From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 06/27/02-01:04:54 AM Z
At 10:39 PM 06/26/2002 -0700, you wrote:
>What causes negatives to get little white "holes" or specks in the emulsion?
>I heard that you can prevent this by using water instead of stop, but I
>always use water and I get them anyway.
>
>--shannon
>
>
Pin holes which are actual disruptions in the emulsion are very unusual.
Carbonate containing developers can cause some effervescing when the film
or print is put into the stop bath but this does not commonly result in
actual disruption of the emulsion. In any case, few commercially packaged
or widely used film developers use carbonates for accelerators. Most use
borax or a metaborate, neither of which produces gas in combination with
acid. Nor does the hydroxide in Rodinal.
Check the clear spots on the negatives with a strong magnifying glass.
Look at the surface was well as looking by transmission. Real pin holes
usually are visible as small deperssions or pits on the surface.
Its more likely for clear spots to be formed by particulate matter in the
developer settling on the surface of the film and interfering with its
development.
In some areas water has a lot of particulate matter in it and must be
filtered for photographic use. Its also possible to have particals of
undissolved material in developers. Filer the developer to get rid of them.
In fact, its good practice to filter all solutions before use and those
which are re-used when they are returned to storage.
Clear spots can also be caused by dust in the camera. This is a plague
for sheet film but can also occur with 35mm and roll film.
Loading sheet film without dust getting on it requires some diligence.
Holders should be vaccumed out and wiped down with a damp cloth. Changing
bag interiors should get the same treatment. The interior of the camera
should be vacuumed out and if possible wiped with a damp cloth. You will
still get occasional dust no matter what you do.
---- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com
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