Chromium intensifier use on B/W reversal?

[Supercine]

Hi,
I’ve shot 2 (very) expired rolls of Svema black & white super 8 film. Both with the same camera shot within a week or so of each other. Both developed (first dev) for 8 minutes at the same time. And one is much lighter than the other. I know that both films may have not been stored the same and this may have influenced the outcome; however!

My question is can I use chromium intensifier on black and white reversal?

 

[koraks]

Yes, it doesn't matter where the silver image came from. It should work just fine. You can use dichromate or permanganate; the former is faster and more robust, but the latter is safer and also works.

 

[Supercine]

Thank you @koraks !
Can I use the reversal dichromate bleach that’s made with sulphuric acid, or does it have to be a specific hydrochloric acid bleach?

 

[koraks]

For an intensifier, there needs to be rehalogenation taking place, which requires (guess what) a halogen. That's why hydrochloric acid is commonly used - it acidifies and adds chloride. I expect you could achieve the same thing by adding sodium chloride to your sulphuric acid bleach. However, that can then no longer be used as a reversal bleach anymore!

For reversal, use the sulphuric acid version.
For intensification, use the hydrochloric acid.

 

[Supercine]

That makes sense! I’ll make a new bath with HCL.

 

[koraks]

Good luck!
I usually make only what I need for one session, then reduce to Cr(III) when I'm done using bisulfite and discard.

 

[Raghu Kuvempunagar]

For application in reversal processing, Chromium intensifier is most useful when the slide is of low contrast but has clear highlights. If the highlights in the slide are not clear, Chromium intensifier will add density to the highlights as well making them even more dark.

 

[koraks]

That's a good point @Raghu Kuvempunagar
The result may be disappointing on these slides. Maybe it's best to bleach them first - although that will also leave less shadow density for the intensifier to work on later on.