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  1. #1
    Claude's Avatar
    Join Date
    Jan 2005
    Large Format

    Processing your own Black and White transparencies

    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.

    (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
    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.

    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.
    PQ universal 4 minutes at 1+4 (or 8 minutes at 1+9)

    2 minutes

    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

    (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).


    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://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB (english)
    Or you can use a search engine; just type CAS xx-xx-xx


    Links about B&W transparencies:


    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
    Attached Thumbnails Attached Thumbnails expositionp.jpg   ruin_scalap.jpg   ruinfp4p.jpg  

  2. #2
    Sean's Avatar
    Join Date
    Aug 2002
    New Zealand
    Multi Format
    Blog Entries
    Comments from the previous article system:

    By Jordan - 03:43 PM, 07-08-2005 Rating: None
    Claude, this is nice. Are you aware of the informational PDF on the Ilford web site about processing? It provides reliable formulae and times for reversal-processing Pan F and FP4 Plus.
    I have a couple of comments on your process:
    (1) Instead of re-exposure and re-development, you can substitute a sepia-toning bath. This directly converts the silver halide to silver sulfide, and you get nice warm chocolate-coloured slides. The effect is pleasing with Pan F. With TMAX films the colour is very "orange" due to the crystal phases of the silver halide.
    (2) You can substitute sodium bisulfate (not bisulfite) for the sulfuric acid. Sodium bisulfate is a solid that dissolves in water to create the equivalent of sulfuric acid. It is sold cheaply for people who have back-yard pools, as an agent to reduce the pH of the pool (trade name here in Canada and also in the US is "pH Minus&quot. If you need a formula, I can provide it.
    (3) I agree with you for the most part about the permanganate. However, the guy behind DR5 (www.dr5.com) has reported some archival problems with permanganate. Also, it must be mixed right before use since it goes bad quickly (dichromate is stable).
    I have a summary of B&W slide options here: http://www.photosensitive.ca/BWslides.shtml

    By Claude - 05:05 PM, 07-08-2005 Rating: None
    Hello Jordan,
    thank you for your comments and links, it's allways interesting to exchange informations. I knew the sepia process but .... I do not like the chocolate color
    I allways mix my chemicals just before use. What I forgot to say was that permanganate must be strongly mixed. (Even with a magnetic stirrer).



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