Is there an equation for minimum developer per sq in/cm for non-mainstream developers?

Just perusing some old books on developing and some of them don't have any minimum developer amounts for various formulas.

Any formulas or rules of thumb for this problem?

Any examples or classifications of the formulas in question?

Not at hand at the moment

I will post some samples when I get home tonight.

I am curious as I have a 9x12 cm cut film tank holder that fits into a 1 liter Patterson 3 reel tank that will hold 6 sheets and I am beginning to suspect that 1 liter will not be enough for 6 sheets; which is about 100 square inches of film.

My Jobo 2000 tanks (pre rotary) use 1 litre of developer per 6 reel 5x4 holders, 9x12 is only a touch smaller. 1 litre is more than enough with most developers

When Ilford sold Hyfin a Highe Definition developer. and Kodak HDD, both needed 600ml per 80 80 sq inches of film (a roll of 35mm or 120, or 4 sheets of 5x4. In fact both developers came with 600ml sachets in their boxes. However High Definition developers are highly dilute with a highish pH, other developers like Pyrocat HD you'd be fine with around 100ml per 5x4/9x12 sheet.

If you use a replenished developer then quantity isn't an issue.

Ian

Ian Grant said:

My Jobo 2000 tanks (pre rotary) use 1 litre of developer per 6 reel 5x4 holders, 9x12 is only a touch smaller. 1 litre is more than enough with most developers

When Ilford sold Hyfin a Highe Definition developer. and Kodak HDD, both needed 600ml per 80 80 sq inches of film (a roll of 35mm or 120, or 4 sheets of 5x4. In fact both developers came with 600ml sachets in their boxes. However High Definition developers are highly dilute with a highish pH, other developers like Pyrocat HD you'd be fine with around 100ml per 5x4/9x12 sheet.

If you use a replenished developer then quantity isn't an issue.

Ian

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Thanks Ian. Can I assume you tend to use it one-shot or do you replenish?
(Edit: Sorry, I was in between jobs and didn't read carefully enough. Got it.)

I used to use Xtol replenished, these days I use Pyrocat HD as a 1 shot, it oxidises more so can't be replenished.

Ian

I suspect the issues I had with Pyrocat-HD were to do with mixing the developer up and then leaving it for a few hours before processing. More recently I've been trying out T-Max 100 in Paranol-S (Rodinal-a-like) and have been much stricter about more immediate use of the working solution.

Pyrocat needs using within a few minutes of mixing, as do other staining developers/

Ian

I found Pyrocat very good with Delta 400, not a film I've always found particularly easy to match to a developer. I don't have any Pyrocatechol however to mix up a fresh batch.

Kino said:

Just perusing some old books on developing and some of them don't have any minimum developer amounts for various formulas.

Any formulas or rules of thumb for this problem?

Click to expand...

Required development capacity by film surface is an elastic parameter... in theory the developer dose should be able to develop all developable silver in the medium to obtain film DMax in every spot in the frame.

In practice usually only a fraction of the silver is developed so usually only a fraction of the developer is required, but dosing developer in excess holds chem concentration stable so development is more consistent.

So IMHO it depends, if we produce thin negatives then we require less developer, for bullet proof negatives style way more developer is required or usually recommended.

What we can test is development capability, with samples of a certain film, lights open, we may fully develop the samples with different doses of developer and measuring the density reached by the samples, in that way we may compare developing capability of different developers, this does not explain all effects, of course, but this tells what relative safety margin we have with different developers at different doses.

I guess that tabular grain films require less developer than classic cubic films for the same results, as grains are flat a higher density may be reached with less developed silver, so with less developer consumption.

Kodak with Xtol recommends starting with at least 100ml of developer per 80sqi (a 120 roll, or 135-36, or four 4x5 sheets), this is a conservative amount... when I made a mistake using 2/3 of that I found no difference, but if we have specially dense negatives (say a lot of surface in Z-IX) then it would be interesting to see the effect.

Kino's post is well worth reading, When Kodak states that so many ml will process so much film it is the MINIMUM amount required. The minimum does not always equate to the amount required for a great negative. For decades I developed two 35mm rolls in a 500mm take with either D-76 or XTOL (1:1). Reading something akin to Kino's post a few years ago I switched to 1 roll in a 500mm tank and got more consistent results.

The issue of minimum developer quantities is particularly pertinent to Jobo rotary processing due to the smaller volumes used. For reference 5ml rodinal type developer or 10ml Ultrafin (making 250ml total solution) seems ample for a medium speed film in my experience.

beemermark said:

a few years ago I switched to 1 roll in a 500mm tank and got more consistent results.

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More "consistent results" is a bit elastic. Before spending a x2 dose of (one shot) developer by routine you may empirically measure you consistency gain.

A reliable way is using Film Control Strips (pdf attached) that can be included in each development. My experience is that accuracy in temperature, agitation, mixing and developer freshness would be way more critical for consistency than doubling developer dose, for two years I included those strips in my development batches to later check with a densitometer what was happening.

Now that I shot LF I learned that developing consistence is not that important, I started figuring that after being aware that I was widely modifying development times when developing N-3 or N+1 !!! At the end with VC/MG paper we will nail the the contrast grade we want by 0.5 grade or less (VC head, split grade) in the printing. If we scan then it's even easier.

In my experience most important factor to nail our visuaization is spot metering each interesting area and being aware about where those spots would fit in the sensitometric curve, more or less deep in the toe, in the linear section, in what region of the shoulder or at what density if our curve is linear in the highlights, knowing in advance how easy/difficult printing that will be from our film/processing.

As you will know as a view camera user, LF practice is a good teaching because rather bracketing a shot many times two equal exposures are taken to have a backup, this may command a refined metering and processing schema.

What I suggest is that if you are often processing N+/- your sheets then you modify your curves in a way that effect of doubling the developer dose won't be relevant at all, but anyway what would enlight this matter is using FPC strips, for having an empirical awareness.

Sorry, I could not get to posting an example of a specialty developer last night, but I will try again tonight.

I am pretty sure the sheet film adapter I am using inside a Patterson 3 reel tank will need to be filled to capacity due to it's design, but I understand that the Jobo Reels can use less chemistry with constant rotation.

In fact, it just occurred to me that my Jobo 2509 reel can adapt to 9x12 (forgot that!) and takes 6 sheets as well but fits into a 2521 tank with only 270ml capacity!

Now THAT really sounds dicey as far as developer starvation, but I must be paranoid...

Anyway, I will try again tonight.

OK. A couple of interesting formulas from Haist's, "Modern Photographic Processing".

G.W. Crawley solvent-type formula; FX-9?
Sodium sulfite (anhydrous) 100g
Chlorohydroquinone 7.5g
Diethyl-p-phenylenediamine sulfate 7.5g
Water to make 1 liter

5 to 11 min @ 68F

or

P.K. Turner's M.C.W. 1 solvent-type formula
Metol 2g
Hydroquinone 5g
Sodium Sulfite, desiccated 100g
Borax 2g
Sodium thiosulfate pentahydrate 3g
Water to make 1 liter

Time to develop given as "essentially the same as D76". Said to give slightly less emulsion speed than D76 and about half the graininess.

How to you determine, other than risking multiple sheets of film, how many square inches of film can be developed by a liter of each solution?