ml.
According to Ilford, that 600ml can only develop 3 sheets of 8x10”, not 4…

So here’s my question:
What do you recommend with 4 sheets in the drum? That’s an increase of 33% beyond the developer capacity…
- Should I increase development times by x-percent? Is that going to work at all??
- Forget about the 4th. sheet?
- And what if I want to increase contrast for N+1 or even N+2 development? Maybe stick to 2 sheets max?

Of course I can & should & WILL do personal testing, that’s the only way to be certain, but I’d like to have a starting point and so I’d like to hear your recommendations.

[Jim Noel]

I would rather reduce the number of sheets than strain the limits of the developer. I would only develop 3 sheets to prevent developer exhaustion.

[Kevin Crisp]

Given the price of film and the time you invest in each sheet of 8x10 I’d go with 3 sheets. Unless you want to experiment.

[Sal Santamaura]

...Ilford states that 1000ml of stock solution has a capacity that’s good for 5 sheets sized 8x10”...

Where have you found that? To the best of my knowledge, Ilford's information on Perceptol is located in this document


https://www.ilfordphoto.com/amfile/file/download/file/1829/product/551/

where, on page 7, the description under "REUSING DEVELOPER WITHOUT REPLENISHMENT" clearly indicates 250ml of stock solution can develop only 80 square inches of film. Given that, which is consistent with many other sources claiming a minimum of 250ml metol-based developer stock is required per 8x10 sheet, I'd use 500ml Perceptol in your tank to develop only two sheets of film.

In my own experience, even 75% of the recommended minimum stock Perceptol will result in underdevelopment with "average" scenes, i.e. those having a typical distribution of brightnesses as opposed to predominantly low luminance, the latter being much less taxing of developer (but more of fixer).

As I've preached numerous times here and elsewhere, developing film with less than the specified minimum quantity of stock solution (regardless of developer dilution) might "work," but not predictably. Confidence or crap shoot; the choice is yours. :)

[Jeroen]

192935
Inside the Perceptol box it says '20 sheets 10x12,7cm' (=4x5"), so 5 sheets 8x10".

I have to agree with your 'sermon' on unpredictable results when developer gets exhausted in medium to high key scenes, so I'll take your advice and develop 2 sheets at a time. Thanks for your replies!

[Sal Santamaura]

...Inside the Perceptol box it says '20 sheets 10x12,7cm' (=4x5"), so 5 sheets 8x10"...That's a typo and should instead read "16." Right above it are the correct "4" for 135-36 and 120, each of which is 80 square inches just like an 8x10 sheet.

You're most welcome. I'm happy that someone agrees with my conservative approach to avoiding developer exhaustion. :)

[Vaughn]

You can also run a couple batches of developer -- two batches of 500ml of stock should handle your 4 sheets of 8x10 in the drum.

I do something similar to this with the 3006 drum and six 5x7 sheets of film.

[Jeroen]

Perhaps I can even enlarge the Job beaker to hold 1000ml so I can still develop 4 sheets at a time.
Sounds like a nice MYOG project :cool: