Capacity of chemicals in small trays

Elmarc · Feb 7, 2025

Hello all,
I am about to change my tray size from 8x10 to 5x7. I usually use 1 litre of dev/stop/fix in each tray. The 5x7 trays will probably need 1/3 of this amount to sufficiently immerse the prints but I am wondering if the capacity of the number of sheets will change in the developer and especially the fixer. For example, my safety margin put through for 8x10 FB in the fix is normally 10 sheets to ensure maximum stability.
Your thoughts are always greatly appreciated.

snusmumriken · Feb 7, 2025

Elmarc said:
Hello all,
I am about to change my tray size from 8x10 to 5x7. I usually use 1 litre of dev/stop/fix in each tray. The 5x7 trays will probably need 1/3 of this amount to sufficiently immerse the prints but I am wondering if the capacity of the number of sheets will change in the developer and especially the fixer. For example, my safety margin put through for 8x10 FB in the fix is normally 10 sheets to ensure maximum stability.
Your thoughts are always greatly appreciated.

Each sheet will be 44% of your previous paper area, so why not use 440 ml of each solution and keep your previous safe capacity in terms of number of sheets?

Ian Grant · Feb 7, 2025

1 litre of developer in a 10x8 tray is too much really, I use around 1.5 litres in a 20x16 tray. Stop & fix I sue more and I have lids for the trays, I rarely use RC papers and with FB always use 2 bath fixing as this is more economic.

Ilford's figure for Rapid fixer is 40 sheets of FB paper per litre, with 2 bath fixing that can be higher with archival permanence.

Ian

Ian C · Feb 7, 2025

The capacity per liter is usually reckoned in terms of a given number of 8” x 10” sheets per liter. That can also be converted to area per liter. The given capacity assumes that the developer will be used to capacity within a reasonable time after mixing. The longer it’s exposed to air, particularly in a tray, the faster it will oxidize and deteriorate.

If your print developer is rated by the maker as having a 50-sheet-per-liter capacity (4000 square inches) and you’re making 5” x 7” sheets (35 square inches), that liter of developer can develop (4000 square inches)/(35 square inches) = 114 sheets of 5” x 7” paper. [Ilford MG developer @ 1 + 9 and using FB paper]

https://www.ilfordphoto.com/amfile/file/download/file/1828/product/709/

I recommend using plenty of developer in the tray, say a depth of 15 mm or more. At the end of the processing session, pour the developer back into its bottle to form a uniform mixture, recording the total throughput at that time.

If the results are good and you use the developer to capacity within a reasonable time, you should then discard it and mix fresh developer.

If, after using the developer over a considerable time or approaching its capacity, you notice overly long development times to attain the required density, or a loss of contrast requireing higher contrast filters than usual, the developer is exhausted and must be replaced, even if it hasn’t reached its claimed capacity. If the developer is accidently contaminated with fixer or stop bath, that will greatly weaken it and must be discarded at that point and new developer mixed fresh.

I agree with the comments in post #3. In my practice, I use only 2-bath fixing to ensure the complete fixing of films and prints.

Working in this manner, the capacity of your solutions will remain the same as stated by the maker. Developer is much more prone to deterioration due to exposure to air, or contamination than fixer or stop bath. Thus, developer might have less capacity than stated depending upon your working conditions. You must monitor the results and be ready to discard and mix fresh developer if the results become unsatisfactory.

Don_ih · Feb 7, 2025

snusmumriken said:
Each sheet will be 44% of your previous paper area, so why not use 440 ml of each solution and keep your previous safe capacity in terms of number of sheets?

That's a good, practical approach.

Elmarc · Feb 7, 2025

Don_ih said:
That's a good, practical approach.

I agree.

Elmarc · Feb 7, 2025

Ian Grant said:
Ilford's figure for Rapid fixer is 40 sheets of FB paper per litre, with 2 bath fixing that can be higher with archival permanence.

Ian

I was aware of 40 sheets provided by Ilford but I distinctly remember the general consensus being 10 after much research many years ago on this forum. I may have bookmarked the thread. Please correct me I am wrong.

Elmarc · Feb 7, 2025

Ian C said:
The capacity per liter is usually reckoned in terms of a given number of 8” x 10” sheets per liter. That can also be converted to area per liter. The given capacity assumes that the developer will be used to capacity within a reasonable time after mixing. The longer it’s exposed to air, particularly in a tray, the faster it will oxidize and deteriorate.

If your print developer is rated by the maker as having a 50-sheet-per-liter capacity (4000 square inches) and you’re making 5” x 7” sheets (35 square inches), that liter of developer can develop (4000 square inches)/(35 square inches) = 114 sheets of 5” x 7” paper. [Ilford MG developer @ 1 + 9 and using FB paper]

https://www.ilfordphoto.com/amfile/file/download/file/1828/product/709/

I recommend using plenty of developer in the tray, say a depth of 15 mm or more. At the end of the processing session, pour the developer back into its bottle to form a uniform mixture, recording the total throughput at that time.

If the results are good and you use the developer to capacity within a reasonable time, you should then discard it and mix fresh developer.

If, after using the developer over a considerable time or approaching its capacity, you notice overly long development times to attain the required density, or a loss of contrast requireing higher contrast filters than usual, the developer is exhausted and must be replaced, even if it hasn’t reached its claimed capacity. If the developer is accidently contaminated with fixer or stop bath, that will greatly weaken it and must be discarded at that point and new developer mixed fresh.

I agree with the comments in post #3. In my practice, I use only 2-bath fixing to ensure the complete fixing of films and prints.

Working in this manner, the capacity of your solutions will remain the same as stated by the maker Developer is much more prone to deterioration due to exposure to air, or contamination than fixer or stop bath. Thus, developer might have less capacity than stated depending upon your working conditions. You must monitor the results and be ready to discard and mix fresh developer if the results become unsatisfactory.

Good advice, I always record how many prints including test strips go through the developer and also record the time that it takes for the image to appear and judge exhaustion that way. Easier to do with developer than fixer. In my experience MG developer expires very quickly. I used Tetenal developer (until they went bankrupt) and Moersch which has a very long life as a working solution.

MattKing · Feb 7, 2025

I expect that the arithmetic/linear calculation might not apply exactly, because the differences in geometry mean that carry-over and oxidation won't necessarily behave in the same way.
But results are your friend.
Use manufacturers' "per square inch" guidelines - perhaps with some extra safety factor, if you prefer.
Then carefully compare image emergence times in the developer, and use the available checks for complete fixation, to check your real world results.
Personally, I prefer having a decently generous amount of liquid in my trays.

Elmarc · Feb 8, 2025

MattKing said:
I expect that the arithmetic/linear calculation might not apply exactly, because the differences in geometry mean that carry-over and oxidation won't necessarily behave in the same way.

This is the part that I could not envisage let alone calculate!

MattKing said:
Personally, I prefer having a decently generous amount of liquid in my trays.

Me too. I may settle with 440ml as suggested by Snusmumriken and see how that works. 5x7 paper in an 8x10 tray seems a little wasteful. Plus the smaller trays will take up much less space in my very small darkroom.

Don_ih · Feb 8, 2025

I don't like 5x7 trays - at least the ones I have. They spill too easily because they're not very deep. Maybe yours are deeper.

MattKing said:
I expect that the arithmetic/linear calculation might not apply exactly

That's probably correct and I'd expect the developer would be oxidizing more quickly in the smaller tray with the smaller volume (but same amount of agitation).

GregY · Feb 8, 2025

Elmarc said:
This is the part that I could not envisage let alone calculate!

Me too. I may settle with 440ml as suggested by Snusmumriken and see how that works. 5x7 paper in an 8x10 tray seems a little wasteful. Plus the smaller trays will take up much less space in my very small darkroom.

I only use 5x7" paper occasionally but prefer to use 8x10 trays, I find it easier to maintain 20C temperatures with more volume.

Doremus Scudder · Feb 8, 2025

Ian Grant said:
Ilford's figure for Rapid fixer is 40 sheets of FB paper per litre, with 2 bath fixing that can be higher with archival permanence.

Ian

Elmarc said:
I was aware of 40 sheets provided by Ilford but I distinctly remember the general consensus being 10 after much research many years ago on this forum. I may have bookmarked the thread. Please correct me I am wrong.

If one reads the tech sheet on Ilford Rapid Fixer or Hypam carefully, you'll find that Ilford gives a capacity of 40 8x10-inch prints fiber-base per liter for "a high level of image permanence for commercial use," but recommends only 10 8x10-inch prints per liter for "maximum stability." This, assumably, is for single-bath fixation. Two-bath fixation would about double the capacity for either standard. I like 35-40 8x10s per liter of bath one with a two-bath fixing regime. That means one gets 20 8x10s per liter total before one promotes bath two to the bath-one position. After doing that a few times, the economy is even better. This is fixing to Ilford's "maximum stability" standard.

Here's the relevant paragraph (emphasis mine) :

"If a high level of image permanence is required
for commercial use the silver concentration in the
fixer should be kept below 2 g/l when fixing FB
papers. This approximates to 40, 20.3 x 25.4
cm, (8 x 10 inch) FB prints. Above this level
compounds may remain in the paper base after
washing and over time possibly contribute to print
staining. For prints that need maximum stability for
long term storage a the maximum silver level in
the fixer should not rise above 0.5 g/l i.e..
approximately 10 20.3 x 25.4cm (8 x 10in)
prints."

As for volumes in 5x7 trays: Paterson 5x7 trays will easily hold 600ml of solution - I do it all the time. If I were the OP, I'd figure that a 5x7 print is close enough to half an 8x10 to just use 500ml of solution in the 5x7 tray and halve the capacity (or, just use the same number of prints for through put capacity, e.g., 40 8x10s per liter = 40 5x7s per 500ml).

Capacity is capacity; it just needs to be adjusted for volume and print size to get numbers for a specific print size and/or solution volume.

Best,

Doremus

GregY · Feb 8, 2025

Elmarc, ....a second thought...... I invariably find that i splash more out of the trays w 5x7" than with bigger trays.....while trying to maintain agitation.

MattKing · Feb 8, 2025

I nest the 5x7 trays in empty 8x10 trays.
8x10 trays in empty 11x14 trays.
11x14 trays in empty 12X16 trays.
Drips and spills are caught, there is a good space for tongs, agitation of the trays is actually easier and it actually is easier to pour out chemicals into bottles at the end of a session.

Capacity of chemicals in small trays

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