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Cross-Processing Color-Neg in b&w chemistry


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#1 Marc Roessler

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Posted 20 November 2010 - 07:48 PM

Hey all...

During the last few weeks I processed a few meters of 16mm color neg (7213 Vision3 200T, 7248 EXR 100T) in b&w chemistry and I wanted to share my experiences here.

I had some leftover Fomadon LQR so i used that one. The (already thinned) processing solution is about 3 weeks old now, still works good. The developer (in theory) should be consumed by now (1.8 liters, processed about 80 meters of film in it) but still seems to be usable for such experiments.
I rated the film normally (100T, 200T) and developed for 12 minutes. For the first batch I used a lomo tank, for following ones I just dumped the film directly into the tank (bucket-processing-style in a dark bathroom). The first neg batch seemed rater fat, so probably for fresh developer the right processing time is a bit less than 12 minutes.

After developing and fixing you will have an orange masked negative with a negative silver image. During the development step (and during the following washing) the rem jet will come off, which will kind of mess up your developer. However the developer can be re-used for future cross processing experiments. I've found it's best to bucket process in the dark, then wash in the dark while running the film through your fingers, this will remove the rem jet backing.

As far as I can tell by photographing the neg with my Ixus camera through a magnifier lens and inverting it digitally, it turned out nice. No way to upload images here, though - sorry.

Anyone else here played with this?
Color neg leftovers (especially recans shorter than 10 meters) are easy to get and are ideal for this. b&w developer is cheap as well, and 10 meters are easily "bucket processed".

Anyone tried to print such negs? I've read they are rather low-contrast (due to the color masking maybe?)...

Greetings,
Marc
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#2 Dominic Case

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Posted 20 November 2010 - 09:23 PM

Colour negative is lower contrast than black and white because it's made that way to extend the useful exposure range of the negative, and also to balance with the higher contrast colour print stock. Colour neg in its correct ECN2 process will give yo a gamma of around 0.50, whereas b/w is normally developed to around 0.65. You might get a little extra contrast in your b/w processed-colour neg with longer developing time, but probably not enough to make all that difference.

You also need to be careful with that remjet backing. As you say, it'll stuff up your developer solution, but also, any that gets on to the emulsion side of the film will be difficult - nay, impossible - to remove afterwards. When you get a good quality image from your neg you might find traces of very fine sparkle - that's the carbon remjet.

So I'd be cautious of re-using the developer for that reason.
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#3 Brian Pritchard

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Posted 21 November 2010 - 07:01 AM

You also need to be careful with that remjet backing. As you say, it'll stuff up your developer solution, but also, any that gets on to the emulsion side of the film will be difficult - nay, impossible - to remove afterwards.

I agree with Dominic's comments, however I would add that it is possible to remove backing from the emulsion. You have to carefully polish the emulsion with silver polish and then rewash the negative. It is very time comsuming and you have to take great care not to damage the film in any other way. I spent a morning earlier in the week doing exactly this. (not damaging neg but removing backing!) It is really only practical with occasional spots.
Brian
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#4 Marc Roessler

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Posted 21 November 2010 - 07:47 AM

Brian, at what step would this be done? I suppose after filming but before processing? I would like to try this, can you elaborate a bit?

Dominic, I supposed this would be a problem, as (afaik) usually extra care is taken in the lab that no parts of the rem jet get around the film onto the emulsion side when washing the rem ject off. Haven't really checked for it yet, as I haven't had a print or scan made yet and it's quite impossible to see with bare eye. I'm just toying around a bit though, so this is not a big issue for me at the moment... I mean, bucket processing.. this is really just for getting a feeling for the process and for fun at the moment.

Would you get a usable image (contrast wise) by carefully printing to color print stock using neutral printer lights? I'd have to expect color shifts I guess?

I will try to push a bit (2 stops), to see what happens to the gamma...

Greetings,
Marc
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#5 Brian Pritchard

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Posted 21 November 2010 - 10:05 AM

Marc
You do it after the film is processed. It is to remove spots of backing that has got onto the emulsion. You can use silver wadding cleaner (called Duraglit in the UK) or cotton wool with liquid silver cleaner. Afterwards you must rewash the film to remove the tiny abrasions you have made.
Backing left on the base side can be removed with cotton wool soaked in Perklone.

Brian
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#6 Patrick Neary

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Posted 21 November 2010 - 10:25 AM

Hi-

I do this every so often for quick slop tests, usually to check focus of an old lens or some other simple camera test. I've been souping the color neg clips in HC110 (dilution H) @68 for 9:30 and they form a decent, though grainy image that just needs a bit of contrast oomph in photoshop. The rem jet is horrible to deal with, it gets all over everything, and I don't make a huge effort to wipe it all off the film so it leaves interesting streaks and skid marks.
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#7 Dominic Case

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Posted 21 November 2010 - 04:18 PM

Wow, Brian. I havn't used silver polish (or Brasso) on a negative for decades! I'd almost forgotten about it. I was taught the technique, but there are very very few people I've actually dared to pass it on to. It's a powerful method - and was also useful for dealing with scratches before the days of wet gate printing. But it can go horribly wrong.

Thanks for the reminder of the trick.

Marc, yes, continuous processing machines used in labs have to have the remjet removal tank designed carefully. Sprays are directed at the base side of the film in such a way that no remjet-laden water finds its way round to the other side.

And yes, you would get a useable image if you printed with similar lights to what you'd print a normally processed neg with. Well - recognisable, not sure about useable.
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#8 Charles MacDonald

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Posted 21 November 2010 - 07:45 PM

And yes, you would get a useable image if you printed with similar lights to what you'd print a normally processed neg with. Well - recognisable, not sure about useable.


I assume that would mean printing on COLOUR stock. The Orange Mask would act as a good safelight for 2302/3302/5302/7302 or regular B&W paper for that matter.
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#9 Dominic Case

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Posted 21 November 2010 - 08:22 PM

I assume that would mean printing on COLOUR stock. The Orange Mask would act as a good safelight . . .

Yes of course, thanks for clarifying that, Charles. Sorry if my post was confusing.

In fact the orange mask wouldn't act as a safelight, otherwise it would be impossible ever to print to the magenta and cyan dye layers on colour stock. But in this instance, if you were printing onto blue-sensitive 5302 etc, you would need to increase exposure by about 2 stops (about 24 printer lights) compared with printing from a b/w negative. And the red & green printer lights would be irrelevant.
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#10 K Borowski

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Posted 21 November 2010 - 09:11 PM

If we *really* want to continue this intellectual exercise, we could always develop color PRINT stock as B&W too, or use another panchromatic sensitive B&W material.
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#11 Brian Pritchard

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Posted 22 November 2010 - 07:17 AM

I know of someone who regularly processes Agfa CP30 as black and white, I would have to check what gamma he gets but Agfa did some tests and made recommendations for processing through a normal B/W pos developer.
Brian.
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#12 Marc Roessler

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Posted 22 November 2010 - 01:57 PM

Intellectual? Not so much as I do intend to try this :)
For me it's a very interesting and highly educational thread. Thanks for all your contributions! I guess I will try to get hold of a few feet of 16mm color print stock for experimenting.
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#13 K Borowski

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Posted 22 November 2010 - 05:00 PM

Well, I assume you are going to develop color negative as a B&W, but after that, it's all a bunch of hypotheticals. I doubt you'd print onto blue-sensitive B&W stock, or photographic paper.

And I think it's silly (unless you've inherited a can of ECP film already), to try to cross process yet another stock when there are several B&W panchromatic materials you could just use instead.
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#14 Carl Looper

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Posted 22 November 2010 - 07:21 PM

it's all a bunch of hypotheticals.


Hypotheticals are very important because they provide a means for understanding what we would do if the world was different. Although this may assist our understanding of risk, and help us plan and create a new and better future, hypotheticals also help us understand the past, and why things happened or how things work.


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#15 Patrick Neary

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Posted 22 November 2010 - 10:58 PM

Yes you wouldn't want to actually have fun experimenting or just messing with stuff to see if anything interesting results.
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#16 Patrick Neary

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Posted 22 November 2010 - 11:02 PM

Marc, yes, continuous processing machines used in labs have to have the remjet removal tank designed carefully. Sprays are directed at the base side of the film in such a way that no remjet-laden water finds its way round to the other side.


Just out of random curiosity, what happens to all of that remjet sludge; just down the drain or is it managed differently?
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#17 K Borowski

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Posted 22 November 2010 - 11:32 PM

I've cross processed color film in B&W myself. While there are advantages to this (using stock that otherwise wouldn't be available in B&W neg), there is little or no advantage I can think of to using cross-processed color print stock too. If anything, you'll just spend more money for roughly the same result :unsure:


I don't know why you're implying I am against experimentation, Patrick. I've done plenty myself. I am not interested in seeing how many complicated, convoluted steps I can take to get from point A to point B though. Some people are after a certain result. Others are after the ability to brag about HOW they did something, that is often otherwise unremarkable.


As an aside, rem-jet removal is a PITA. I try to avoid it when possible. It's just carbon fiber, if I recall correctly. Nothing toxic about it, but I haven't had to dispose of it commercially, so there may be more to it than just hooking up a drain pipe at the bottom of a prebath tank.
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#18 Patrick Neary

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Posted 23 November 2010 - 12:18 AM

Just needling :)

But I'm a person who really enjoys messing with this organic stuff while it's still around to be messed with. Digital isn't nearly as satisfying in that way.
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#19 Dominic Case

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Posted 23 November 2010 - 12:24 AM

As Karl says, remjet is just carbon. But it doesn't necessarily go down the drain. Most wash water in the better film laboratories is recycled, so the carbon will be filtered or otherwise separated out. Then it joins company with other nastier sediments (the non-recyclable chemicals from the processing solutions) that are (at least where I used to work) then compressed and carted off for suitable disposal.
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#20 K Borowski

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Posted 23 November 2010 - 12:58 AM

Digital isn't nearly as satisfying in that way.


Who said anything about digital?


The whole point, at least to me, of doing something in an alternative process, is to obtain a result that cannot be obtained with a commercially standardized (read "easier" or "cheaper") process.

Are you saying that there is something to be gained from printing color print stock and cross processing in B&W chemistry over just using a panchro B&W stock? (Watch, someone is going to come on here and say ECP is cheaper). I would think that ECP wouldn't be able to obtain the D-max of a B&W stock designed for producing dense, black metallic silver, but could be wrong. If Agfa has recommended development times for CP-30 ECP stock, then maybe it is a good analog to regular panchro B&W stock, but that might not hold true for ECP stocks from Kodak and Fuji.

I've heard that color photographic paper is not optimal for B&W development, for example.



As far as rem-jet removal goes, I would imagine that the problem in getting rid of it would be physical, not environmental. It's a black sludge that could probably clog up a drain if you poured enough down it.

It's almost certainly a non-issue with a few hundred feet. Labs deal with millions of feet, so they have a problem the darkroom hobbyist doesn't.
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