The process is not really new, it is known since about a century. There are very few specialized black and white reversal films on the market. Agfa Scala is yet produced but for how long? Amateurs can buy B&W reversal developing kits but they are expensive.
So pushed by one of my large format friends (Emmanuel Bigler) I decided to make a little research to find out if it were possible to use common B&W negative films.
I did not invent anything, I simply read articles found on Internet and classical literature in this domain then I made tests to obtain a standard procedure usable with good results.
This article deals only of 120 roll films, an article about sheet films will be written in the future.


Security
(Usual disclaimer: « I can not be responsible bla bla bla… » but you have to know that some of these chemicals are dangerous)
We will use chemicals less or more toxic or aggressive
Especially those who are used for bleaching
So please read the following advice
- read and understand the material safety data sheets (MSDS)
- store these products out of reach of children, other family members and pets
- Wear security glasses and gloves whiles preparing the solutions. Keep the security glasses during the process (I experimented throws during rinsing!)
- Work in an airy room.
- I always have an emergency eye wash of Diphoterine (solution developed in France as an eye/skin chemical splash water-based decontamination solution, the only product on which the substance is not efficient is hydrofluoric acid)


Chemicals and material needed:
Ilford PQ universal developer
Kodak Dektol paper developer
Potassium permanganate (pure at 98%)
Sulphuric acid pure
Sodium thiosulfate
Sodium sulphite
Sodium metabisulphite
Formaldehyde for Efke films
Tetenal fixer + Tetenal Harder solution
Precise scale, stirring paddles or a magnetic stirrer (very nice tool!), graduates, one 10ml glass pipette and a propipette (three way rubber bulb) for the use of sulphuric acid and a 500W bulb (I’m using a Philips 500W bulb).
Remark: most sources in the literature mention 100W bulbs (with reflector) but I prefer the 500W one because the risk in our case is more underexposure then overexposure.
It is possible to work manually but because I’m lazy and of course for repetitivity I’m developing with a Jobo CPP2.

The process consists of 6 steps (+ intermediate and final rinses).
First developer
Bleaching
Clearing
Light exposure
Second developer

For Efke films it is necessary to use a tanning(hardening) bath after the first developer because of fragility of gelatin.
Avoid this process for Kodak films!

You can mix the chemicals in advance with one restriction: Sodium thiosulfate has to be added to the first developer at the last minute. The mixed solution does not stay stable.
I always prepare developer with distilled water (or De-Ionized water) other bathes can be prepared with tap water.

A five minutes pre-wash with distilled water or DI water is possible but not essential. I tried the process with and without it, now I prefer without (I said I was lazy, the process is long enough...)
The bathes, except the fixer, are used only once then thrown.
Always use 300ml of solutions per film (in the 15xx Jobo drums). Less would not allow a full action of the thiosulfate and a part of the images will keep a kind of fog.

Measuring light
All the films were exposed with their nominal ISO value, I measured the high values of light (not the sky! but the clear parts from image where I wanted details) and I overexposed this measure of two steps. (I’m working with constant aperture).

- First developer
(Developing times see the above table)
PQ Universal diluted at 1+4 + 9,5gr per liter of sodium thiosulfate added just before use. 20°C
Jobo agitation is put on fast.

Films
Roll film 120 PQ Universal *

Base fog 1st developing times.
9,5gr/l of thiosulfate
Adox CHM 125.......0,016.....6mn
Agfa Agfapan 100..0,016......5mn
Agfa Scala 200......0,04.......8mn
Efke R100.............NM*.......8mn
Efke R25...............NM*.......4mn
Efke R50...............NM*.......4mn
Ilford Delta 100......0,05.......6mn
Ilford HP5+............0,15.......5mn
Ilford Pan F+..........0,16.......7mn
Ilford FP4+ ............0,08.......6mn
Kodak Tri-X 400.......0,2........6mn
Kodak Tmax 100.......0,05......8m30
Kodak Tmax 400.......0,14......8mn
Lucky SHD 100.........0,025....4mn

Nm*: non measurable even with eight layers (the very low values had to be measured with several layers)
* Some tests were done with Agfa Neutol NE (1+4 dilution) but not on all films, the results were good.

Please consider these times as a starting point, you will have to adjust them regarding your habits of light measurement. It is also possible to decrease a little the amount of thiosulfate and lengthen the developing times but you will have to perform the tests again.
.

Efke films: hardening bath
2 minutes
Formaldehyde at 37% 15ml
Sodium carbonate anhydrous 5gr
Water to make 1 litre

- Rinse
2 minutes (With the CPP2 I change the water every 30 seconds)

- Bleaching (1)
5 minutes
Potassium permanganate solution
Prepare two bathes:
A: 500ml water + 2gr of potassium permanganate
B: 490ml water + 10ml of concentred sulphuric acid
Mix A and B just before use
Very important drop slowly acid in water, NEVER water in acid!


- Rinse
2 minutes

- Clearing
3 minutes
Sodium metabisulphite 25gr + water to make 1 litre


- Rinse very energetically
5 minutes
About 10 water changes. At this point you can open the drum and rinse with a normal (low) light (25W). The last rinse has to be done with distilled water to avoid chalky marks during light exposure (if your tap water is hard water).
.


Expose to a strong light
4 to 5 minutes
The articles I read indicate 1m30s per face of film but there is no really a maximum (avoid solar light it’s really too strong). The real risk is to underexpose the film, so I
expose the film 4 to 5 minutes changing the face of the reel every 30 seconds.
The reel is facing the light between 2 and 3 feet (60cm to 1 meter)
With some training, you'll soon get an idea of the final result at this time.
Once this done we have a grey (sometimes yellow, it depends of film) film.

- Second developer (Attention: no thiosulfate this time)
Dektol 1+2: 5 minutes
Use of Dektol seems to avoid black silt on reel: the potassium permanganate procedure create with some films a kind of very fine black mud witch marks the reels.
Or
PQ universal 4 minutes at 1+4 (or 8 minutes at 1+9)

Rinse
2 minutes

Fixing
4 minutes
Tetenal fixer + Tetenal Harder, 30ml harder per liter of fixing bath

Rinse as usual
One minute in distilled water(or DI water), one minute in wash aid (20gr of sodium sulphite, 3gr of sodium metabisulphite water to make 1 liter), 5 water changes in Jobo and 10 minutes in running water.

Last rinse
1 minute
Distilled water(or DI water) + 5ml per liter of photoflo

Dry
(It’s always too long!)

Some tips

- Do not lengthen the bleaching or/and clearing bathes or you will get a nice fully washed layer.
- If final image is too dark increase the first developer times or if too light decrease this time (30% is a good measure)

In matter of conclusion it is easy to develop your own Scala by yourself
and the tests proved that we have cheaper replacement possibilities.
Choose the films which have the lighter base fog; my personal choice is going to Agfa Apx 100, Ilford FP4+ and HP5 and also the Efke films (I like their grey tonal range).
One remark about Efke the protection paper seems to be too thin I got problems loading films under strong daylight.
I tried the Chinese film Lucky, but only “for fun” he always keeps a pink layer and the results seem not to be stables. I did not have good results with Fuji Acros Fuji films but I will pursue the tests for them.

(1)Why the choice of Permanganate instead of dichromate:
There is a second method of bleaching using potassium dichromate but first the permanganate is less toxic and second in the silver salts transformation there is a phase of chrome salts witch are also toxic.

And then?

You have now the pleasure to examine your own B&W transparencies over a light box, for the large format (8x10) you can use an overhead transparency projector(I tested it, its really nice).

Annexes:

Chemicals and their CAS numbers (this number allow you to search and read the MSDS)
Potassium dichromate 7778-50-9
Potassium permanganate 7722-64-7
Sodium thiosulfate 333-20-0
Sulphuric acid 7664-93-9
Sodium sulphite 7757-83-7
Sodium metabisulphite 7681-57-4
Formaldehyde 50-00-0

MSDS links:
http://www.inrs.fr (french)
http://www.sante.gouv.fr/htm/dossier..._ei.htm(french)
http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB (english)
Or you can use a search engine; just type CAS xx-xx-xx

Diphoterine:
http://emballage.com-leader.com/raja...0-1179400.html

Links about B&W transparencies:

http://romain.buet.free.fr/index_chi.htm
http://www.bonavolta.ch/hobby/fr/photo/slidesbw.htm
http://www.binbooks.com/books/photo/i/l/509E6AE264
http://lavender.fortunecity.com/lave...developer.html
http://www.tech-diy.com/reversal_formulas.htm
http://www.profotos.com/education/pr...ns/index.shtml
http://www.kodak.com/global/en/profe...roces-tech.htm

Bibliographies:
P. Glafkides: “Chimie et physique photographiques”
Gevaert Photo: “Formules photographiques 1943”

Chemicals receipts:
Bleaching bath:
Solution A potassium permanganate: 2 to 3gr (max) per solution liter (I’m using 2gr)
2gr permanganate + water to make 500ml
Solution B Sulphuric acid concentrated 10ml/l
Water 490ml + concentrated acid 10ml
Mix just before use

Clearing bath:
Sodium Metabisulphite 25gr + water to make a liter

Tanning bath:
Formaldehyde at 37% 15ml
Sodium carbonate anhydrous 5gr
Water to make1 liter

Wash aid bath:
Sodium sulphite 20gr
Sodium Metabisulphite 3gr
Water to make one liter

Have fun !
May 2005 Claude Eichel