[filmscanners] Re: Topic: "Halo" Effect

["Arthur Entlich" <artistic-1@shaw.ca>]

I haven't worked with anti-halation films myself, but back when I ran a
color lab we'd occasional get some which we had to watch for (it was
mainly respooled motion picture film, and we used to give the
photographers who brought in bulk spooled film the 3rd degree before
we'd process).  Unfortunately, occasionally this film would still sneak
in. It had an anti-halation coating which was not soluble in photo
chemicals, but did, none the less, come off at color chemical processing
temperatures, making an absolute mess of the chemistry, leaving strands
of black glop that would adhere to other films and the processing
machinery, so we would have to tear down the whole system and scrub it
clean, and then replace the chemistry.  It was a very costly and time
consuming ordeal, and it also sometimes required we rewash some other
clients films that happened to be in the tanks at the time this occurred
to get the residue off.  It was NOT a happy day in the lab when this
would occur.

Back then, apparently, the proper process for this film was that it was
wet down and then the anti-halation layer was buffed off the film
mechanically, then the film was rinsed and only after that it was put
through standard development, to protect the other film and chemistry.
The cine labs that typically processed this film were of course set up
thusly.  We weren't.

Certainly possible newer films use a fully soluble coating which comes
off in the chemistry with little or no side effects to the other films
and equipment.  I left the color lab in the early 1980's.

Art

Austin Franklin wrote:

>>..."anti halation" layer, which is a black coating
>>on the back which has to be removed mechanically...
>>
>
> Arthur,
>
>>From my experience, the anti-halation layer can be different colors, not
> only black.  I'm not quite sure what you mean by "removed mechanically", but
> for the films I use, no mechanical process is involved to remove the
> anti-halation coating, if I understand what you mean by "mechanical".
>
> If you pre-soak, on discharge, you'll see the wash water be dark blue/black
> and mucky (or what ever color used), and this would be the anti-halation
> layer and/or the sensitizing dye...depending on what is used on that film.
> If you don't pre-soak it's removed in the developer.
>
> When I first saw the water from the films with these dyes (I believe Neopan
> 1600 is the one that comes to mind?), it came as a bit of a surprise.
>
> Austin
>
>
>


----------------------------------------------------------------------------------------
Unsubscribe by mail to listserver@halftone.co.uk, with 'unsubscribe 
filmscanners'
or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or 
body