Diafine: Help please for uneven development

[Ken Lee]

I've used the same gallon of Diafine now for around 20 4x5 negatives over 2 weeks, and today I got this result, in spite of continuous agitation. No pre-soak.

Would Photo-Flo solve this problem - or does this irregular development indicate some other problem ?

[Wayne Crider]

I've had Diafine give me uneven development but far worse then yours. It was almost like the emulsion didn't soak the A solution up very much in some areas. First I question your continuous agitation since with Diafine you don't do that, so I don't know what that's about. I can tell by the shadow of the reflector on the wall the light is coming from the left and a little higher thru a window; I can see the reflection in the pan, and I also can see density in the reflection partly being the bulb, and since the umbrella is higher the shadow is more in line. The only area I see that looks strange is the left wall shadow up high. Is there any chance in a million that you didn't see this and got what was there or the light was filtered by something outside or reflected off something inside? Can't black satin(?) reflect a shadow? The other thing that comes to mind is how large open areas of a sky might give problems. It might be a wall with some texture but it's very homogenous being one color. So, just some ideas from a Diafine user.

20 45's shouldn't be a problem with a gallon of Diafine if it's reasonably young, and for Diafine young can be a couple of years depending on usage.

[Renato Tonelli]

I have gotten uneven development also and only with constant agitation (Jobo); I could only conclude that Diafine is not well suited for constant agiation (I might have also read about it). It's a pity because I use it quite often.

[Leigh]

...today I got this result, in spite of continuous agitation.

That's your problem. Diafine wants very limited gentle agitation. It's a compensating developer.

Per the box instructions: "Agitate very gently 5 seconds initially, then 5 seconds each minute thereafter.
The bold-faced very gently is in the original instructions, for emphasis.

No pre-soak is correct. It will inactivate the developer.

Photo-flo would do nothing as it's used after development and fixing are completed.

Diafine lasts forever when replenished per the instructions. You need to keep a quart of unused solutions for this.

Replenishment is done by adding enough fresh Solution A to replace the volume lost (measure the volume), then
adding an equal volume of fresh Solution B to its container. Discard any excess used Solution B.

Replenishment can be done at any time, so you can do it now to add the previously lost volumes.

I've used Diafine for several decades with very uniform results. I really love it for tray development (4x5 & 8x10).

- Leigh

[Ken Lee]

I made 2 exposures of that scene, and here's the other negative. It show less streaking, but development is still blotchy.

Sorry for the confusion, but all the sheets I've tried over the last weeks have been continuous shuffling agitation in a deep tray, and this is the first time I've seen uneven development. This time I developed 12 negatives in the same batch, 4 min + 4 min. Could there be something about the presence of 12 sheets rather than 6 ?

With Divided Pyrocat, we add Photo Flo to Solution A to help absorption: it's very effective. See http://www.largeformatphotography.in...ting-Developer

I'm reluctant to add Photo Flo to the Diafine Solution A: I don't want to spoil it accidentally.

[Leigh]

I don't see anything wrong with your process. I normally do a maximum of six sheets in a batch, but if you're comfortable with handling 12, I see no reason why it wouldn't work properly.

Depending on solution depth there might be insufficient developer in contact with each film.

Photo-Flo is a surfactant (i.e. soap), designed to reduce the surface tension of water, allowing it to run off a negative rather than beading up during the drying process. I have no idea why it would affect developer absorption.

- Leigh

[Ken Lee]

Perhaps I'm wrong, but with less surface tension holding the water molecules together, they can more easily migrate into the emulsion. A wetting agent makes water more... wet, no ?

I will try using more volume. Meanwhile, I'm hooked on 2-Bath developer: there's something very smooth going on.

[Leigh]

Yes, it makes water wetter. My problem is determining how that would affect uptake in an emulsion.

Perhaps it does.

- Leigh

[Ken Lee]

From Encyclopedia Britannica (emphasis added)

Wetting Agent:

also called surfactant, chemical substance that increases the spreading and penetrating properties of a liquid by lowering its surface tension—that is, the tendency of its molecules to adhere to each other.

[Leigh]

I know the definition. I don't know how it would affect uptake.

- Leigh