Mottled skies

[bgh]

I'm getting some odd mottling in the skies of several of my 4x5 negatives this year. I'm a bit flummoxed, as I can't seem to figure out why. I've attached a few scans from negatives over the past couple of months, all with different lenses, and no filters. There was a problem with controlling the water temperature in the darkroom, which I thought might be the source, but I've been keeping a much tighter control on the temperature, and I still get some funky skies. I'm processing with hangers in tanks, with the same agitation regimen that I've been using for years. The only thing that I can think of is that I've starting using Ilford FP4 and HP5 lately, after years of TMY, but I can't figure out what that would have this kind of effect.

Has anyone here had any experience with these kind of mottled skies? Any advice would be gratefully received.

With thanks in advance,
Bruce

[mpirie]

Bruce, It might help if you pass on the dev, dilution, pre-wash details etc.

Certainly looks like uneven development to me.

Mike

[Doremus Scudder]

If this is uneven development in the skies and not some mist/clouds that you overlooked at the time of exposure, then it really has to be an agitation issue. I don't work with hangers and tanks, so I can't give any specific advice there, but generally, make sure agitation is adequate at the beginning of the development and regular thereafter. Photo number 2 just looks like clouds to me, though...

Best,

Doremus

[bgh]

Bruce, It might help if you pass on the dev, dilution, pre-wash details etc.

Certainly looks like uneven development to me.

Mike

Thanks, Mike. I'm using Sprint chemistry, freshly mixed to the manufacturer's specifications. The negatives get a presoak of nearly two minutes (10 Hail Marys, to be precise...), then into the developer. Once in the soup, I agitate continuously for about 45 seconds (both up and down and forward and back), and then for 5 seconds every 30 seconds for the rest of the time. From there, one minute in the stop both with continuous agitation, then three minutes in the rapid fixer.

Thanks again,
Bruce

[bgh]

If this is uneven development in the skies and not some mist/clouds that you overlooked at the time of exposure, then it really has to be an agitation issue. I don't work with hangers and tanks, so I can't give any specific advice there, but generally, make sure agitation is adequate at the beginning of the development and regular thereafter. Photo number 2 just looks like clouds to me, though...

Best,

Doremus

Hi Doremus--

I agree with you and Mike, this does look like uneven development. I'm flummoxed by why, as I am using the same procedure that I've used for years, but only recently am I seeing skies like this. I will pay more attention to each step, and figure out if I've changed things.

Thanks,
Bruce

[mpirie]

I wonder if the two minute pre-soak isn't long enough for a traditional emulsion like FP4, compared to TMY?

I had to increase my pre-soak for FP4 to 5 minutes (25 Hail Mary's) from 2 minutes when i started with Pyro.

If the only variable you've changed is the filmstock, then it may be that FP4 needs to be handled differently from TMY?

Mike

[mmerig]

I wonder if the two minute pre-soak isn't long enough for a traditional emulsion like FP4, compared to TMY?

I had to increase my pre-soak for FP4 to 5 minutes (25 Hail Mary's) from 2 minutes when i started with Pyro.

If the only variable you've changed is the filmstock, then it may be that FP4 needs to be handled differently from TMY?

Mike

Ilford does not recommend a pre-soak for FP4. They don't say whether it is detrimental, or just unnecessary. I don't see any mottling, but I did not look very close. I would try a sheet on a plain subject, like a gray card, or white paper (underexpose to make sure you don't get maximum density everywhere). A well-exposed sheet of a gray card is handy to have sometimes when calibrating exposures during enlargements, so it won't be a totally wasted sheet of film.

[mpirie]

I've often pondered why Ilford would say that a pre-wash was unnecessary for FP4. Maybe they have some surfactant mixed with the anti-halation layer that would be washed out in a pre-wash.

Personally, since most of my work is done on Jobo rotary processors, i think a pre-wash is essential to avoid uneven development. It has to help development since it soaks the emulsion, washes out the AH layer and makes the take-up of the developer more easy and consistent.

When I started with Pyro and FP4, i experienced mottled skies and banding at the film edge. I upped my pre-wash from 2 minutes to 5 and the problem disappeared.

Mike

[bgh]

Ilford does not recommend a pre-soak for FP4. They don't say whether it is detrimental, or just unnecessary. I don't see any mottling, but I did not look very close. I would try a sheet on a plain subject, like a gray card, or white paper (underexpose to make sure you don't get maximum density everywhere). A well-exposed sheet of a gray card is handy to have sometimes when calibrating exposures during enlargements, so it won't be a totally wasted sheet of film.

As Mike mentions below, I've never quite understood Ilford's recommendation re: presoaking. I can try some test negatives without the presoak, and see how it goes. And thank you for the suggestion about the gray card for a test negative, I will try that.

Thanks again!

[bgh]

I've often pondered why Ilford would say that a pre-wash was unnecessary for FP4. Maybe they have some surfactant mixed with the anti-halation layer that would be washed out in a pre-wash.

Personally, since most of my work is done on Jobo rotary processors, i think a pre-wash is essential to avoid uneven development. It has to help development since it soaks the emulsion, washes out the AH layer and makes the take-up of the developer more easy and consistent.

When I started with Pyro and FP4, i experienced mottled skies and banding at the film edge. I upped my pre-wash from 2 minutes to 5 and the problem disappeared.

Mike

Mike--
Thanks for your multiple suggestions. Yes, i am beginning to wonder if the Ilford just needs a different approach than what I've been using for years with the TMY. The other option is just to go back to TMY, since I've been getting consistent results for years. Its just so darned expensive! Especially for a volunteer project. I have a part of a box of TMY, though, and likely will try shooting an FP4 and a TMY negative of each view when I go out tomorrow, and see how things look.

Thanks again,
Bruce