[pure-silver] Re: film capacity of stock D-76


----- Original Message ----- From: "Tim Daneliuk" <tundra@xxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Cc: "Eric Nelson" <emanmb@xxxxxxxxx>
Sent: Wednesday, February 01, 2012 7:28 AM
Subject: [pure-silver] Re: film capacity of stock D-76


On 02/01/2012 09:14 AM, Eric Nelson wrote:
I'd do some kind of replenishment with that kind of system. That way you can keep processing without worry.

Seems Kodak discontinued d-76-r so you'd have to find out the formula from them or somewhere. i snagged the last few bags i could find of them online and i'll bet there's none now.

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*From:* Bogdan <bkarasek@xxxxxxxxxxxx>
*To:* pure-silver@xxxxxxxxxxxxx
*Sent:* Wednesday, February 1, 2012 5:56 AM
*Subject:* [pure-silver] film capacity of stock D-76

Hello all,

I've done a Google search and can't find a satisfactory answer.

Yesterday, I developed 20 8x10 sheets of Tri-x 320 (iso 200) in a stock solution of D-76 using a 3.5 gal tank and film holders (a first... used to do the tray card shuffle).


I have 16 4x5 sheets of Efke PL 25 Ortho and 4 sheets of 6.5x8.5 sheets of T-max that I want to develop today. Question is, can I continue using the same tankful of D-76 or is it exhausted and do I have to prepare a new batch 0f D-76 to do the Efke and T-max?

Cheers,
Bogdan K

Kodak says the capacity is 16 8x10s/liter of developer

However, if you replentish, you can extend this considerably. I do this by mixing two gallons of D-76. One is my working developer, the other my "replentisher" - Kodak did/does make a D-76R for this purpose, but I never bothered. I keep the replentisher in a cubtainer so that as I use it, the
remainder is not exposed to air.

There are a number of ways to determine how much replentisher to use, but I use the lazy man's way: After each development sessions, I fill the working D-76 gallon back up to the rim of its container with fresh D-76 from the cubetainer. Using this method I have gotten around of year
of useful life out of a gallon of D-76.

HOWEVER ... I typically only do 3-4 8x10 equivalents at a time. Given the volume you're doing you may want to be more aggressive in replacing the old developer with the new. You might start with something like 1oz of fresh D-76 for each 8x10 equivalents. Pour that into the working container first, and then fill it back up to the rim with working developer when you're done. You'll likely end up with left over working developer in the tank doing things this way, which you can just toss out.

I don't think this is super critical so long as you are regularly adding fresh
developer to the working solution.




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Tim Daneliuk

The technique of self-replenishment seems to work for some newer developers like T-Max RS and Xtol. The older replenisher formulas usually had an abundance of developing agent and alkali in them. I think part of the reasoning was to compensate for the accumulation of bromide which tends to suppress shadow development. Long ago Kodak Labs published curves showing the effects of use on shadow detail. I no longer remember where this was published but think the Journal of the SMPE sometime in the 1930s. I also can't remember when replenishing formulas begain to be used. I have to re-read some old stuff. FWIW here is the formula for D-76R, the D-76 replenisher formula. Some photographers used it for push processing.

Kodak D-76R
Water (at about 125F or 52C).................750.0 ml
Metol..........................................3.0 grams
Sodium sulfite, desiccated...................100.0 grams
Hydroquinone...................................7.5 grams
Borax, granular...............................20.0 grams
Water to make..................................1.0 liter

The instructions for small tank use say to add 1oz of replenisher solution to the empty developer bottle and then fill it with the used developer. Any replenisher should be added at a rate that keeps the developer activity constant. Note that one alternative formula for D-76 includes 0.25 gram/liter of potassium bromide. This has the effect of _increasing_ effective film speed slightly by suppressing the fog characteristic of the developer. I have never seen any research on the effect of bromide from the use of the developer but since that has other effects perhaps the same effect does not take place. However, the curves published in the research report do show a suppression of shadows where developer is re-used even when the development time is extended to maintain the gamma. Since D-76 and its variations were very widely used by the motion picture industry I suspect an abundance of sensitometric data exists somewhere.

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Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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