Re: Odd marks on negative -- help needed

[Don Roberts <droberts@xxxxxxxxxxxxx>]

Steve, I seem to see more drying marks on BW IR than on conventional pan
films.  I have no idea why.  I know Photo Flo has a shelf life that is
rather indeterminate for me.  Sometimes if I mix it a little too strong
I get marks; if it is a little too old I get marks.  It all seems
arbitrary to me.  Anyway I learned early on in my career to just dip the
first two fingers of one hand in the Photo Flo and strip the excess off
between those fingers rather than a sponge or rag.  Works for me. Please
share with us the results of your tests.

Steve Homer wrote:

> Thanks for the several helpful comments about my
> stained or flawed negatives. (URL is
> http://members.cruzio.com/~shomer/stain.jpg )
>
> Several of you suggested that they might be drying
> marks. I do use Photo-Flo, mixed in distilled water; is
> it possible to get such large drying marks from that
> solution? I do not wipe the negatives with a sponge or
> squeegie; I shake the reel, and then the film hangs to
> dry at room temperature.
>
> Don Roberts asked about the orientation of the marks:
> the marks are either in line with the length of the
> film, or diagonal to it: never across the narrow width
> of the 6cm x7cm negative. So that much is consistent
> with drying marks.
>
> Does it make sense that I would see drying marks on the
> 70mm infrared film, but not on TMAX 120 processed in
> the same batch of chemistry and hung to dry in the same
> location?
>
> My Photo-Flo solution is about 60-65 degrees F (warmer
> than my wash water, but colder than the processing
> temperature), but until this Winter my Photo-Flo
> solution was always at about 70-72 degrees F. So that's
> a change in my process that I hadn't paid attention to.
> Is a cold wetting agent more likely to spot?
>
> The other suggestion was static marks. I probably wind
> it faster while I am bulk loading it in the darkroom
> than when I advance the film in the camera, but I never
> see static discharges while bulk loading.
>
> Here's how I plan to test the two theories. For the
> drying marks, I will try a distilled water rinse before
> the Photo-Flo rinse, and mix the Photo-Flo at a lower
> concentration. I'll also expect the marks to be worst
> at the bottom of the strips hanging to dry (where drips
> collect). For the static, I can try to wind the film
> more slowly in the studio, and perhaps try winding it
> with the back open in the darkroom to see if I can
> observe any static discharge. Can anyone suggest a more
> reliable test, or see problems in these tests?
>
> Thanks again for all the helpful comments.
> ____________________________________________________
> Steve Homer    shomer@xxxxxxxxxx   Santa Cruz, CA  USA
> Technical Documentation Services   831-251-8516 (cell)
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--
============================================================
   Don Roberts * Bittersweet Productions * Iowa City, IA
         *                         *
  And the Devil whispered behind the leaves, "It's pretty,
  but is it Art?".   --  Rudyard Kipling
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