Developing film twice.

Discussion in '35mm Cameras' started by Gregory L. Hansen, Dec 14, 2005.

  1. The local one-hour photo labs have very little ability to do special
    requests like pushing film. And surely for good reason. But what would
    happen if they just ran it through the developer machine twice? As I
    recall, at some point it goes through a fixer bath that, well, fixes it,
    and maybe it can't be developer further at all after that. But my
    knowledge of the chemistry is really pretty sketchy.
    Gregory L. Hansen, Dec 14, 2005
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  2. Gregory L. Hansen

    Bhup Guest

    once its fixed that it
    Bhup, Dec 14, 2005
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  3. I suspected that. Thanks.

    Gregory L. Hansen, Dec 14, 2005
  4. can learn to do it yourself. It's really easy. your
    local community college, high school or college....see if there is a photo
    student who would do it. Know though that things can go wrong.
    Gene Palmiter, Dec 14, 2005
  5. Gregory L. Hansen

    columbotrek Guest

    You don't need a dark room to develope film or slides. Just the
    chemistry, the tanks, and a changing bag or a dark closet. A book on the
    process helps a lot too. You will need some tools as well such as a
    thermometer, measuring cups and special containers but they are minor in
    columbotrek, Dec 14, 2005
  6. As others have told you, once it has gone through the fixer all the
    undeveloped silver salts are removed, and that's it. However, if the
    film was put through the developer twice without having been fixed in
    between, then development would continue and you would get a grossly
    over-developed film. Assuming it is negative film, the highlights would
    be completely blocked up and the contrast would go through the roof; the
    results would almost certainly be unusable. It is possible to gain some
    extra film "speed" by using a shorter exposure and a longer development
    time, but this would usually only be about 20-30%, and the film has of
    course been underexposed to compensate (though you still get increased
    contrast). It is however difficult to do this in a mechanised C-41
    process line, as the timings are usually fixed. Also, they usually put
    the film through all the baths (including fixer) with no chance to get
    it out in mid-process.

    David Littlewood, Dec 14, 2005
  7. Gregory L. Hansen

    Matt Clara Guest

    I worked with a lab that could push process by simply shutting off the
    machine while the film was in the soup, before the stop and fix stages.
    Unfortunately, they could only do it with 24 exposure rolls, as a whole 36
    exp. roll was never all in the soup at one time.
    Matt Clara, Dec 14, 2005
  8. Wow, that sounds a but hit-and-miss!

    David Littlewood, Dec 14, 2005
  9. Gregory L. Hansen

    no_name Guest

    Yup. Once it's fixed there ain't gonna be any more development.

    Fixing removes the undeveloped silver from the film emulsion. Once you
    do that, there's nothing to develop.

    For B&W negatives, if they're a little underexposed, you can selenium
    "tone" the negatives to give them a little more oomph.

    Normally selenium toner is diluted 20:1. If you're going to tone the
    negative, mix it at 3:1

    What would happen if you just made a special instruction on the
    mini-lab's bag and told them to process it as a higher speed film?
    Process ISO 100 film as if it were ISO 200.
    no_name, Dec 14, 2005
  10. Gregory L. Hansen

    Jim Guest

    Nope. After going through the fixer, there are no light sensitive chemicals
    left on the film.
    Jim, Dec 14, 2005
  11. Silver? My knowledge of the chemistry really is pretty sketchy. I
    thought they used light-sensitive dyes and that silver was old B&W stuff.
    It's the same process for all film speeds. They pull a bit of film out of
    the cartridge, tape it to a leader card, and insert it into the machine
    and close the top. Then feed in the next while the first is still going
    through the workings. There could be two films of different speeds taped
    to the same leader, it doesn't matter, the timing and everything else is
    the same.
    Gregory L. Hansen, Dec 15, 2005
  12. Of course there's silver. That's the light sensitive material. The dyes
    are coupled.
    Michael Weinstein, Dec 15, 2005
  13. To be accurate, it's not silver, but silver halides (mostly bromide,
    with perhaps some chloride and iodide). Then, where light has hit one of
    the grains, the action of developer is to reduce the silver bromide to
    metallic silver, which is in very fine specks and thus appears black.
    Silver bromide is soluble in fixer, whereas metallic silver is not
    (well, actually it will dissolve, but only slowly, which is why fixing
    time should not be over-extended).

    This process forms the basis of almost all film and photographic
    printing paper. Colour films use the action of the developer to deposit
    coloured dyes and then remove the silver later, and use three (or more)
    layers and filters to create the various colours, but the key
    light-detection process always involves light-sensitive silver halide
    and its reduction by a developer.

    David Littlewood, Dec 15, 2005
  14. Color film must have different silver-containing molecules that react to
    one range of visible light but not others, and then latch on to one type
    of dye but not the others.

    After all this time, I wonder whether a better type of film (more light
    sensitive, finer grain) can be made, but simply isn't because it couldn't
    be developed in existing labs.
    Gregory L. Hansen, Dec 15, 2005
  15. Well, kind of. There are 3 layers with different sensitivities to red,
    green and blue light, but this is caused by organic sensitisers in the
    silver halide crystals.

    Very brief (and simplified) summary:

    Top layer: unsensitised (and thus only sensitive to blue light
    Yellow filter
    Second layer: sensitised to green light, would record B + G but B
    filtered out so records G only
    Third layer: sensitised to red light, would record B + R but B filtered
    out so records R only
    Anti-halation coat (stops light bouncing back
    Film base

    The top layer contains colour couplers (organic molecules which react
    with used developer to form dyes) which are yellow
    The second layer contains couplers which (with used dev) form magenta
    The third layer contains couplers which form cyan dye.

    Thus each layer records one colour and ends up as its complimentary one.

    For more detail (and how this is extended to reversal film) I suggest a
    little reading or web search. Note Kodachrome works somewhat
    differently, but the principles are the same.
    The holy grail! In fact, it is quite impressive how much sensitivity and
    grain have improved in the last 30 years.

    David Littlewood, Dec 15, 2005
  16. Cool. Thanks.
    I don't know about grain, but 800 speed is still about as fast as film
    seems to get unless you go to specialty suppliers. 1600 or 3200 just
    doesn't seem to be carried by the local Ritz, Walgreens, or MotoPhoto.
    Gregory L. Hansen, Dec 15, 2005
  17. Gregory L. Hansen

    no_name Guest

    You could be right.

    My experience with hand processing color is a little dated. I seem to
    remember the silver in the emulsion held the dyes until development.
    Once the image was developed and fixed, the silver was washed out to
    leave the dyes behind.
    no_name, Dec 15, 2005
  18. Gregory L. Hansen

    no_name Guest

    Remember Kodak's Ektar films? Based IIRC on the T-grain developments
    that gave T-Max, they had an Ektar 25 film that they touted as being the
    color negative "equivalent" of Kodachrome 25.

    The "grain" was as good, but there's no color negative film that really
    had the color impact of Kodachrome.

    OTOH, it was a whole lot more forgiving in its exposure latitude.
    no_name, Dec 15, 2005
  19. Never used it; didn't really like colour negative film.
    Yes, I used to use a lot of Kodachrome. I think they rather lost the
    plot a decade ago though, and failed to keep up; Fuji reversal films
    overtook them. The much-touted (and true) dark stability of Kodachrome
    tended to obscure a horrifyingly poor light stability.
    As are all negative films.

    David Littlewood, Dec 15, 2005
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