Re: grooves on tubes RE: jobo help


Wayde Allen (wallen@boulder.nist.gov)
Fri, 22 Oct 1999 16:31:32 -0600 (MDT)


On Fri, 22 Oct 1999, Richard Knoppow wrote:

> Actually the backing is not removed, only decolorized. In think the only
> backing which is physically removed is the Rem-Jet baking on some Kodak
> motion picture color films and on Kodachrome. You can experiment with a
> scrap of film. You will find that either developer or fixer will decolorize
> the anti-halation layer but that nothing is removed from the film.
> In some cases a plain water soak will decolorize it.
> Some color films have an anti-halation layer under the emulsion.

I have a sneaking suspicion that we are getting close to discussing
semantics here. At any rate, the color from the antihalation
coating needs to be removed. My impression is that this is basically a
water soluble dye that is washed out of either a layer in the emulsion or
a coating on the back of the film. Indeed when I'm developing film my
prewash water and developer tend to become discolored with this dye that
evidently is removed from the film. Whether or not this means that the
substrate carrying the dye is removed I don't know.

What I'm curious about, is whether or not the film processing causes the
dye to become less soluble, or if somehow the developer contains something
that removes, washes, or decolorizes this dye better?

Another way of formulating the question would be to ask: what is the
mechanism for the decolorization you talk about?

- Wayde
  (wallen@boulder.nist.gov)



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