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  1. #1

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    Oct 2009
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    Dry hot press dents prints and mat boards...

    When I use my dry hot press, I sandwich prints and backer boards in between two sheets of mat boards for protection and a release paper for non-stick. These boards and release paper are re-used.

    Apparently, when I was drying 8x10 double thickness FB paper, it made an impression on the mat board. When the same mat board was subsequently used to mount a print onto a backer board, it made an impression on the backer board.

    How do I prevent this? Is the platen pressure too high? Is there a process to un-dent (is that a word??) release papers and mat boards used in pressing? It will get expensive if I have to use new boards each time.
    Develop, stop, fix.... wait.... where's my film?

  2. #2

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    I had this problem but seemed to have cured it so far by:-
    a) Squashing the two mount boards as hard I as I could in the heat press for 24 hours at a fairly high temperature..
    b) putting thin card sheets between the print and the thicker mount boards.

    Seems OK at the moment but I am still a little anxious.

    Tony

  3. #3
    glbeas's Avatar
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    Sep 2002
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    Try a scrap thats been dented and steam the area. If it acts like wood it will swell back to level. Then you can clamp it back in the press and dry it out.
    Gary Beasley

  4. #4

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    Dec 2007
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    Dry Mounting

    I discontinued the use of the release sheet years ago and never had the problem you've experienced. And I've re-used the cover boards many times. Here's an excerpt from the darkroom notebook I've assembled (covers all my processes) that includes a bit on dry mounting. My press happens to be large enough for 16x20 prints. The process is taken largely from AA "The Print". I only use double weight silver gelatin paper, so you would need to experiment if you use any other kind. Note the extreme attention paid to dusting.

    EXCERPT:

    Dry out mount board and two 20x25 cover boards (same material as mount board).
    - Place mount board in press separately for 45 seconds (press not latched).
    - Open press, then repeat for 30 seconds.
    - Allow boards to cool.

    Dust print on both sides and lay face-down on a dusted cover board.

    Cover print with a dusted sheet of dry mount tissue that overlaps the print edges.
    Using tacking iron, tack tissue to print (with moderate pressure).

    Trim print and tissue together to final size, then dust both sides.

    Dust mount board.

    Tack print to mount board.

    Dust both print and mount board & place between the two pre-dried cover boards.

    Place additional cover board on top (all 3 boards are same material as mount board).
    Final stack-up should be as follows, listed from top to bottom:
    - Cover board *
    - Cover board *
    - Print face-up on mount board
    - Cover board *
    * Larger than press platen

    Place stack-up in press for 3 minutes (longer than mfr recommended time due to use of two boards above print).

    Remove from press and cool for about one minute. A moderate weight helps prevent print curling / warping.

    When cool, bend mount board severely (away from print) between diagonal corners. If print snaps off mount board (insufficient bond strength), re-insert same stack-up into press for longer time and consider higher heat.

    Remove from press and cool several minutes under a weight. Re-check adhesion by bending mount board.

  5. #5

    Join Date
    Aug 2005
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    Los Alamos, NM
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    Instead of a release sheet and covering mat board, I've been using a piece of foam on the bottom and a large sheet of aluminum foil on top. The aluminum foil is disposable, in case it gets wrinkled or dirty, but it acts as a good release sheet and conducts heat well. At first I was wary of this scheme, but I've been using it for about 10 years now without any funny attributes transferred to the prints. It is important to keep everything flat, even, and clean.

  6. #6
    wildbill's Avatar
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    Nov 2004
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    You don't need much pressure since the heat is doing the work. I don't use much pressure at all. Your press should be adjustable.
    www.vinnywalsh.com

    I know what I want but I just don't know how to go about gettin' it.-Hendrix

  7. #7

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    Yes, it IS adjustable. How do I guage the appropriate pressure? Is slight deflection on bottom form enough?
    Develop, stop, fix.... wait.... where's my film?



 

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