Re-Exposure Apparatus for Black & White Films

Discussion in 'Black and White' started by dw|1, Sep 1, 2009.

  1. I have developed my own BW negatives for 20 years.
    I am now delving into the carcinogenic world of BW reversal processing.
    As with any film development, consistency is key to getting repeatable results.
    I will use the Ilford Reversal Process as published, with PanF 50.
    My question is in regards to the Re-Exposure, ie., fogging, process.
    It seems several folks favor just holding it up to a diffused window light source for a
    minute per side. This seems a little inconsistent, so I'm just wondering if there is some
    consumer-grade apparatus for re-exposing the film in a precise and consistent manner.
    I have not been able to find such an apparatus by searching the internet.
    So, ideally, somebody here is going to send me a link to a < $150 re-exposure apparatus ;)
    Alternatively, I have a large softbox with a single baffle that gets little use. I was thinking
    about adapting it to accept a 100watt bulb, and laying the film diagonal across the panel
    for 60 seconds per side. My only concern with this is that there is a slight hot-spot in the
    middle, by about 1/2 stop, which might lead to the middle frames being re-exposed
    differently from the edges.
     
  2. Addendum: I suppose I could always go the flourescent tube route. Easy to rig that up.
    Any thoughts on the tube "wattage" or re-exposure time for this method.
     
  3. my old FR speial plastic film developing tanks originally had black reels
    later had white plastic reels
    I don't see why these reels or metal wirew reels would not allow you to easily re-expose film
    later processwes chemically "
    re-exposed" the film
    the Kodak direct positive kit had a chemical packet that chemically re-exposed the film.
    I still have a couple of the packets somewhere.
     
  4. It's not carcinogenic as long as you don't use dichromate in the bleach step.
    The II° exposure is fine using a common fluorescent tube or, better yet, a compact fluorescent of say 21w or better.
    Don't take out the film from the reel sa this may damage it. Exposing 2 to 3 minutes each reel side shoud be sufficient.
     
  5. I dont claim any expert knowledge in this area, however the way I was told to expose colour and B&W film during reversal processing was to place the reel (Paterson clear or series 4 white, it did not seem to matter which) in a white kitchen 2 pt mixing bowl (pudding basin) full of water and place it under the anglepoise desk lamp set a few inches above the surface of the water in the bowl.
    The white basin or bowl reflected the light to all parts of the film, and the water stopped it overheating (probably you could do away with the water in these days of low energy lamps)
    I always followed the same procedure and never had a problem, although the total number of films I processed in this way was only about 30 - 40 - hence I claim no expert knowledge. Also I only ever processed a single film at a time - if you have several films on the go at once you may need to devise a more sophisticated technique.
    I always understood that you exposed to completion, ie ALL remaining silver was totally exposed, so provided you had enough exposure, the actual amount was irrelevent. Again - this was only supposition on my part, not scientific fact.
    Hope these musings from long ago help a little.
     

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