U of S | Mailing List Archive | alt-photo-process-l | RE: Seeking Information on 2 problems with Gum process

RE: Seeking Information on 2 problems with Gum process

Hi Clair,
I would like to suggest a standard method of making tricolor gum, knowing very well that everybody disagrees on it and rightly so. Gum is about constant experimentation, changes and variation that makes it so appealing. On the other hand if you would start with a standard recipe that produces decent prints, the less frusrtation and more joy in experimenting you will have. I would agree with CHris that quinacridone rose and thalo blue (green shade from Daniel SMith) are best to try as primary colors. I would suggest Hansa Yellow Medium, PY 97. I buy mine from Daniel Smith and recommend that source. To make it even easier and more repeatable I suggest mixing stock solutions. One tube of watercolor plus 150 cc of gum for blue and yellow and slightly less gum, say 120 cc gum for magenta. Solution keeps for a long time (2+ years). Py97 is not very transparent so the order of printing should be cyan, yellow, magenta. You will discover the taste for other yellows quickly
To use shake well, pour 10 cc of pigment stock, 5 cc of 30% ammonium dichromate and 10 cc of water. Use about 4 cc of that mix to cover 8x10 inch with 1" border (10x12).
That should get you started.

> Date: Tue, 29 Apr 2008 05:12:02 -0400
> From: cadunn@vt2000.com
> Subject: Seeking Information on 2 problems with Gum process
> To: alt-photo-process-l@usask.ca
> Hi --
> I was warned before I joined this list that it was NOT a place
> for newbie questions. And I have refrained assiduously and have
> spent hours searching for my answers elsewhere. Fortunately I now
> have a ready source of answers for most questions--having spent
> almost my last nickels on Christopher James' book and the run of
> Judy's PFP.
> BUT, there are two areas where I need help and no one seems to
> mention it, no matter how meticulously they outline each process.
> (I'm working small -- 4.5 x 7 and using Arches Hot Press 140lb.
> because I like the smooth texture and finer detail possible with
> it, which I have achieved quite well with Cyanotypes.)
> For any process where you wish to coat and expose the same piece
> of paper multiple times, what do people do with the severely
> uneven paper between exposures? I have preshrunk it and dried and
> ironed it before doing anything to it. But, once it is (perhaps
> sized depending on the process), coated, exposed, washed, and
> dried, it reverts to hills and valleys. And yes the contact frame
> flattens out everything, and the large objects in the image
> appear nicely, but registration problems ensue in finely detailed
> areas. I need help!
> My last nickels are for pigment. I've read much about pigments
> recently and assumed that folks would have made lists (as they
> have for just about everything under the sun, e.g., paper,
> emulsion proportions, etc.) Not so -- or at least I haven't found
> one. I found info on Lamp Black vs. Ivory Black, but so far
> nothing on other colors.)
> Breaking the image up into CMY or CMYK indicates the use of 3 or
> 4 pigments respectively. What do people use for the best
> non-staining results? (I can tell you that Holbein Ultramarine
> Deep Watercolor gives excellent blue snow on sized paper! lol)
> I realize that folks, and I will be one of these, like to shift
> things around depending on the image and the effect they are
> after, but for your basic palette-- what works??
> I figure that folks expert in various processes have their
> arsenals of pigments and would know what works. Because I can't
> afford to experiment right now with things I have to buy, I'm
> asking for help.
> And thank you very much in advance.
> Clair

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