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  1. #11

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    Desiccant

    Oooops. Looks like one of my posts did not make it. I will try again.

    I am not sure what the reason is for the desiccant. It is common with commercial lab grade vacuum drying systems---see the example below.

    http://www.coleparmer.com/catalog/pr...sp?sku=0891260

    I think I will proceed with the experiment in the new year and will report back my results. There is so much experience with APUG members that I thought it was worth a try to tap into the collective knowledge and see if some one had already had a go at vacuum drying. I do appreciate all your replies and ideas---most grateful for the interest.

    I like 135 format, but tend to push its use to an extreme. With a rangefinder camera and optics and the new emulsions (TMAX-2 400), I find it possible to get an extraordinary amount of information content off of a negative.

    When I use to scan with my Imacon 343, the dust issues never showed to this extent---but that was at 3200 ppi. Now I am at 6300 ppi with the X1 and its a whole new ball game.

    I do occasionally get film back from the lab that 'lucks out' and is nearly dust free, so it is not a scanner issue. But it may be a good idea for me to check reference with a XTOL D&D to make sure it is not a PyroCat issue---though I have seen the problem over multiple batches of developer. Further, I have seen the same trend of problems with tests at different labs, and even with color negatives.

    Most grateful for the interest---I will report back when I have done the experiments.

    Pete

  2. #12
    michaelbsc's Avatar
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    Quote Originally Posted by Nicholas Lindan View Post
    It gets depressing, if I could sell 10,000 of the bleedin' timers they would sell for $29.95 each [though they would have to come in a tacky made-in-china plastic box, instead of a tung oil varnished, stained, finger-joined cabinet work enclosure].
    Boy I understand that feeling. In my line of work we usually build *ONE* of whatever it is, then never see another one. Every customer on the planet wants to know why things aren't cheap like TVs are in Wal-Mart. You can't get them to understand that the prototype TV wasn't so cheap, and what they're ask us to quote is really just like a prototype.

    I'll take one in a plastic box if you've got it.

    MB
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  3. #13
    Martin Aislabie's Avatar
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    Pete, you are quite right - pulling a vacuum will boil off the water on your films.

    The drying cabinet for a vacuum would effectively need to be a Pressure Vessel - which is a serious piece of Engineering

    To pull enough vacuum to dry the film, you would need to reduce the pressure inside the drying cabinet down to only a few Pascals (I can tell you how many if you want to persist with the idea)

    However, it will have to be one heck of a drying cabinet - with a hermetically sealed opening and cabinet sides that will each sustain aprox 6 tonnes of load without deformation.

    Half inch think steel plate will do the trick for the walls.

    No idea who you would talk to about a sealed opening - do you know anyone in the Submarine or Pressure Vessel manufacturing industry?


    Alternatively you could try a sealed volume and a Chemical Desiccant Salt arrangement - but I have no idea how you control the chemical dust levels to the levels you require


    Or - you could go back to your Lab and ask them about their levels of cleanliness and general house keeping – they obviously can do it, as they meet your standards – if only occasionally

    Martin

  4. #14
    Nicholas Lindan's Avatar
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    Quote Originally Posted by michaelbsc View Post
    I'll take one in a plastic box if you've got it.
    Well, we haven't made one in a plastic box yet. Lets see ... $80,000 for the tooling, $29.99 for the timer.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  5. #15
    aparat's Avatar
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    I can share my experience with you because I used to have the exact same problem you describe. I solved it by using a Senrac on-reel dryer. After a quick soak in distilled water with Photo Flo, I dry the film on-reel for 8 min. with warm air, followed by 8 min. of cool air. The negatives are absolutely spotless. However, the film curls. I solve it by winding it against the curl and putting it in a 1 inch tube for a couple of hours. Works great!

    The other source of dust is your scanner, and in particular the film holder. If you're using a glass holder, you will have to clean the holder really well.

    The other thing that works great is an anti-static film cleaner like this one. It works wonders, at least for me .

    I second the advice about humidifiers.

    Hope this helps.

  6. #16

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    Quote Originally Posted by Pete Myers View Post
    Dear Group:
    I would appreciate a bit of information from the photo
    emulsion engineers and experts on methods of advanced
    film drying post development. Pete Myers Santa Fe, NM
    The accumulation of dust on film is a function of time.
    All things being equal, the dryer the film at start the less
    time required. So first eliminate the surface water using the
    designed for film eight blade squeegee. A pre or post soak in
    alcohol may be possible although I do not know if it would be
    compatible with squeegeeing.

    I squeegee for fast drying. I find no cabinet needed. If you
    try the eight blade be sure it and your film have had a soak
    in a weak PhotoFlo solution. Draw it slowly down the full
    length of the film. Dan

  7. #17
    CBG
    CBG is offline

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    Back to basics. No extreme measures until you've eliminated the usual suspects.

    If your film comes back from other labs with less or no dust issues, your current lab is the likely problem.

    Do your films, when processed by other labs, have the same issue? If so, you may be the source of the dust problem. Anti static brush and various measures may help.

    Best,

    C

  8. #18

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    I'm going to venture that scanning a 400 speed film at 6400dpi isn't resolving 1000 of specs of dust, but maybe it's the films structure you're seeing. Might be wrong. I'd try asking around in scanner or digital forums to see if they can offer ideas in this direction. Just a thought.

  9. #19
    wogster's Avatar
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    Quote Originally Posted by GraemeMitchell View Post
    I'm going to venture that scanning a 400 speed film at 6400dpi isn't resolving 1000 of specs of dust, but maybe it's the films structure you're seeing. Might be wrong. I'd try asking around in scanner or digital forums to see if they can offer ideas in this direction. Just a thought.
    You know, I was thinking along that line as well, there is a limit to scanning, where you start to see the structure of the film itself, which isn't perfect..... Same goes for enlarging, for example a 4x6m image from a 35mm negative will look pretty ugly, same thing from an 8x10 negative will look pretty good.
    Paul Schmidt
    See my Blog at http://clickandspin.blogspot.com

    The greatest advance in photography in the last 100 years is not digital, it's odourless stop bath....

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