yes or no to Hypo Eliminator?

Discussion in 'The Darkroom' started by kbova, Jan 3, 2006.

  1. kbova

    kbova TPF Noob!

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    In the past I have always used hypo eliminator when processing B&W negs. It seems some folks feel it isn't required anymore.... what are your thoughts?

    k-
     
  2. Hertz van Rental

    Hertz van Rental TPF Noob!

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    If you wash your negs properly then you do not need to use hypo eliminator. It's main function is to remove hypo from the Baryta base of fibre paper anyway.
    Film substrate does not absorb water or chemicals so you are only removing the chemicals in the gelatine emulsion.
    Method:
    Fill a bucket with water and get it to 20C.
    Fill the processing tank with water from the bucket.
    Agitate continuously for 1 - 2 minutes then empty.
    Repeat the process.
    If you do 12 changes of water then the chemical content of the film emulsion will be down to 0.025%. 13 changes will give you 0.0125% and 14 gives less than 0.006% which is well within archival quality limits.
    Each time you do a wash, the chemical content in the neg is halved - do the maths. I have used this method for 30 years using only 12 changes and never had a problem.
    If you are using a force film washer then you can use hypo eliminator to cut down washing times, but you have to wash the hypo eliminator out afterwards. I could never see an advantage.
     
  3. benjyman345

    benjyman345 TPF Noob!

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    Hi,

    I have a couple of rolls of B&W film which I have previously developed and am not convincd I washed them thoroughly. Is there anything I can/should do now at this stage?

    BTW is hyp clearing agent much use for washing film?a

    Also, when washing film with running water is it ok to use water which is at a different temperature to that of development?

    thanks
     
  4. Helen B

    Helen B TPF Noob!

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    " Each time you do a wash, the chemical content in the neg is halved - do the maths."

    It is a lot more than halved. Five washes will probably bring film to archival limits, six is perfectly safe. Using an alkaline fixer will reduce the need for washing, as will two-bath fixing, which can also increase the capacity of the fixer.

    Here is a Wiki on washing.

    Never, ever use hypo eliminator. Hypo clear is OK, but not always necessary for film, particularly if an alkaline fixer has been used. There is some confusion over naming, I think, because some hypo clearing agents may be called hypo eliminators - I'd have to look into it to be sure which ones.

    You can rewash film that you think is poorly washed.

    Try to keep the wash water within, say, 5 °F of the previous processes. It is difficult to give a hard-and-fast rule, because different films have different responses to variations in temperature when wet. The effect of a sudden temperature change may only show itself as a small increase in graininess. If you are using changes of water it is easy to get the wash temperature to within 2 °F of the other chemicals. I would not recommend running water washes in most situations.

    Best,
    Helen
     
  5. benjyman345

    benjyman345 TPF Noob!

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    If running water is not the best option... do you suggest the 5 10 15 20 agitation method... where you fill tank with water agitate 5 times empty and repeat with 10 agitations etc etc...

    thanks!
     
  6. Helen B

    Helen B TPF Noob!

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    The reason I suggest washing with changes is because of the temperature control issue. I think that many people, including myself, apply a paranoia factor to the cycle you mention. I give six washes, each 30 inversions followed by about a minute rest. I consider that to be a large paranoia factor, especially as I use two-bath alkaline fixing.

    Best,
    Helen
     

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