Re: Gum hardening -- top down?

> In the past, the "proof" that has been offered here for hardening at the
> paper surface is no proof at all but Mike Ware's speculation that the
> dichromate may be strongly absorbed to the paper; he thinks it may
> move down through the layer and congregate at the paper surface, and if
> this is so, that is where hardening would take place, because that is
> where the bulk of the dichromate would be found. But it's just a
> hypothesis, and he has offered no evidence that I know of to support
> this hypothesis.

Now THIS is fascinating, Katharine, because I have noticed, when brushing on
a layer of magenta, for instance, that the swathe of my brush moves fast
enough to show that underneath the swathe of magenta gum there is a
separated yellow swathe of dichromate. That sounds like a really odd
description, but I always felt that the dichromate "fell" to the bottom of
the layer and "hit" the paper first.

I thought that maybe I had not mixed the dichromate into the gum/pigment
mixture well enough, but that doesn't seem to be the reason and I continue
to observe this phenomenon.

Whether this leads to a conclusion of top or bottom hardening, I wouldn't
even begin to surmise.

i also notice that magenta, whether as a first layer or as a last, always
"fisheyes" the most, as if it is an oilier pigment or something. Whether
that, too, has an effect on the seeming separation of dichromate from
pigmented gum, I too, have no clue.
Chris
Received on Wed Apr 5 08:21:35 2006