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  1. #1

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    How strong to tap the bottom to free the air bubbles?

    How strong to tap the bottom of the tank to free the air bubbles? Just a gently tap?

  2. #2
    MattKing's Avatar
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    Fellipe:

    This is a good question, but really hard to answer over the internet.

    I give it a good slow but firm rap on a cushioned surface - something like a countertop with a towel on top.

    You don't want to break the tank!

    Matt

  3. #3
    Curt's Avatar
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    I've even given it a tap on my left palm, it doesn't have to be slammed down on a concrete floor. Some people use the term "rap" even, I don't now what he big difference is but a gentle tap on a cushioned surface just like Matt says is exactly what I do.
    Everytime I find a film or paper that I like, they discontinue it. - Paul Strand - Aperture monograph on Strand

  4. #4

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    thanks guys

  5. #5
    Anscojohn's Avatar
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    Quote Originally Posted by Fellipe de Paula View Post
    How strong to tap the bottom of the tank to free the air bubbles? Just a gently tap?
    ******
    I give it a good thump by bringing the SS tank down on the heel of my hand after the last tip over of each agitation cycle. I guess the hand is kind of going up to meet it. Not hard enough to hurt, though.
    John, Mount Vernon, Virginia USA

  6. #6
    gainer's Avatar
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    How do we know without opening the tank to look? Maybe an experiment with outdated or sacrificial film would be in order. I use such vigorous agitation that there sholud either be no bubbles or bubbles everywhere, But I still give it a good rap when I set the tank down.
    Gadget Gainer

  7. #7

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    Quote Originally Posted by gainer View Post
    How do we know without opening the tank to look? Maybe an experiment with outdated or sacrificial film would be in order. I use such vigorous agitation that there sholud either be no bubbles or bubbles everywhere, But I still give it a good rap when I set the tank down.
    Just look in the tank when you are doing your wash, or even photoflo rinse. Suffice to say I'm not 100% sold on tapping the tank. I've seen bubbles stick even when doing the photoflo rinse with distilled water. If they are sticking with THAT combination of liquids in the tank I highly doubt a few taps will get them loose during the development stages. Small bubbles have a tremendous amount of surface tension and a little tap will NOT make them go away.

    I use the twirling stick to prevent additional air bubbles from forming and live with the comfort that every 25 seconds any bubbles on the flim will be relocated and should have minimal effect on development.

    Ok: que the poster that will say he/she has been developing film since it was made from stone and developed in dinasaur urine to say I am wrong...

  8. #8

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    Actually, I found dinosaur urine makes a good stop bath.

    Sorry, I couldn't resist.

    Peter Gomena

  9. #9
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    Some of the kids in the darkroom where I work sound like they are driving nails at times - way too hard. Just about the same force as the tank would encounter if you dropped it from about 2mm height works for me (best estimate I can come up with in words )

    - Randy

  10. #10

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    Fill all the way to the top expells most of the air. the raps mentioned above should be sufficient. When you finally open the lid and find foam you will know there was air. If there are no bubble marks on the film your technique is okay.

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