U of S | Mailing List Archive | alt-photo-process-l | Re: gum mixes

Re: gum mixes

Thanks, y'all, for clarifying--whew! I was really wondering there for a moment.

And thanks for the rest of the responses, too. Keith--I'm describing yours as "loosey-goosey" :) or the "intuitive" method of gum printing--going by feel.

Any of you do the heavy gum mix/lighter exposure/runny impressionistic one coat French method?

----- Original Message ----- From: "Henry Rattle" <henry.rattle@ntlworld.com>
To: <alt-photo-process-l@usask.ca>
Sent: Thursday, January 03, 2008 9:54 AM
Subject: Re: gum mixes

Hi Christina,

For my method (8) the gum mix is right but then it's 5ml gum mixed with
small blob of pigment (using flexible palette knife on a small tea-plate)
and then 5 ml potassium dichromate added. No additional water. The resulting
10 ml is enough to coat 5-6 sheets of sized paper for about 7x9 inches
image, using a hake brush.



On 3/1/08 14:23, "Christina Z. Anderson" <zphoto@montana.net> wrote:

Dear all,
So this is what I have so far--only 10 gum printers on the list apparently
The range of practice of gum never ceases to amaze me. In historical times
it was 10% gum to 100% gum (the latter was mixed 1 gum powder to 1 water--I
know, it is not technically a 100% solution but that was what they termed it
in those days--in other words, a 40% solution was 40g gum PLUS 100ml water,
not in a total combined volume of 100ml.
Some questions: Marek, do you use dry am di at time of use? Henry and
David, at time of use you mix essentially a half strength potassium
dichromate and am I correct with your 1 di: 1 water: 10 (!) gum? How long
are your exposures and are they in the sun? Guido, same thing--do you use
that little potassium dichromate in your mix--essentially 1-5 parts gum to
only 1/2 part pot di? If I have anyone's info wrong, let me know.
1.. Sam Wang 1+2 powdered and at time of use 1:1 with dry am di
2.. John Brewer 3+10 powdered, preserved with 15ml formalin per liter, at
time of use 1:1 mix, changing this ratio for highlights and shadows
3.. Kees Brandenburg 3+10 LUMP which he says is 14 baume and at time of
use 1:1
4.. Marek Matusz premixed gum, stock pigment mixes of 1 tube pigment in
120ml gum and at time of use 3pt gum/pigment to 3 pt water to 1 part AMT
5.. Joe Smigiel is premixed 14 baume and at time of use 1:1 pot di, tube
pigments, sometimes powder pigments, sometimes mica or interference pigments
6.. Bill Mull is premixed gum and stock pigment made with gouache at 6
gum: 1 gouache and at time of use 1:1 pot di and one coat gums made with
paper negs
7.. Hamish premixed gum and stock pigment solutions and at time of use
1:1, but sometimes 1:2
8.. Henry Rattle 70 to 200 Kordofan No. 1 LUMPS with few drops formalin
and at time of use 1 di: 1 water: 10 gum
9.. Guido Ceuppens 200g to 850 water with 5gr sodium benzoate with stock
pigments of 1 g watercolor tube: 6ml gum and at time of use 1 part stock:0-4
parts gum:0.5 pot di
10.. David Hatton 500g + 1 liter with 10 drops 100% thymol and at time of
use 1 pot di:1 water:10ml gum with varying amounts of pigment depending on
layer, color
Christina Z. Anderson
Assistant Professor
Photo Option Coordinator
Montana State University
Box 173350
Bozeman, MT 59717

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