RE: Little white spots and static electricity

["Jason Revell (in5)" <jason.revell@xxxxxxxxx>]

I agree that this is a interesting theory but I must confess I remain
unconvinced.

We use a lot of 5x4 HIE film here at my work, I very rarely get the
pinholes
but I sometimes do.  When this has happened it has never been from a
new box of film only from older film that has been open for a month or
two.
I am also unsure of how much static charge could be built up on one side
of a darkslide and not on the other.

The last time I had the 'pinholes' I had a look at them under a
microscope
at about x40 and x100 mag.  and you can very clearly see that were the
'pinhole' is the emulsion is not level.  You get a definite dip in the
level
of the image, lower I believe than areas where no image has recorded.

I have also not yet ever had them on a roll of 35mm even when using
my cameras with autowind which would surely have a good chance
of building up static as opposed to sheet film?

I still remain skeptical about the pinholes and feel they are either a
manufacturing fault were the emulsion has either not been coated
fully or has begun to slightly delaminate from the base. or they could
be caused by some form of 'mold' growth as they, under the microscope,
look like the circles of mold that grow, i.e. with a strong center and
slightly
softer/weaker around the edges.

These are just my feelings about the pinholes, but I am sure that we
shall
never really know what causes them.  Once I even got them on a sheet
that had got fogged while I was testing one of the darkrooms, all it had
done was come out of it's packet, sit on a sheet of soft paper for
10 minutes and then straight into a tank of Dev.

Jason Revell
jason.revell@xxxxxxxxx


 ----------
From: Peter Badcock
To: infrared
Subject: Little white spots and static electricity
Date: Thursday, 09 April, 1998 6:07



This is an interesting theory Angela.  Static electricity can be
generated by
friction between two bodies.  Eg. the Film(polyester) and the changing
bag.  Or
the film and the (plastic)take-up spool.  And the amount will depend on
a few
factors too, such as : how humid the surrounding environment is
(ironically DRY
is worse than wet), what the two bodies are made from, and how fast they
are
rubbed together.

A static electricity discharge, onto the film, even too small to hear
could
easily do damage to the film's surface.  If you need to know how much
the
environment may be prone to static , take off a sweater inside in a room
with
all the lights off, and if it's dry enough then watch/hear those sparks
fly.

what do others think?

regards
Peter B

______________________________ Reply Separator
_________________________________
Subject: Re: Sprocket shadows & little white spots
Author:  <infrared@xxxxx> at INTERNET
Date:    09/4/98 4:17


I have since read something in "Darkroom Dynamics" that talks about
that same effect from static electricity.  Has anyone had any
experience with static electricity and infrared?  I thought that would
only be a problem in cold weather with a motor drive, but . . .

Angela
aeophoto@xxxxxxxxxxx


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