BW reversal: mix of negatives and positives on same roll

[Alessandro Serrao]

So why does the bleach work with Dektol then? Ive kept all parameters the same - except the developer.

Because not all developers work the same. There are surface developers, there are developers that work more deeply...
I'd suggest to have a look at the excellent two volumes Grant Haist book, "Modern Photographic Processing". There's an excellent chapter dedicated to reversal.

 

[Raghu Kuvempunagar]

FD can't have an effect that is hidden throughout and surfaces only during second development. If FD did anything abnormal, it would have been visible to OP after bleaching/clearing. But IIRC OP said he checked and found the roll to be fine after the clearing step.

Nevertheless, it is best to check with @ADOX Fotoimpex about the compatibility of Adox MCC developer with reversal first development.

 

[Donald Qualls]

Someone pointed out that chloride ion in the bleach could cause something like this. Could bromide carried over from first dev into the bleach do it? I don't know what's in MCC, but some print developers include a significant amount of potassium bromide as a restrainer.

 

[Alessandro Serrao]

FD can't have an effect that is hidden throughout and surfaces only during second development. If FD did anything abnormal, it would have been visible to OP after bleaching/clearing. But IIRC OP said he checked and found the roll to be fine after the clearing step.

Nevertheless, it is best to check with @ADOX Fotoimpex about the compatibility of Adox MCC developer with reversal first development.

I agree.
This is the official msds for Adox MCC https://www.adox.de/MSDS/MSDS_MCC_DEVELOPER.pdf

 

[Alessandro Serrao]

Someone pointed out that chloride ion in the bleach could cause something like this. Could bromide carried over from first dev into the bleach do it? I don't know what's in MCC, but some print developers include a significant amount of potassium bromide as a restrainer.

I would exclude it, since for instance Kodak d19 has potassium bromide and a lot of it (5gr/lt) and there's a long wash after the FD step...

 

[pkr1979]

@Raghu Kuvempunagar , I did check after clearing. There is a chance I should have checked better, but my impression was that everything was ok.

@Alessandro Serrao , its unclear to me what you mean is wrong with the bleach. I havent read the Unblinking Eye article yet, but after having a look its my impression that the issue is related to permanganate bleach only.

I also wonder why the bleach is to blame when it works fine with Dektol and PQ. Does that mean that its strong enough for those developers, but to weak for MCC?

 

[Alessandro Serrao]

@Raghu Kuvempunagar , I did check after clearing. There is a chance I should have checked better, but my impression was that everything was ok.

@Alessandro Serrao , its unclear to me what you mean is wrong with the bleach. I havent read the Unblinking Eye article yet, but after having a look its my impression that the issue is related to permanganate bleach only.

I also wonder why the bleach is to blame when it works fine with Dektol and PQ. Does that mean that its strong enough for those developers, but to weak for MCC?

The problem is the bleach, not the developer. What you've read in the Unblinkingeye page is about permanganate bleach but dichromate bleach works the same.
Not all developers are created equal, hence what you see it's incomplete bleaching or bleaching contamination by some kind of halides (Cl, Br, I) along with maybe insufficient clearing or an exhausted clearing bath.
Make a fresh new bleach batch and retry with Adox MCC 1+4 (1+1 is overkill), with some thiocyanate in it, not exceeding 12min developing time, otherwise you'll start losing DMax.

 

[koraks]

What you've read in the Unblinkingeye page is about permanganate bleach but dichromate bleach works the same.

There are very distinct differences in practice between permanganate and dichromate bleach. The latter is far more robust, generally faster and overall less prone to problems.

 

[dokko]

I don't really see how a failed 1st dev or bleach would explain a transparent perforation area.

 

[pkr1979]

The problem is the bleach, not the developer.

This depends though - doesnt it? When the exact same bleach works just fine with Dektol and PQ (even after failing with MCC twice).

Make a fresh new bleach batch and retry with Adox MCC 1+4 (1+1 is overkill), with some thiocyanate in it, not exceeding 12min developing time, otherwise you'll start losing DMax.

I would expect this to be too weak considering PQ is mixed 1+5 instead of 1+9, and Dektol 1+1 instead of 1+2. Both for 14 minutes with thiocyanate (2.5g/L).

I don't really see how a failed 1st dev or bleach would explain a transparent perforation area.

Me neither - but keep in mind that everything has been exactly the same except the developer (even the same working solution of bleach).

I can reproduce the failed results, and I can reproduce the successful results - by changing FD.

Also - Ive sent an e-mail to Fotoimpex to ask about MCC - I assume they will get back to me.

 

[pkr1979]

PS This is my bleach working solution:
100 ml 10 % dichromat solution
25 ml 50 % sulfuric acid
875 ml water (distilled)

 

[Alessandro Serrao]

I don't really see how a failed 1st dev or bleach would explain a transparent perforation area.

I've not spoken about a failed fd or bleach, but incomplete fd or bleaching action.
And no, on the first and third strip the sprocket hole area is everything but transparent...

 

[koraks]

PS This is my bleach working solution:
100 ml 10 % dichromat solution
25 ml 50 % sulfuric acid
875 ml water (distilled)

That will bleach anything pretty much instantly. The bleach would still be quite effective at 10x this dilution - it just takes a bit longer; a few minutes at the 10x dilution. At your dilution, it should get the job done in 10-15 seconds flat.

 

[lamerko]

This is the standard Kodak bleach - there shouldn't be any problems.

 

[Alessandro Serrao]

This is the standard Kodak bleach - there shouldn't be any problems.

but the bleach can be exhausted

 

[koraks]

but the bleach can be exhausted

It cleared a fully developed, dense leader in seconds. It's evidently not exhausted.
All questions and suggestions you've been bringing up were addressed on the first page of this thread. Please take a moment to read what was already discussed back then.

 

[Alessandro Serrao]

On the first strip image, at the bottom the film leader it's supposed to be jet black while it's transparent...
Also the other snippets: the sprocket holes area should be jet black while it's mostly transparent...

 

[Alessandro Serrao]

It cleared a fully developed, dense leader in seconds. It's evidently not exhausted.
All questions and suggestions you've been bringing up were addressed on the first page of this thread. Please take a moment to read what was already discussed back then.

It's not addressed, with all limitation that can imply a forum discussion, first of all.
I'd ask the OP to post the scan of the film leader to see if it's black or not for example...
I'd also proceed as following:
1) take a film strip and use Adox Mcc to develop as negative, then stop, the fix and see what's coming out: the sprocket holes area should be transparent;
2) take a strip exposed only to light and then process it as reversal: it should come perfectly crystal clear with a slightly light veil;
3) take a non exposted film strip and process as reversal: the sprocket holes area should be jet black...
I'd ask the OP to measure the bleach pH...

 

[lamerko]

I don't know exactly how the stripping process works, but I assume that eventually the buildup of silver sulfate will deplete the sulfate ions.

 

[koraks]

I don't really see how a failed 1st dev or bleach would explain a transparent perforation area.

Yup. For that reason I'd suggest to do another A/B test with the MCC developer and Dektol, but this time use optical fogging instead of chemical fogging. The image-wise evidence points in the direction of failure of the fogging step.

 

[pkr1979]

The bleach was not exhausted. I might test more, but Im hoping for some sort of reply from Adox first. If I get one I'll let you know what they said.

 

[koraks]

I don't know exactly how the stripping process works, but I assume that eventually the buildup of silver sulfate will deplete the sulfate ions.

Depletion of sulfate isn't really what's likely to happen. Basically, the dichromate steals electrons from the silver, and the resulting silver sulfate is somewhat soluble, so the silver ions lave the emulsion and end up in the bleach. There, what matters ultimately is the electron balance and that remains unaffected since the electrons donated by the silver end up in the dichromate (turning hexavelent chromium into trivalent). What can happen is either of two things: the dichromate runs out, or the solubility limit of silver sulfate is reached. You could run the numbers on which will happen first. The former is evidenced by a color change in the bleach, which will turn a less saturated ochre and ultimately somewhat greenish, at which point it'll be insufferably slow already. In either case, the bleach would become ineffective, which is at odds with @pkr1979's observation of the bleach readily clearing a dense test strip.

 

[lamerko]

Hmm... I was under the impression that this amount of dichromate was large enough for it not to happen...

 

[koraks]

As said, theres no indication here of the bleach running out of steam.

 

[lamerko]

As said, theres no indication here of the bleach running out of steam.

Yes, I am convinced of that too.