Re: Odd marks on negative -- help needed

[Steve Homer <shomer@xxxxxxxxxx>]

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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