> At 12:28 AM 7/7/97 -0400, you wrote:
> >If I followed your train of thought correctly then I agree that a good
> >deal of smoke and mirrors has been thrown about to hide a simple
> Well.... I didn't want to put it quite that directly, but now that you have
> --- yes.
> >I think the real underlying "secret" to the Fresson process lies in
> >formulas which are a mixture of gum and gelatin. The proportions change
> >the characteristics of each layer where the gum adds to the adhesive
> >quality and the gelatin the cohesive quality. In addition this
> >gum/gelatin ratio affects grain, tonal transition and the ultimate
> >maximum shadow density.
> Ultimately I think you are right and the answer lies in the "mechanical"
> structure of the coating as opposed to the "chemical", though the two are
> intertwined of course. My theory is that the structure allows for some
> tunnels from the surface down to the paper level which allows water in to
> dissolve the pigment bearing colloid from the soft bottom layer. The
> tunnels allow the water in and the pigment and colloid out. The hard top
> "roof" layer is flexible enough to collapse without breaking. This may or
> may not be the "Fresson principle", and who cares what it is so long as it
> makes pretty pictures. This seems like a logical principle from which to work.
Sounds like PhD material to me . . . all kidding aside you may be correct.
As to the physical vs chemical nature of the materials . . . don't forget
we are dealing with colloids, very peculiar and interesting stuff. I
personaly believe it has to do with the mixture of gum and gelatin.
Remember that they are not really compatible but I think that they appear
to be mixed only because one of the two is encapsulating the other. I
think as they dry they separate again forming the reticulation pattern
Nadeau talks about and which can be seen in my papers and raw Fresson
samples I now have from Bill Foster.
> I don't know whether the 4-color is a single coat system or not but if it
> is then the machine is probably using using as Lumiere plate principle and
> putting down dots in that fashion.
Based upon Nadeau's books, each primary color is printed on top of each
other as in 4 color carbon and/or gum.
Columbus, Ohio, USA