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  1. #1
    SchwinnParamount's Avatar
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    Water Vs. stop bath and film development

    In the last couple of months, I've seen odd density variations in my Plus-X and FP4+. On the long edges of each frame is a subtle area of increased density which runs the lenght of the frame.

    I develop in a steel tank with steel reels of course. For the last couple of years I've been using water as a stop bath as I was told I risk pinholes in the film when using stop bath of too strong a concentration. Rather than determining the correct concentration, I switched to water as it is 'supposedly' as effective as stop bath.

    I switched back to stop bath for my most recent roll of film and the density problem also disappeared. There were no other process changes. Is it possible that a water stop bath is less effective in stopping development at the edges of the film where it is in contact with the reels?

  2. #2
    df cardwell's Avatar
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    Is this sheet film or roll film ?
    What developer ?
    Fixer ?

    I think your hypothesis could be right, but it would help to complete the picture with your other variables.

    Think we can put together an APUG [COLOR=DarkRed]PBP [/COLOR]team in 2007 ?

    .
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  3. #3
    reellis67's Avatar
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    I always use a water stop and have never seen what you are describing. I use Ilford films (120 and 35mm), various developers (diafine, Microdol-X, Rodinal) and TF-4 fixer on steel reels/tanks. The only thing different about a water stop is that a small amount of developer remains active for a short time which increases adjacency effects slightly. Since my development times are always long, I suppose it makes no noticeable difference. How long are your development times?

    - Randy

  4. #4
    Loose Gravel's Avatar
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    I don't think it is the stop bath. I had problems with steel reels giving increased edge density. (Surge) I don't know for a fact, but I believe that the round reels allow eddies to form and provide increased agitation. Different types of agitation may change this, but I went to Paterson tanks and have never had the problems since.

    Oh yes, I have always used just water, never stop bath.
    Watch for Loose Gravel

  5. #5
    SchwinnParamount's Avatar
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    Quote Originally Posted by df cardwell
    Is this sheet film or roll film ?
    What developer ?
    Fixer ?

    I think your hypothesis could be right, but it would help to complete the picture with your other variables.

    Think we can put together an APUG [COLOR=DarkRed]PBP [/COLOR]team in 2007 ?

    .
    I am developing 35mm film in XTOL and the fixer is a standard hardening fixer made by a local company.

  6. #6

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    For a stopbath one does not need to use a strong solution. Vinegar 1:4 in tap water is pretty mild 1:8 should work well also...certainly, I believe it would be more effective than water. You could also try a 2% solution of sodium bisulphite.

    I would guess that the shorter the development time the more precision is aided by a stop bath. For instance to get predictible results with say Pan F+ in a developer at 5 minutes in a Rodinal solution compared to Delta 100 stand development of 45 minutes in Pyrocat HD solution the stopbath might be more helpful in controlling contrast variations when the time is short than when it is a great deal longer. In either case stopbath should be helpful in preventing stains etc.
    Claire (Ms Anne Thrope is in the darkroom)

  7. #7

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    How do you agitate? Do you agitate the stop bath?

  8. #8
    df cardwell's Avatar
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    I don't see the stop bath / water bath being a factor.

    It isn't in the water bath that long, and these films fix quickly.

    If it went away in the acid stop, stick with it. If it comes back, it wasn't the stop bath--- if it never comes back, it MIGHT be the acid stop.. but it doesn't really matter.

    .
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  9. #9

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    Quote Originally Posted by SchwinnParamount
    Is it possible that a water stop bath is less effective in
    stopping development at the edges of the film where it
    is in contact with the reels?
    My tap water is as alkaline as some developers I've used.

    More often that is a problem of the developing process
    and proper agitation. With a water stop, dilution of
    the developer and ph reduction are very swift.

    I've stopped using stops of any sort. Instead I use
    very dilute unadulterated sodium or ammonium
    thiosulfate. The two have a near neutral ph.

  10. #10

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    Oh another one who thinks surge marks exist. They don`t. They are simply areas that received the proper agitation compared to the areas that that did not so they are under developed. The usual cure is to try less and more gentle agitation. Guess what, the surge marks get worse.

    The reason the Patterson tanks works well is there is lots of free space for the developer to flow into while inverting providing full and complete agitation.

    Put only enough developer in the stainless tank to cover the reel fully and invert 5 to 7 times in 5 sec twice a minute. You want the developer to move and replace all the used developer across the full film surface. This is right off Kodaks website.
    You may also use a two reel tank with an empty reel on top and only developer to cover the bottom when at rest. Invert twice in 5 sec.

    In either case twist 90 deg when you set it down so as not to set up a particular pattern. Agitation must be vigorous and random.

    This is a guaranteed solution.

    Water and stop can work equally well although the acid can stop the development immediately. There is a grain penalty for either. I recommend you skip it altogether and go straight into the fix.

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