Re: gum mixes

[Henry Rattle <henry.rattle@ntlworld.com>]

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.

Best 

Henry


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.
> 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
> 
>