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  1. #11
    glbeas's Avatar
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    Quote Originally Posted by BobF
    Phil, the Ilford site lists an anti-halation backing for roll (120) and sheet film but none for 35mm. Makes sense as presoak of 35mm pours out clear while presoak of sheet and roll pours out black. I use all three types of FP4.

    The acetate they use on 35mm has some kind of tinting that isn't on the roll or sheet film but to me it looks neutral grey, not blue. Densitometer readings on roll and sheet film (FB+Fog) are half that of the tinted 35mm acetate. Readings of .16+/- for roll and sheet versus .32+/- on my old analoge weston densitometer.

    Don't ask me why they do this or what affect it has, but if anybody knows please chime in.
    They do this to quench the light piping by the film, a la fiber optics. Kodak High Speed Infrared is bad in this respect and it's one of the reasons to load the film in the dark. The other being the felt is not reliable for stopping IR.

  2. #12

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    Quote Originally Posted by BobF
    Don, the base for 35mm is 5mil, for 120 is 4mil, but for sheet is 7mil. I think this means that it has to have some kind of color added to the thinner 35mm base to get the tint.

    I was thinking about the blue(35mm) and brown(sheet) color that phil mentions vs. the neutral grey I get on all formats. I use D76 and he was using Pyrocat which I understand leaves a usually green stain. I have never used Pyrocat HD but could this be the difference?
    BobF

    In my experience and in the literature from Sandy, Pyrocat usually leaves a brown stain not green. In 35mm FP4 there is a colour shift away from the usual but there is still a blue/grey undertone. In sheet FP4 there is no blue undertone at all. It all comes out in the presoak.

    Phill
    It is not tradition that secures the survival of our craft, its the craft that secures the survival of our traditions.

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