PDA

View Full Version : B&W Reversal Processing



Pages : [1] 2

WayneStevenson
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
2)Rinse
3)Bleach for about a minute
4)Rinse
5)Clearing solution for about a minute.
6)Rinse
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
9)Rinse
10)Fix (fixer of your choice)
11)Rinse
12)Dry.

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

Clearing:
30g Sodium Metabisulfite to 1000ml water

Hypo Stock Solution:
32g Sodium Thiosulphate pentahydrate (Hypo) to 1000ml water

spoolman
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.

Doug:)

WayneStevenson
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.

WayneStevenson
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.

WayneStevenson
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.

85791

spoolman
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?

Doug:)

SMBooth
04-10-2014, 11:26 PM
Could you please clarify step 7. Expose to light in daylight?
Thanks

WayneStevenson
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.

WayneStevenson
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.

mrred
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.

mrred
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.

tezzasmall
02-20-2015, 11:05 AM
I actually prefer the tones of the first picture = it's gives you something different from the norm that you seem to be aiming for ie white hightlights. Each to their own I suppose. :)

Terry S

MrBrowning
02-20-2015, 11:25 AM
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

I saw this thread pop up with a new post today and started reading it and I have a question. I've been thinking about doing paper reversal so I figured I'd ask. The above quote recommends mixing Potassium Permangnate and Concentrated Sulfuric Acid which I was under the impression is something that would be a bad idea (and I haven't seen it suggested elsewhere).

Taken from Wikipedia (which I know isn't the best source of information):

"As an oxidizer that generates the dark brown product MnO2 (http://en.wikipedia.org/wiki/Manganese(IV)_oxide), potassium permanganate rapidly stains virtually any organic material such as skin, paper, and clothing. Solid KMnO4 is a strong oxidizer, thus should be kept separated from oxidizable substances. Reaction with concentrated sulfuric acid produces the highly explosive manganese(VII) oxide (http://en.wikipedia.org/wiki/Manganese(VII)_oxide) (Mn2O7). When solid KMnO4 mixed with pure glycerol (http://en.wikipedia.org/wiki/Glycerol) or other simple alcohols (http://en.wikipedia.org/wiki/Alcohols) will result in a violent combustion reaction."

is this a moot point since you're diluting each part with a liter of water or is it still something what shouldn't be done?

Wiki Link http://en.wikipedia.org/wiki/Potassium_permanganate#Safety_and_handling

mrred
02-20-2015, 01:20 PM
Well it is a bleach and that's what bleaches do.......mask, glasses and gloves are in order. Mixing is probable where most care should be taken. The acid get's reduced to %2 / vol and I use 12g dichromate / l. I'm not sure of the permanganate would be any different.

As far as staining is concerned, some films do and some do not. I guess it would depend on what the base is made of. I'm guessing RC would fair better than rag.....but you may enjoy the look. In the past I have selenium toned (archival) the film which didn't hurt the look of the film (my opinion).

MrBrowning
02-20-2015, 01:27 PM
Well it is a bleach and that's what bleaches do.......mask, glasses and gloves are in order. Mixing is probable where most care should be taken. The acid get's reduced to %2 / vol and I use 12g dichromate / l. I'm not sure of the permanganate would be any different.

As far as staining is concerned, some films do and some do not. I guess it would depend on what the base is made of. I'm guessing RC would fair better than rag.....but you may enjoy the look. In the past I have selenium toned (archival) the film which didn't hurt the look of the film (my opinion).

Thanks for the response. I wasn't referring to the staining but the part of the quote that says: "Reaction with concentrated sulfuric acid produces the highly explosive manganese oxide ". I was just wondering if mixing even diluted Sulfuric Acid w/ the Permanganate would be a potential problem as this is the only time I've seen the mixture suggested regarding paper reversal.

pdeeh
02-20-2015, 01:47 PM
Your caution is to be commended because many of these chemicals are potentially dangerous.

However - combining dilute Sulfuric acid with Potassium permanganate solution to make silver bleach has been known for a very long time indeed.

I've done a decent amount of reversal testing using permanganate bleach, and I haven't managed to blow anything up yet, and I've never seen any reference to there being a problem with it forming explosive compounds - even here at APUG where there are plenty of proper chemists who would have advised special caution if there were any needed.

Permanganate bleaches are preferred by some as permanganate is much less toxic than Potassium dichromate, which is pretty vicious stuff.

Nevertheless like all photographic chemistry, you need to understand what precautions you ought to take.

FWIW, I understand that for paper reversal, a dichromate bleach is preferred as it is much less likely to stain. It has the other advantage of being quite stable (permanganate bleaches need to be mixed immediately before use, have only a very short working life once mixed, and are discarded after use, while dichromate bleaches can be reused)

mrred
02-20-2015, 01:50 PM
Normally you would dilute the acid first. So I keep a 2 litre bottle of %2 and work with that. My guess you would need much much stronger acid to start a reaction of any consequence. The sulphuric acid I bought was %20 to start with. It's strong enough to need to be treated with respect but about half the strength that would be in your car battery. But there are better sources of that information here and I predominately use potassium dichromate. I do not know of any apug users that had their darkroom explode.

Perhaps PE can ring in on this.

MrBrowning
02-20-2015, 02:00 PM
This is new territory for me and even though I've read on it here and on other sites I figured it wise to ask.

Thank you both very much for the clarification.

mrred
02-20-2015, 02:06 PM
You should definitely report back, successful or otherwise. I'm sure there would be a bit of interest on this.