See http://www.bostick-sullivan.com/gum.htm -- [Yo Jeff!]
I have always been intrigued by Walter Zimmerman's Method published in The
Photo-Miniature No. 113, October 1910. I checked the old boy out and he
seems to have done some stunning work though I have never found or have
seen an originals of his. I believe from his history and critical reviews
at the time he qualifies as an "expert." Often wondered if he is in any way
related to Bob Dylan.
I tinkered with his method during my later gum period. I used his blotter
method of development and just got an awful mess, but I attribute that to
the the fact that my blotter paper was different from his. Mine just
disentigrated. However, his gum ratio idea seemed to have worked. I moved
on to platinum printing and my gum explorations died, but I'd like to find
time to go back to it.
Says Zimmerman:
<<
The principle is this: Use just enough of the gum to hold the pigment
together, and no more. It is not a question as to a multiplicity of opinion
regarding the correctness of proportion; the quality of the gum is fixed as
just stated; that of the bichromate is, to some extent, a matter of
preference. The old method of which I advise you to discard at once, is to
take so much gum solution and so much bichromate solution, mix, and the
pour so much of the combination into so much pigment. As the "so much" was
a variable quantity according to the instructor, the more one was
instructed the less he knew, all the instructions probably being wrong.....
Carrying out the principle stated, the method of mixing -- and an extremely
easy and simple one-- is this: take of the pigment, from tube or powder,
enough to heap on the point of a penknife-blade, more or less, according to
the work to be done. Then pour in, of the thick gum solution, a little more
than the bulk of the pigment being used. [!] I know very well what the
advanced worker will say to this direction; but let him be good enough to
try for himself without prejudice. With a pestle, work the together the
pigment and the gum, in the mortar; if the gum takes up -- that is, of
course, in suspension -- all of the pigment, you are ready for the next
step; if it does not, add a few drops of gum and repeat grinding. With all
of the pigment held in suspension by the gum solution, pour in four to six
times as much of the saturated bichromate of potash solution. Mix these
thoroughly, with the mortar, and your pigment is ready.
{He recommends a mix of two parts by weight of gum to three of water.]
>>
Just thought I'd pass this along to the experimentally inclined.
--Dick Sullivan
Bostick & Sullivan
PO Box 16639, Santa Fe
NM 87506
505-474-0890 FAX 505-474-2857
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