Developing twelve sheets in a Combi-plan... without f*ckups?

[mortensen]

Hi

I have a couple of hundred sheets of Foma100, that I need to develop. I've been using my combi-plan tank for half a year being modestly satisfied... so I thought:

Shouldn't I easily be able to develop 12 sheets at a time instead of 6?

I ran four cycles today and none of them came out properly - giving me 48 more or less damaged negatives... no wonder I feel like a complete arse today.

Problems seem to be some kind of blue/green film on the plastic base, that doesn't wash off properly. I load the film back to back, emulsion facing outwards (of course) and keep it that way through fixing and washing... which is probably the problem, right?

On the last batch I ran a second wash i my sink with each negative at a time. They came out better and clearer, but this extra washing time almost ate the time saved by running a double batch. Plus, I STILL got a lot of marks on the plastic base, that I cannot get rid of - and some of them are visible against light too.

So, to those of you who do this with success, how is it you run 12 negatives at once with NO issues?

[Bob Salomon]

Some users doing black and white back to back put a piece of plastic widow screen between the sheets to prevent contact. Others pre soak the film quickly in a water bath before sandwiching them back to back, some people do both.

[georg s]

My record is 360 negatives at once without issues:-) But I'm talking about 10 rolls of 135/36 - 5 pairs of Fuji 400 or 800 back-to-back in a Jobo Multitank 5. It was the only way to deliver some soccer-shots when approaching the dead-line. I wouldn't do this again - maybe for test-shots or so but without a doubt not with 120 or 4x5-negatives.
I could be wrong but I think some decades ago a bigger Combi-Plan tank was made - for 2x6 negatives.

[Wade D]

A pre-soak before putting the film back to back should wash off the blue-green anti-halation backing. For the film already processed try re-fixing then washing again. All might not be lost.

[Bob Salomon]

My record is 360 negatives at once without issues:-) But I'm talking about 10 rolls of 135/36 - 5 pairs of Fuji 400 or 800 back-to-back in a Jobo Multitank 5. It was the only way to deliver some soccer-shots when approaching the dead-line. I wouldn't do this again - maybe for test-shots or so but without a doubt not with 120 or 4x5-negatives.
I could be wrong but I think some decades ago a bigger Combi-Plan tank was made - for 2x6 negatives.

A 5x7 Combi Plan system was available up to the early 80s. It took up to 12 sheets of 45 but could not do inverse agitatation due to the weight of tHe chemistry but the L version did have a light-tight lid. You had to remove it in the dark to change chemistry. So it worked differently then the 45 Combi.

[ki6mf]

If you put a screen between sheets of film you need to do two things. Soak the screen in developer, stop and fix to remove any chemicals that are soluble to the chemicals. Second look at the spec sheet and make sure if you are diluting the mix to make sure there is enough developer adequately develop the sheet film. You could also buy additional HP Combis too.

[jp]

I run 2 combiplan tanks sometimes when I have a lot to process. Start the second one five minutes after the first, and it eats up the boringness of the development step.

[gevalia]

I won't do more than 6. In fact, I do 4 per unless I'm testing. I know I've never had a problem with 4. Occassionally with a batch of 6 I do so I''d never bother trying 12. I do what works 'consistently' for me.

[mortensen]

Thanks for the input, everybody... it seems to me that presoaking and developing/stopping/fixing the in-between-sheets-screen eats most of the time spared, since i can run a cycle in around 23 min including wash (foma in xtol is FAST). Another thing - I wouldn't dare sticking two presoaked sheets together in the dark and make them fit in the reels. Way too risky imo.

Btw. Bob, since you are the combi-plan oracle in here , how would presoaking etc. prevent the marks on the plastic base? Even with a screen in between, the film would still stick to the surface and have to teared off, right?... and that seemed to what caused the marks on the base.

I'll try refixing/washing, Wade - thanks for the tip.

[Bob Salomon]

Thanks for the input, everybody... it seems to me that presoaking and developing/stopping/fixing the in-between-sheets-screen eats most of the time spared, since i can run a cycle in around 23 min including wash (foma in xtol is FAST). Another thing - I wouldn't dare sticking two presoaked sheets together in the dark and make them fit in the reels. Way too risky imo.

Btw. Bob, since you are the combi-plan oracle in here , how would presoaking etc. prevent the marks on the plastic base? Even with a screen in between, the film would still stick to the surface and have to teared off, right?... and that seemed to what caused the marks on the base.

I'll try refixing/washing, Wade - thanks for the tip.

Presoaking prevents the film backs from sticking together. It really only needs a 20 or 30 second presoak. But just sandwiching dry sheets with widow screening also works.

How do you fill the tank and empty it? Through the Light Tight Hose Connectors or somehow else?