Permanganate-based b&w reversal simply isn't quality reversal
It's more a statement than a question: after two full days of experimentation, I come to the conclusion that using a permanganate-based bleach for b&w reversal simply doesn't give a high quality slide, for what are my quality standards.
Am I too picky, am I not?
Comments are welcome. I will revert back to b&w negatives. Thanks for all the helpful replies on my last post, which was related to my b&w reversal experimentation.
Alessandro - are you using a kit or mixing it from scratch? What was the quality issue you ran into? I was considering it for internegative work, but have not done any experimentation. The kind of vague instructions about exposing to light as part of the process makes me wonder if there are just too many variables to get a consistant result. Is their anyone who has had sucess?
Basically the quality issue I'm running through is that there's a good probability that the emulsion can come off the film base due to the high pH changes involved in the process.
Originally Posted by Dug
Or the emulsion can remain irrimediably reticulated, the light exposure add another variable to the process ecc...
Black and white negatives are not intended to be reversed, there are other type of films intended for the use.
Let's use what is made for: Scala, Foma 100R.
I'm tired to ruin rolls after rolls just because the process has too many variables to count.
Forget the consistant results: have a Scala roll processed by a Scala authorized lab, that would be the best bet.
As I said I'll revert back to the ol' b&w negatives, to what's is intended for.
you may check http://www.galerie-photo.com/inversi...oir-blanc.html . for sure the article is in french but you will see that Claude get low B+fog. He use to add sulfocyanure in the first developper and to rinse between each step.
Personally I use the dichromate method beacause of I got a lot of bichromate at home , but I already try the permangante and the ceriu mehod and all three give good result.
What exactly do you mean by good results?
Originally Posted by nze
I've got too much emusion softening so that the image is not good.
Maybe I can give it a try once again.
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By good result I mean that I do platinuum and carbon printing with the negative I get from; But you want direct positive and in is about the same.
Some fim need to be harden after the bleaching , if not you will get problem with them. I usggest you to use a developper with sulfocyanure in it, rinse, bleach, rinse , harden and then expose to light and redevelop. If you ned help with the french article I may translate it. It ggive good information about the film to use. For example Efke film seems to give better result with the lower B+fog but need to be harden to avoid any trouble.
SO I change My words and write that you can get stunning result with this method.
Curious as Ilford recommends a permanganate bleach for reversal of their B&W films.
Originally Posted by Alessandro Serrao
I have always used a dichromate bleach for both B&W and color films and found it to be very dependable. There may be some pressure to use permanganate rather than dichromate since the later is more dangerous.
What kind of hardener do you suggest me to use?
Originally Posted by nze
I have only the potassium alum based hardener.
Can it be used alone (ie not in a fixer)?
I haven't neither the sulfocyanure buy only hypo: is that the same?
Alessandro, you posted this on photo.net and USENET as well, but nowhere do we see what process you are using. What is your first dev made of? How are you formulating your bleach? What are your temperatures and times? B&W reversal has a lot of variables, if you are trying to "invent" a new process you need to be very patient.
Yes, I posted it on USENET and photo.net. On USENET there's my complete recipe ("B&w proper reversal formula") but for convenience's sake I will repost it here:
Originally Posted by Jordan
I'm getting into developing my own b&w reversal film (now it's only
I've tried to set up a complete formula from various sources on the net and I've came up with something like this:
1) Kodak D-19 with sodium thiosufate added at 16g/l for 8 minutes, standard Kodak agitation
2) Pre-bleach bath: Tetenal hardener alone @ 25ml/l for 5 minutes
4) Bleach: potassium permanganate 4g/l (part A) and sodium bisulfate
34g/l (partB). Mix 1:1 just before use, for 2 mintes
6) Clearing: potassium metabisulfite 30g/l, for 2 minutes
8) Pre-exposure: Photo-flo for 30 seconds
10) Re-exposure: by means of a tungsten lamp 150w from a distance about 1mt for 2+2 minutes (2+2 refers to both faces of reel)
11) Second development: Kodak D-19 for 6 minutes
13) Fix: a fixer bath consisting of 120g sodium thiosulfate, 10g
sodium sulfite, 30g sodium metabisultite. To this I've added the Tetenal
hardener @ 25ml/l: the solution gets cloudy but fixes nevertheless...
15) Wetting agent
16) Hang to dry
Every step is carefully mantained to 20°C +-1°C by means of water baths
I got the following results:
- on T-Max 100 exposed at 100 I get very dark slides (dunno if they are underexposed or underdeveloped)
- the emulsion side of the film gets non uniform: it gets as something
has softened it too much.
What I'm doing wrong?
Precedently with Ilford films I got the emulsion off the base in my