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Thread: Longest possible exposure time for collodion?

  1. #1

    Join Date
    Apr 2010
    Santa Fe, NM

    Question Longest possible exposure time for collodion?

    Hey to all of the wet plate shooters here,

    In your experience, what's the longest exposure time you've been able to milk out of a plate before it gets too dry?

    Just curious if people's experiences are similar or varying (and why!).


  2. #2

    Re: Longest possible exposure time for collodion?

    Depends on the weather--in hot dry desert like conditions I found that after two minutes exposure (not counting time in the holder, before and after exposure) my plates were showing scaling and uneven exposure. In the cool pacific northwest I have gone up to five minutes with no signs. Of course, plate size, camera size, and the construction of your holder are also important factors.

  3. #3

    Join Date
    Sep 2003

    Re: Longest possible exposure time for collodion?

    It also depends on the formula. Collodion iodized with sodium salts will dessicate quickly. I believe ether will evaporate quicker than ethanol due to the latter's water content and that could affect the rate.

    Some folks put a damp fabric on the back of the plate to extend the useful working time. Supposedly that keeps the humidity higher in the holder and gives a bigger window.

    The longest I've gone is probably around 6 minutes on a cool (68F/20C) day. But with sodium salts I also got drying marks at around 2 minutes under similar conditions.

    Some people have reported doing up to 15 minutes or longer in winter.

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