FotoDave@aol.com
Thu, 03 Jun 1999 14:41:52 -0400 (EDT)
> What isn't clear
> to me is how you could dry a gelatin Sol without it forming a gel?
I believe in Collotype, they use a heated oven so that the emulsion would dry
without forming a gel, but that's a different process where reticulation is
purposedly wanted.
> Yes, and I believe that the primary reason for the addition of sugar is to
> help the gelatin retain moisture. I simply have gotten curious though,
> since it seems that too much sugar could cause problems as well.
>
> > I've found (again, to my
> > own satisfaction) that drying tissue in a controlled humidity (70-75%
> seems
> > to work best),
The old formula uses syrup or honey, which is somehow soft and sticky.
Glycerine helps the emulsion to absorb water from the atmosphere (see the
"Studio Collotyp" by Kirby or Kibby? It is mentioned there that when
glycerine+water is used to soak the matrix, the matrix doesn't need to be
resoak because it automatically absorb the water from the air, so it is clear
in that case the gelatin matrix doesn't dry out, at least not during the
length of printing), so my "guess" or "theory" or "model" is that when the
right proportion of glycerine is used, the gel does not dry to as dry as if
no glycerine is used. That makes the honey or syrup somewhat syrupy, so the
emulsion is soft.
But that's just my attempt to explain the thing. It absolutely does not mean
that it is right (or wrong). I hope the discussion will go on including the
pointing out of the error in my explanation so that we can have better
understanding of the material.
(I seem to overexplain myself, but in the past I found that some people don't
like this type of discussion and feel that I am trying to claim that I am
right when I am wrong or things like that). :)
Dave S
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