Chris,
My mix is 3 part of gum/pigment, 3 parts of water, 1 part of 30% ammonium dichromate. All measured by volume. I do not use dry dichromate sals in my gum mixes. Exposure about 1-2 minutes in a bank of BL tubes.
Marek
> Date: Thu, 3 Jan 2008 07:23:24 -0700
> From: zphoto@montana.net
> Subject: Re: gum mixes
> To: alt-photo-process-l@usask.ca
>
> 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
>
>
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