BW reversal: mix of negatives and positives on same roll

[pkr1979]

Hi all,

So Ive been developing Ferrania Orto in PQ 1+5 (with thiocyanate), dichromate bleach, clearing, iron out and fixing (washing between steps). Today I tried swapping the PQ with MCC at 1+2 (with thiocyanate) and ended with a weird mix of positive and negative images. I did check the roll after the clearing and it looked fine to my eye, so I doubt its the bleach. There is a chance I mixed the Iron Out in regular tap water instead of distilled battery water. So Im thinking its either that or the MCC. But as everything seemed fine after clearing the chance of the problem being the MCC also seems less likely.

Anyone got any ideas?

Cheers
Peter

 

[pkr1979]

I could also mention that there are more negatives at the center, and positives at the outer part of the reel (Paterson). I mixed the Iron Out in the water just before use (I still cant say if it is tap water or not).

 

[koraks]

Any chance of seeing some examples?

Partial negative suggests the bleach didn't go to completion. Did you use fresh dichromate bleach? Note that an acidified dichromate bleach isn't stable; it'll last up to a couple of days, but it'll die gradually.

 

[pkr1979]

Fresh dicromate bleach. Same recipe as always. Never had any problems. Examples may come.

 

[Donald Qualls]

Bad Iron Out wouldn't cause negative frames, it would cause thin positives, assuming the bleach step worked. But if the bleach didn't work, you should have gotten fully black frames, or positive with a very high Dmin (if you used light exposure reversal, you'd get Sabbatier effect). What it is I'm not sure, but I'm pretty confident what it's not.

 

[pkr1979]

Some of them might be a bit Sabbatier effect-like (they are stil hanging to dry). They are not reesxposed by light though - as you probably already knew - as I was using IronOut.

 

[pkr1979]

Is there any chance its caused by the first developer?

 

[Donald Qualls]

Not unless there was undeveloped halide in places that were supposed to be clear -- and even then, fully fog/developing the halide should have led to either full black or high Dmin positive images.

Now, a silver image negative or positive can appear to reverse with the right combination of front lighting and a black background -- like viewing an ambrotype mounted on black velvet, for instance. You might find, once fully dry, that the "negative" frames are actually normal positives like the rest of the film...

 

[relistan]

To me, it seems most likely to be a combination of two failures:

1. Incomplete bleaching
2. Either the first developer was partly exhausted, or the Iron Out was not mixed or circulated in the tank well enough

Both could also indicate that it was not spooled properly, but presumably you unspooled it so I assume that was not the case.

 

[pkr1979]

Im not sure how helpful these mobile scans are but they should help some. The first one is of a piano, and the beginning and the ende of the film. The next are to frames next to each other on the roll, one negative and the other 'positive'. I think its strange that two so close frames are so different. The last one is kind of a positives I guess.

I cant understand that this is the bleach as Ive been using the same stuff mixed up the same way for ages. Any clues?

 

[loccdor]

Looks like the Sabbatier effect I was getting on a C-41 reversal process of Aerocolor I recently tried... I notice your underexposed image of the kid is negative while your picture of him with more exposure is positive - that is the threshold effect I was seeing as well, although I saw it in reverse, with the brightest parts of my image turning negative. However I don't know why it's happening here.

 

[koraks]

I'm not sure either what's going on here; a couple of possibilities come to mind which would have to be eliminated one by one:
1: Failure of the fogging exposure (chemical in nature in this case). This can be verified by using an optical fogging exposure instead and see if that helps.
2: Failure of the bleach, although I'd frankly not expect this to be the root cause
3: Failure of the fogged silver halides to successfully develop in the reversal developer for whatever reason.

It's been suggested before in similar instances, although permanganate instead of dichromate bleach, by @Alessandro Serrao that metabisulfite is required in the bleach clearing bath (e.g. here: https://www.photrio.com/forum/threa...-process-with-photo-paper.213019/post-2886497) IDK, might be worth a shot in case #3 turns out to be part of the problem. I couldn't say, really; I use dichromate bleach in a different application (intensification) and given sufficient re-exposure, all silver always successfully redevelops.

 

[pkr1979]

Ive been using sulfite for clearing for a long time without any problems. It is also my impression that most people using dichromate use that without any issues.

 

[dokko]

I used dichromate bleach after sulfite clearing bath for many years for reversal super8 processing (as per the old Kodak instructions), never had any issues and the bleach was stable for weeks (if not months).

now I'm using permanganate bleach with sulfite clear (per the modern Kodak instructions) and have to be much more precise in the procedure not to get solarisation issues.

 

[pkr1979]

To me, it seems most likely to be a combination of two failures:

1. Incomplete bleaching
2. Either the first developer was partly exhausted, or the Iron Out was not mixed or circulated in the tank well enough

Both could also indicate that it was not spooled properly, but presumably you unspooled it so I assume that was not the case.

I'm not sure either what's going on here; a couple of possibilities come to mind which would have to be eliminated one by one:
1: Failure of the fogging exposure (chemical in nature in this case). This can be verified by using an optical fogging exposure instead and see if that helps.
2: Failure of the bleach, although I'd frankly not expect this to be the root cause
3: Failure of the fogged silver halides to successfully develop in the reversal developer for whatever reason.

As the only thing that I know I have changed is the first developer (Ive done this exactly the same way a lot of times with PQ) I suspect that change is at fault. Or that Ive used wrong water with the Iron Out.

The first developer was not exhausted when poured, and I assume developing one film for 14 minutes will not exhaust it either. But is there any way the first developer, even if its nothing wrong with it, can cause failure of the fogged silver halides to develop in the reversal developer?

 

[koraks]

Or that Ive used wrong water with the Iron Out.

I wouldn't waste time looking into that direction. It's not a significant factor.

is there any way the first developer, even if its nothing wrong with it, can cause failure of the fogged silver halides to develop in the reversal developer?

I don't see how.

 

[Raghu Kuvempunagar]

I've had similar results with Kodak Double X when the dichromate bleach was nearly exhausted and agitation was not adequate in the bleaching phase.

 

[pkr1979]

Dichromate bleach was fresh. Agitation as always. Im not sure how scientific this is, but I just took a developed and fixed negative ledger of a film and dropped in the bleach and it cleared within seconds.

 

[dokko]

from the three phone examples you posted, a few things come to mind:

- even in the frames which came out as positive, the sprocket area and the in between frames are clearly not fully developed. this could mean:
a) the fogging/re-exposure step was not working properly
b) the second developer was exhausted
c) something (bleach/clear/re-exposure/fogging) desensitised the emulsion (very unlikely in in this degree)

- there seem to be blotchy spots in the perf area.
the only thing that I can imagine causing this would be the fogging step.

- now for the really strange part:
in the second example with one negative and one positive image, the negative frame is no truly negative. if you look closely, the left side of the head band is negative, while the right ride is positive.
similarly, in the positive image the right ear and the scarf is negative

this means in any case the first developer was working, but
in the case of the negative, the bleach and the fogging and/or the 2nd dev was failing in certain spots.

add the fact that there's a mix of positive and negative in a single frame, and personally I'd discard all the chemicals and start fresh. I'd also do a re-exposure to light rather using a fogging agent, but that might be just bias due to old habits.


so it must be a multi facetted problem. if the bleach was working properly, there wouldn't be any negative left anywhere, and if the fogging/2nd dev was working properly, the sprocket area would be black.

 

[pkr1979]

Im not sure how relevant this is, but when examining the film after the clearing step the negatives was much more faint (as expected) than the negatives after the process was completed.

 

[Raghu Kuvempunagar]

If the bleach indeed worked perfectly, i.e. it removed the metallic negative image after first development completely, none of the subsequent steps can reverse the tone. For tone reversal to happen, some of the silver developed by FD needs to be available as halide for the second development. This can happen when the dichromate bleach has small amounts of Chloride impurity resulting in rehalogenation especially in the heavily exposed areas of the negative.

 

[pkr1979]

If the bleach indeed worked perfectly, i.e. it removed the metallic negative image after first development completely, none of the subsequent steps can reverse the tone. For tone reversal to happen, some of the silver developed by FD needs to be available as halide for the second development. This can happen when the dichromate bleach has small amounts of Chloride impurity resulting in rehalogenation especially in the heavily exposed areas of the negative.

Im not sure I get this - do you mean that tone reversal (which Im not sure what is) has happened here?

 

[Raghu Kuvempunagar]

These regions should have been darker in the positive but they are very light as they would be in the negative.

 

[pkr1979]

View attachment 397191


These regions should have been darker in the positive but they are very light as they would be in the negative.

And this indicates that what has gone wrong?

 

[koraks]

Your bleach didn't work as it should.