I have a set of negatives that appear to be slightly over-exposed and over-developed. I'm considering treating them with a proprotional reducer. I have some potassium ferricyanide and hypo that I could use, but I noticed that Photographer's Formulary sells a potassium permanganate-ammonium persulfate reducer (Reducer III) that might be better suited to my purposes. My complaint with potassium ferricyanide is that it is difficult to control/predict. Anyone have experience with the potassium permanganate-ammonium persulfate reducer? I'd be interested in hearing if it has any advantages or drawbacks. BTW I have some test negs from the roll -- I understand the risks of reduction.

-- Chris Hargens (ldmr@cruzio.com), November 12, 2001

Answers

How slightly over exposed and slightly over developed are the negs. Bleaching or reducing negatives is chancy at best. And increases grain. Have you printed them yet? How do they look. Contrast can be tackled in a number of ways that I would try before reducing the negs. Try them first. Ferricyanide is not a proportional reducer and will bleach the shadows long before you see any effect on the highlights. James

-- james (james_mickelson@hotmail.com), November 12, 2001.

I used the word "slightly" because I believe that I could print these negatives almost acceptably with with a condenser enlarger and the appropriate contrast filter. However, I am now scanning my negatives, and they are bit too dense. I've tried extending the exposure which almost brings them to where I want them, but not quite. Anyway the PF reducer, Reducer III, sounds like something that might help. Do you have any experience with it?

-- Chris Hargens (ldmr@cruzio.com), November 12, 2001.

The only proper way of doing what you try to achieve is a two part process. This is also the professional way used by good custom labs. First you have to rehalogenize the negative which will enables you to redevelop. There are several receipes for bleaches that will achieve this, eg ORWO 710: potassium(II)-sulfate krist. 100g, sodium chloride 100g, sulfuric acid D20 25ml, add water to one liter. The bleach can be used for a very long time and has a very high capacity. Bleach out the complete image, which will be done in about 30secs to one minute depending on the temperature of the bleach. You will only see a faint yellow looking image. Redevelop in a negative devloper until you reach your desired density and then transfer to a stop-bath or plain water stop. You can doo this under light. Since the first development determined the acutance this will not change with the second development. What you will affect in the redevelopment is the grain size though. The classic formulations call for a super fine grain developer. The ORWO 710 recipe has a developer of 3g p-penylendiamhydrochloride and 20 g of sodium sulfite on one liter. Speed is no issue for redevelopment. I can highly recommend ORWO /Calbe A49 for redevelopment in 1:1 dilution or classic Rodinal R09 in 1:100 or 1:200 if you want to affect overal contrast. If you do not want to mix you own bleach then the bleach in sepia toner kits will do the same. Do not forget to wash between bleaching an redeveloping so that you do not have a carry over of bleach. This is a very safe process, since you can repeat it as often as you want as long as you do not fix in the end (which you have to to get permanent negs). This process will not only reduce but also intensify depending on the type of developer you are using. One part reducers are very hard to handle, since in the beginning not much seems to happen and then everything goes too quick. Also what you see is not always what you get, since the image often does change in the fix, which is the case with farmer's reducer.

-- Volker Schier (Volker.Schier@fen-net.de), November 13, 2001.

Thanks for the info & suggestion. It sounds like I could get similar results using a chromium intensifier to "bleach" the negative and then stopping the redevelopment process when the negative reaches the desired density. Perhaps I'll experiment a bit just to what results I get.

-- Chris Hargens (ldmr@cruzio.com), November 14, 2001.

Actually no, since you cannot change the gradation of the neg with your reducer and this may be what you want to achieve too. The reducer you are looking at is subtractive. Many of these are based on the combination of potassium permanganate in a sour enviroment, e.g. ammonia or concnetrated sulfuric acid. These family of reducers gets closest to what one can call an "overall" reduction (if one opts for a one part formula). You can formulate these reducers yourself for very little money: For example ORWO 708: Water 100ml, potassium permanganate 1g and concentrated sulfuric acid 5ml. For reducing use 4ml on 400ml water. The ammonia in the formula you are looking at is just to trigger the process and can be substituted by sulfuric acid, even a sufficient amount of battery acid. Subtraktive reducers definitly work more on shadows than on highlights. The stock keeps for a very long time, the diluted reducer for some days. The redeveloping process I wrote about gives you many more controls, since you can adjust a variety of parameters AND the overall results mostly are superior, since the grain will not get coarser through reduction, which will get obvious if you reduce longer with almost any one part reducer. I therefore would only recommend one part reducers for prints and in this case it often is easier to redo the print. I do not know which film format you are using, but for 35mm film grain this is a real consideration. Photographers generally keep away from one part reducers if it is important work, since the effects cannot be previsualized. With redevelopment and can experiment without the penalty of losing your neg.

-- Volker Schier (Volker.Schier@fen-net.de), November 15, 2001.