Reel scum

[Wayde Allen <allen@xxxxxxxxxxxxxxxx>]

On Tue, 10 Jun 1997, Ken Sinclair wrote:

> OK. One of the notorious problems of plastic reels is that there is a
> tendancy for a "build-up" or deposit of getalin on the inside tracks of the
> reels. This should be removed on a regular basis with a dilute chlorine
> bleach. 

Yes that is true.  Wouldn't metal reels have the same problem?

> The problems may be compounded over time when the reel is not properly
> washed after the final wash of the last roll of film and the surfactant in
> the final rinse is absorbed by this "scum". Basically, the activity of the
> developer on the next roll of fim is a bit more "vigourous" at or near the
> area where the film is in contact with the reel.

Do you know more about the mechanism for this?  My first inclination is
that the scum would tend to prevent fresh developer from reaching the film
in this region, but this would have the opposite affect from what you
state.  The surfacant absorbed in the scum may be the answer.  Does adding
a wetting agent to a developer increase its activity?  Perhaps this
increases the penetration of the developing agent into the gelatin? 
Anyone know? 

Interesting!!!  I probably need to clean some of my tanks.

- - Wayde
  (allen@xxxxxxxxxxxxxxxx)

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