RE: gum mixes

[Robert <rc3@flash.net>]

Hi Chris,

I have been away from my computer and just reading your post. I wish you and
every one on the list a Happy New Year. Like you 

I mix a full tube of paint with About 50 ml(depends on pigment sometimes use
100ml) premix gum from BS. Then I use 6ml premixed paint to 10 mil gum. My
exposures run from 5 to 8 min on a NuArc unit.

Best regards,
Robert Cockrell


-----Original Message-----
From: Christina Z. Anderson [mailto:zphoto@montana.net] 
Sent: Thursday, January 03, 2008 6:23 AM
To: alt-photo-process-l@usask.ca
Subject: Re: gum mixes

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.
Chris
  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
406.994.6219
CZAphotography.com