Air Bubbles

[Jim Henderson <74023.723@xxxxxxxxxxxxxx>]

The problem with air bubbles may be related to the amount of dissolved clorine
in the tap water.  Studies in Portland, Oregon by a photographer who worked for
the public works revealed that the bubble problem was most troubling at the peak
of the summer swimming season, in September, and in October.  Coincidentally,
more dissolved chlorine was found in the water system during the summer months,
because more chlorine must be added as temperatures elevate; when the
temperatures drop overnight, the result is a high chlorine content.  In the
fall, leaves and debris enter the water system and must receive more treatment,
which again elevates dissolved chlorine in the tap water.

The result of all this may be that chlorine gas is the culprit.  An un-named
Technical Rep from a well known film manufacturer told me that people had
experienced similar problems with Estar-based film emulsions and the cause was
air bells adhering to the emulsion side of the film.  Gas is released from the
developer solutions with high chlorine content and adheres to the film.  His
recommendation was to use de-ionized water when mixing ALL developers.  No
chlorine, no air bubbles on the film...

External air bells may be recognised by their smooth, rounded edges; whereas,
gas bubble that rupture from within the emulsion (caused by an overly strong
acid stop bath) are ragged.

Jim Henderson
Applied Scientific Photography


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Topic No. 20