Re: gum mixes

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

Dear Christina,

I use lump gum arabic (labelled Kordofan No.1). Add 70 g gum to 200 ml
deionised water (probably no point at all in using deionised, given the bits
and pieces in the gum). Leave to dissolve overnight, with occasional shake.
Resulting bitty liquid filtered through 2 layers of disposable synthetic
household cloth (often called J-cloths in UK) to leave clear, very pale
straw-coloured gum solution. Add a few drops of formalin as preservative.
Gum still in good condition after a year. I seem to find this gum much
easier to print with than lithographer's gum, but haven't done any objective
tests to see why (or whether) this is so.

Immediately before coating, mix 5 ml gum with small blob (very scientific)
of tube pigment, then add 5 ml saturated potassium dichromate. Enough to
coat 5-6 7x9 inch prints using a hake brush. Occasionally use powder
pigments. I don't do enough printing to warrant keeping stock gum-pigment
solutions, though the advantages are obvious.

Happy Christmas!

Henry


On 23/12/07 18:18, "Christina Z. Anderson" <zphoto@montana.net> wrote:

> Dear all,
> 
> I'm finishing my section on gum thicknesses, and was wondering a question or
> two of all one-time to inveterate gum printers:
> 
> 1.  How many of you are using premixed gum?
> 2.  If  not and you are mixing your own, what dilution are you mixing it at
> exactly--weight of gum into what volume of water, for instance? If it is
> 300g in a TOTAL volume of 1 liter, or 300g PLUS one liter please
> differentiate clearly. If, mixing more than one solution, also state.  If
> not using gum/pigment 1:1 sensitizer at time of use please note.
> 
> Any other practices, I'd love to hear--e.g. using a hydrometer or some such
> thing. Or if you use dry gum at time of use in your sensitized mix and do
> not premix a gum solution.  Stuff like that.  I've got the timeline almost
> finished on gum dilutions from beginning til now and I want the "now" as in
> 2007.  Hopefully this isn't too pointless, misleading, and confusing!
> Chris
> 
> __________________
> Christina Z. Anderson
> Assistant Professor
> Photo Option Coordinator
> Montana State University
> Box 173350
> Bozeman, MT  59717
> 406.994.6219
> CZAphotography.com
> 
>