Black and White reversal processing first developer

ruilourosa said:

Another thing... since sodium bisulfate is used in tropical developers and fixers as a mechanism to avoid excessive swelling, mixing a less toxic bleach based on potassium permanganate and sodium bisulfate as a substitute for sulfuric acid, would i end up with a less swelling bleach process and in that way preserve my gelatin a bit?

THanks

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You have things mixed up a bit. Sodium sulfate is used in tropical developers at 40 to 60 g/l. The small amount of sodium bisulfate used in a permanganate bleach is not enough to prevent swelling. Emulsion swelling and emulsion softening are two different things. It is the permanganate ion that causes softening of the emulsion. Copper sulfate based bleaches have the same fault.

Sodium bisulfate can be though of as a solid form of sulfuric acid. In this salt the sulfuric acid has been half neutralized.

The high pH of the Rodinal developer is not helping with the softening problem. It really is a poor choice for reversal processing.

Hello and thanks!! Well, i have been trying things... I used Rodinal 1+20 plus 10 gr per liter of thiosulfate, low Dmax, i did not like it, but my agitation was maybe under, i used regular ilford agitation... maybe that´s the cause for low dmax... or maybe the dilution is too low... I really liked to use rodinal as i can make it quite cheap... I will try more... The bleach: i used bicromate 10gr/ltr and sodium bisulfate 60 gr/ltr and it worked quite well i will try permanganate with bisulfate, maybe, just maybe the sulfate in solution prevents the excessive swelling and softening of the emulsion... and i manage to use the less toxic permanganate... let´s see.

Another thing: my images are brown... is it rodinal?



THanks


Rui Lourosa

Hummm! Why the bromide? none of the bleaches i saw had any!

Cheers

Thanks


Rui Lourosa

ruilourosa said:

Hummm! Why the bromide? none of the bleaches i saw had any!

Cheers

Thanks


Rui Lourosa

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R-10 is the bleach specified by Kodak for Tri-X Reversal 7266 film. This is the only remaining B&W reversal film made by Kodak.

http://motion.kodak.com/motion/uplo...Films/BW_Reversal/Technical_Data/H-1-7266.pdf

Hello


Gerald please, maybe it´s me that i´m wrong. The bromide is used in rehalogenating bleaches, but i think the bleached silver has no use for being sensitive then exposed and developed, otherwise the film would turn all black!
do you agree?


Thanks


Rui Lourosa

I don't recommend Rodinal for reversal processing due to its tendency to produce slight brownish tones. But in any case, take a look at this document, as it gives clear instructions for using it with several types of film. The author uses Potassium Thiocyanate instead of Hypo, for reasons well explained in the text:
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I followed its directions with Scala, Ilford FP4+ and HP5 and it works. It's superior to the Ilford method, but still not my cup of tea.

I recommend you to avoid any silver solvent in the first developer as much as possible, and using instead a really strong developer, long times and high temperature. But in the case you don't want to start mixing it from scratch, Tetenal Dokumol 1+9 works pretty well with many emulsions.
Also, a dichromate based bleach is far more reliable and effective than a permanganate one.

Good luck and be patient! Lots of experimenting awaits you!

ruilourosa said:

Yesterday i tryed developing with rodinal 1+10 +8 gr/liter of sodium thiosulfate in the first developer with the permanganate usual (ilford formula) bleach but the emulsion of the tmax 100 just fell apart... not sure if it was the bleach or the strong dilution of the developer. Tryed the second time but changed 2 variables: rodinal 1+20 +8gr/liter thiosulfate and dichromate bleach and it worked nicely (although i will give another minute in the development because the iso 100 was just a little bit dark) today i am going to test just one variable, i would prefer to have the permanganate bleach as it seems less toxic...

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It's the bleach permanganate is difficult to use without damaging the film.

Paul Verizzo said:

Could you amplify on why you say "better?" Especially since the Fomapan is designed for reversal.

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R100 isn't a great emulsion, sometimes has plenty of defects and odd results, even if 2 rolls of the same stuff in the same tank and one is fine. When it is fine, Delta 100 and T-Max 100 look better as slides.

There is no problem in mixing things from scratch but there is a preference for some immediacy conveyed by one shot long lasting developers, i will try a dektol, multigrade, universal type developer and more agitation... i want to make this a constant to start a job!


Thanks


Rui Lourosa