D-76 Coverage

[Pawlowski6132]

Kodak Technical Publication J-78 for D-76 addresses coverage like this, "You can develop...(80 square inches) in...(16 ounces)...of diluted developer."

It doesn't address coverage for full strength developer.

If I assume diluted developer is 1:1 and, undiluted is full strength, then can I assume that coverage for 80 square inches is 8 ounces?

thanx

[David de Gruyl]

If I assume diluted developer is 1:1 and, undiluted is full strength, then can I assume that coverage for 80 square inches is 8 ounces?


Yes. (Under development times on page 2).

The development time changes, though, if you choose to use D76 1:1 at lower volumes / roll. It is kind of silly to specify that you need twice as much D76 1:1 as D76, when you are theoretically reusing one and tossing the other.

Personally, I think you are better off using the 1/2 amount and adding a little time to your development. Or doing a development test at different times, if you have a bunch of film to waste. Kodak recommends 10% additional to use the right size tanks for the amount of film. (240 mL (8 oz) / roll).

(I assume this is about 8x10 sheet film: I have had no trouble with 8 oz of D76 1:1 to develop a single sheet of 8x10).

[Heroique]

Kodak has some useful specs about D-76 here (http://www.kodak.com/global/en/professional/support/techPubs/e103cf/e103cf.pdf?id=0.1.16.14.30.14.7.14.16&lc=en).

For example, if you're processing in a tray or tank, the chart says D-76 (at stock or "full" strength) is good for 16-8x10 sheets per gallon.

And at 1:1, it's good for 8-8x10 sheets per gallon. This, BTW, translates to 5 square inches per ounce, and appears to confirm your Kodak J-78 publication ... or 16 oz. of 1:1 for one 8x10.

These are merely "official" specs; your darkroom habits might introduce variables, as mine often do.

[David de Gruyl]

These are merely "official" specs; your darkroom habits might introduce variables, as mine often do.

That sure is the truth. For all of us.

This is from J-78 (page 7, but it is the same as what is said on page 2).



To extend the useful capacity of D-76 Developer diluted
1:1—when processing two 36-exposure rolls in a 16-ounce
tank—increase the recommended time by about 10 percent.


Basically they list the times and capacity for what they are specifying (using twice as much as you actually need) and then tell you how to do it to get twice the amount of film processed.

If this were not possible, you would not be able to re-use stock D-76.

You can get 32 x 80 square inches out of a gallon of D-76 using once through 1+1 dilution.

[Pawlowski6132]

Thanx all.

This may help explain the poor results I was getting in my development:

Current

-TMY2
-Rotary Tube w/ Bi-Directional Rotation
-8 minutes (Fred Picker PEI Test)
-D76 1:1
-68 degrees
-6 oz
-80 sq in (4neg @ 4x5)

Kodak Recommended:

-TMY2
-Rotary Tube w/ Bi-Directional Rotation
-6.5 minutes
-D76 Full Strength
-68 degrees
-8 oz
-80 sq in (4neg @ 4x5)

Lemme give this a whirl.

One more interesting points from the tech sheet;

1. Kodak doesn't give a recommended time for rotary tube processing at 1:1

[David de Gruyl]

One more interesting points from the tech sheet;

1. Kodak doesn't give a recommended time for rotary tube processing at 1:1

Nope, they don't. Typically you can reduce intermittent agitation times by 10-15% for continuous agitation. Whether this is a good idea is another story. (for Rodinal, it is a bad idea. I can tell you that much).

[Pawlowski6132]

Nope, they don't. Typically you can reduce intermittent agitation times by 10-15% for continuous agitation. Whether this is a good idea is another story. (for Rodinal, it is a bad idea. I can tell you that much).

Are you implying that the Rotary-Tube Processing times recommended by Kodak are for intermittent or continuous?

[David de Gruyl]

Are you implying that the Rotary-Tube Processing times recommended by Kodak are for intermittent or continuous?

Sorry, rotary tube processing times are always continuous.

what I meant was that tank developing time may be adjusted (downward by 10-15%) to use continuous agitation in a rotary tube. If it is available.