View Full Version : B&W Reversal Processing
04-02-2014, 05:02 PM
I hope someone can guide me in the right direction on this. I am no chemist. I'm getting nice results, but I have an overall brown tan to my highlights. Not getting any whites. Is this possibly a result of over-development in the 1st developer? Result of a bit of hypo in the developer?
It doesn't appear until the second development. Is this due to my bleach? The purple stain of my bleach does magically vanish in my clearing solution.
Here are my details:
Ilford MGIV RC B&W photo enlarging paper rated at ISO 3
1)Developer Kodak Dektol stock with 3ml of hypo solution for 2:00 minutes
3)Bleach for about a minute
5)Clearing solution for about a minute.
7)Second exposure was done in daylight at sink while clearing and rinsing for only a couple minutes at most.
8)Second developer 15 seconds by inspection
10)Fix (fixer of your choice)
Bleach (2 part stock 1:1 makes very short shelf working. I get several days before it turns from purple to clear):
Part A: 2g Potassium Permangnate to 1000ml water
Part B: 28g Sodium Bisulfate to 1000ml water
30g Sodium Metabisulfite to 1000ml water
Hypo Stock Solution:
32g Sodium Thiosulphate pentahydrate (Hypo) to 1000ml water
04-02-2014, 10:51 PM
Hello Wayne: I've only reversed film but I think that, regardless whether part "A" is Dichromate or Permanganate, part "B" should be Concentrated Sulfuric Acid instead of Sodium Bisulfate. Just curious the paper is being exposed in a camera and not under an enlarger? You also might use the Google custom search feature at the top right of this page and try searching for B&W paper reversal formulas and see what that shows.
04-02-2014, 11:20 PM
Yes. I am exposing these in camera.
I brought these recipes over from film reversal. I did see several different recipes for the bleach and went with the bisulfate bleach. Bleaches great, and the visible stain clears up in the clearing agent.
I suppose I could mix up some sulfuric and try.
04-07-2014, 04:37 PM
Haven't been able to find any acid here locally. Quite a surprise. Heh. Have to find it in the city next time I go.
But I did some more experimenting and dropped first developer time and found when I drop down to 1 minute, it's looking white.
04-07-2014, 10:56 PM
Here I have taken the 1st development to 1 minute, and the 2nd development to 20 - 30 seconds. It was taken to completion.
04-10-2014, 10:54 PM
Hello Wayne: That looks better. I guess I was trying to apply my experience with film reversal to paper. Given this result, reducing the developers times could solve the problem. I have a question regarding this process. Since you are using Multi Grade paper would you be able to alter the contrast by placing variable contrast printing filters in front of the lens to change the contrast of the final image?
04-10-2014, 11:26 PM
Could you please clarify step 7. Expose to light in daylight?
04-11-2014, 09:49 AM
Contrast filters should work fine. Though you do have to take into account exposure compensation. Which is simple enough. I think published data out there for the filters themselves should tell you exactly by how much to avoid having to experiment much.
I actually have thoughts to experiment with split grade multiple exposures. Am I crazy? Heh.
04-11-2014, 09:53 AM
"Could you please clarify step 7. Expose to light in daylight?"
Well, generally you would use artificial. Hold it up to a light source re-exposing the front and back for a minute or two. But I'm usually working at my kitchen sink during the day.
Doing this reversal with film, causes solarization if exposed to direct sunlight. So to be safe (because I never tried direct sunlight), I have avoided direct exposure to the sun. Overcast seems to work good. And keeping in the tank, and below to edge of the sink, or in the white plastic pitcher during clearing seems to work good for me.
I just don't allow direct sunlight to fall on it. Staying in normal daylight in the diffused ambient light around me works great.
04-11-2014, 10:06 AM
Like film, I'm guessing some papers would work better than others. I just reverse film, so I can only give a bit from experience there.
1) Contrast. Develop more in the 1st to get better contrast. It looks like it is ok with the images shown.
2) Add more hypo in the 1st if you are not seeing enough detail in the highlights. Testing with overcast skies may not be a good thing.
3) Blacks come from the flash and 2nd devlop. Stronger developer helps.
04-11-2014, 11:52 AM
You can turn the lights on, from the moment the print hits the bleach. It is acidic enough to prevent any more developing. You may then see when enough bleaching has been done. After enough runs, you can tell when the development has been correct too.
Gerald C Koch
04-11-2014, 12:33 PM
Hello Wayne: I've only reversed film but I think that, regardless whether part "A" is Dichromate or Permanganate, part "B" should be Concentrated Sulfuric Acid instead of Sodium Bisulfate.
There is no chemical reason not to use sodium bisulfate (sodium hydrogen sulfate). It is a safer alternative to concentrated sulfuric acid. Either bisulfate or dilute sulfuric acid are capable of providing a low pH for the bleach.
Sulfuric acid can be purchased in dilute solution 10% to 51% as battery electrolyte. Any store that sells batteries should have it. The percentage of sulfuric acid should be given on the label.
The secret to BW reversal processing is to judiciously follow a method that is known to produce good results. Another tip is that everything thing works backward. If your slides are too light then you must decrease camera exposure.