>I really wasn't planning to get into Terry and Pete's latest discussion, but
from my (admittedly) imperfect understanding of dichromated colloids I might
be able to clear something up. Peter Marshall has already quite clearly
explained what's going on in dichromated colloids only a month or two ago.
If the rest of us can bear it again, this is what I understand is happening:<
Hello Philip
Your intervention into our discussion is most welcome and timely
Unfortunately I missed Peter Marshells clear explanation. What started out
as a simple discussion relating to pigment stain, is now developing into an
investigative study of the dichromated colloid imaging system, relating
specifically to the direct carbon processes, of in my case gum Arabic,
gloy[PVA], and Fotempera [whole egg ] these three colliods work in a very
similar manner.
I am not contradicting Terry who would dare ;-) [ this is not a flame it is
just that we Brits love taking the gloves off when we are together ] but
what I'm saying is that the mechanism of stain removal. Relies not so much
on the stain being washed out of the colloidal layer , but that the stain
changes its chemical character, when the various clearing agents are
applied including the water soaks , which has the effect of making the
image less visible, but in my opinion the chrome chemical is still present.
I am at the moment conducting a series of tests to establish the physical
parameters of the Dichromate stain .Employing only the colloid with no
pigment present to cloud the issue. Starting of with my plastic base
Synteape then moving on to other papers to compare differences.
The colloid mixes will be equal parts
of colloid, to sat sol Ammonium Dichromate, and the gum Arabic will be a
50% mix , the gloy and whole egg as they come.
Perhaps you would like to take part,as you seem to have an interest, and I
need somone to cross check my data, in fact anybody else reading this
e;mail would be most wellcome to take part.
pete.