BTZS tube Developing Times

Discussion in 'B&W: Film, Paper, Chemistry' started by esearing, Dec 9, 2004.

  1. esearing

    esearing Subscriber

    Aug 17, 2004
    North GA
    4x5 Format
    I read some where, possibly here, that BTZS tubes shorten the time for developing compared to Trays. I thought I might make a tube and try it.

    1) Is there a rule of thumb for reducing the time in tubes? (assume PMK averages 12-14mins in tray, what is change in tube time?)

    2) What is amount of developer needed for 4x5? 1/2 tube, 3/4 tube? more less?

    3) Is contrast increased/decreased by the constant spinning in a waterbath?

    4) Would PMK require a change of developer midway due to oxidation? or would I just use more developer?

    thanks in advance!
  2. Donald Miller

    Donald Miller Member

    Dec 21, 2002
    Large Format
    1. I believe that typically the tray times are extended by 10-15% over rotary processing times.

    2. That would depend on the volume of developer to square inches of film. I don't use PMK so you will need to determine that based upon PMK recommendations.

    3. Contrast of a given film (within the limitations of the emulsion) is increased by increases in any of the following individually or collectively...

    a. strength of dilution

    b. time

    c. temperature

    d. agitation

    4. PMK has not been generally recognized as a developer for rotary processing. At least that is my information. There have been some changes in recommended procedures with this developer. This may be one of them. Best to check further.

    Good luck