Kodak D-76 8x10 in Expert drum

[PengNuo]

Hi guys,

so far I have been using d-76 1:1 without any issues for 4x5 in Jobos expert drums. However, now that I have upgraded to 8x10 I was wondering about the developer capacity.
Kodak states max 4 sheets of 8x10 in 1l full strength developer and 2 sheets at 1:1

Given that I would like to continue using 1:1, how would you adjust the developing time (%) to account for the developer exhaustions if I want to process 4 and / or 5 sheets in one drum at the same time?

thanks in advance

Alex

[Rick A]

Developing times should remain the same as with 4x5, only capacity has diminished (not really, it's a square inch equation). One 8x10 has the same square inch area as four 4x5's.

[PengNuo]

Hi Rick,

what I meant was, that for 4x5 I dont have to worry for developer exhaustion because I can pour enough solution into the drum. Maybe I have reformulate my question: If I would like to keep 1l solution of 1:1 and develop four and / or five sheets of 8x10, by how much (percentage) should I increase the development time?

[ic-racer]

According to your first post, 1 liter of 1:1 will only process two 8x10 negatives. You would not need to change your time at all for each two sheets processed.

[PengNuo]

@IC-racer but I want to process 4 sheets at the same time in 1l at 1:1

[ic-racer]

@IC-racer but I want to process 4 sheets at the same time in 1l at 1:1

Wanting and doing are not the same
Seriously, I believe many issues with uneven development (uneven sky etc.) are from developer exhaustion. What I do is err on the side of 20% to 50% capacity safety factor. Tmax developer is 50 to 60 cents per sheet if only used to about 50% capacity, whereas the T-Max film cost $10 per sheet.

[PengNuo]

Wanting and doing are not the same
Seriously, I believe many issues with uneven development (uneven sky etc.) are from developer exhaustion. What I do is err on the side of 20% to 50% capacity safety factor. Tmax developer is 50 to 60 cents per sheet if only used to about 50% capacity, whereas the T-Max film cost $10 per sheet.

Fair enough. A pack of D-76 is 88¥ here which is roughly 13$. At 16 sheets capacity it doesnt really break the bank. Luckily GP3 is still rather cheap here at 2$/sheet of 8x10.

[Jim Noel]

@IC-racer but I want to process 4 sheets at the same time in 1l at 1:1

The developer is going to exhaust at a faster rate because of the 4x larger surface area. Once exhausted, no further development will occur. That's what "exhaustiion" means.
I suggest you try 2 sheets with a 10% increase in time and check the result. if you are satisfied , try 3 sheets. I believe you will see severe underdevelopment by this time.
In other words, I don't believe you can put enough 1+1 developer in the tank to develop 4 sheets of 8x10.
If you attempt to put more than 1.5 liters of developer in the tank it gets to the point of overflowing, and run the risk of overloading the motor.

[mpirie]

Surely developer exhaustion would be related to the image density?

If you are trying to calculate number of sheets processed before exhaustion is reached, you are likely to be disappointed by the inconsistent results.

It might be better to restrict the number of sheets/square inches of emulsion done at the same time to make sure you stay away from exhaustion?

Mike

[PengNuo]

@mpirie: good point about image density. Didnt consider that aspect!