By your description of significant curl and high Dmin the 35mm film is
probably coated on polyestar support (PET). To reduce light piping it is
common to add dye to the support. Nearly all 120 and 135 roll films use
cellulose tri-acetate
not PET because CTA film will not curl as much and does not light-pipe.
Light-piping can cause light fog because the support allows light to travel
laterally through the support. Sheet film uses polyestar to obtain less
physical distortion and better flatness. Light piping does not cause
problems in film holders.
Robert L. Shanebrookwww.makingKODAKfilm.com
On Saturday, October 21, 2017, 1:38:09 AM EDT, `Richard Knoppow
<dickburk@xxxxxxxxxxxxx> wrote:
I meant only to examine the support to see if it had any extra density.
Normal roll and sheet film support is completely clear. If it is what you are
seeing is plain old fog.
On 10/20/2017 3:27 PM, Tim Daneliuk wrote:
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
WB6KBL
