the minimum amount of D-76 needed

I have settled on D-76 1:1 for my B & W film developer, this works for me with Plus-X, Tri-X(400ASA), Tri-Xpro(320ASA), & HP-5. I recently started with 4X5 Tri-X and no time is given for D-76 1:1, does this mean that you should not use D-76 1:1 with 4X5 sheet film? This started me thinking about the minion amount of chemical that is needed to develop film. Kodak's estimated capacity gives the amount of film that a quart of D-76 can develop is 4ea 120 film rolls or 4ea 8X10. The smallest tank that I have is a Nikor 35mm tank with a 300ml capacity. Using Kodak's recommendation of 4 rolls/1000ml (yes I know that it is really only 946 ml), this gives me 250 ml for each roll but when it is diluted down to 1:1, it only has 150ml of D-76 developer in it. This is much less than the 250ml required by Kodak's estimated capacity but it works well. My questions are

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1) How much D-76 is the minimum amount for a roll of 120 or 8x10 area of film.

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2) Can I use D-76 1:1 for Tri-X 4X5 sheet film & what time do I give it.

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3) What happens to D-76 1:1 that you can not keep the diluted solution for a time before use?

If you want to be completely safe, you can follow the

guidelines in Anchell and Troop's _The Film Development

Cookbook. They recommend 250ml. of the stock solution per

8x10=1roll120=36exp.of 35mm.=4 sheets 4x5. So, if you dilute

the D-76, use a bigger tank. I believe that Kodak says that

you need a minimum of 100ml. stock. I've done it both ways,

and have done OK. When in doubt, I tend to go with the larger

amount; might as well use up the D-76 while it's fresh. I

just looked in the Kodak B&W Darkroom Dataguide and didn't find

dilute sheet film times, either. Someone should jump in with theat.

In any case, if you don't have the Anchell and Troop book, I

think it's a "must study." If you do, you know that they have

really worked it out!

You can check the "Massive Development Chart" at

http://www.digitaltruth.com

for development times of a multitude of films/developers. For Tri X

sheet film,it lists developing TriX sheet fime at ISO 320 in D76

(stock)for 5.5 min at 68 degrees. No listing is given for 1:1

dilution.

Here's my answer in a roundabout way...

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I frequently use D-76 1:3, often with 35mm HP5+, using 300ml per roll. I also use it with 120, 4x5 and 8x10.

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35mm x36 exp is about 80 sq in, same as a 120 roll, same as four 4x5 sheets. A 120 roll needs twice the amount of developer, and it's very easy to use more for sheet film, so 35mm represents the worst-case scenario.

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The amount of D-76 stock is only 75ml.

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In comparing HP5+ in D-76 1:1 and 1:3, given the extended development time needed for the higher dilution, I get identical EI, CI and curve shape. I get similar results for Delta 100.

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My conclusion is that 75ml D-76 stock has sufficient capacity for 80 sq in of film. I haven't tested any higher dilutions.

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A few tidbits...

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TX 120 is a _different emulsion_ than TXP, and the 4x5 film is TXP only. Development specs for TX may not be the same as for TXP.

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A reasonable guess for doubling the dilution (stock to 1:1, 1:1 to 1:3 etc) is to give 1.4X the initial development time. _This will probably need adjusting_.

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D-76 diluted 1:1 has only half the sodium sulfite concentration as the stock, which may allow faster oxidation than in the stock concentration. That's the only reason I can think of offhand that you probably shouldn't mix and store diluted D-76.

http://members.home.net/hmpi/Misc/Bascom/bascom.htm

this is an article written on using tmax with d76 1:1 i used the

times suggested and had excellent results.-J