Loris,
I found that using stock solutions is the way to go to get consistency. As Chris noted modern organic pigments do not separate and stay suspended in gum solutions forever, just a little shake and you are ready to go.
My thalo blue stock is 15 ml tube (Daniel Smith) to 150 cc of gum. Magenta, which is quinacridone rose (PV19) is 1 tube to 120 cc of gum, my standard yellow now is PY150 and it is 1 tube to 300 cc of gum. I have to say I did not use PY151 that you mention and Daniel Smith does not carry it. Most of other colors that I use require about 150cc of gum for proper balance. ANother color that is very strong is PR254 (Ferrari red), I have a stock of 1 tube to 300 cc. If you do not want to mix that much stock you can mix it with 150 and at 1 part of gum for printing. I add 0.3 to 0.5 part of saturated ammonium dichromate to 1 part of gum/pigment. I found no compelling reason to add more and then wash it down the sink. I add 1 part of water for 1 part of gum. This dictates the thickness of gum in a finished print and would change somewhat depending on paper absorbency. Lastly, I measure my gum solution and pour the exact amount for a given negative size, for eample 8.5x11 requires 3cc of sensitizer for my paper (Fabriano Artistico).
If you have 10 prints to do just mix a batch and measure a predetermined amount for each print. My workflow is to do a single colour is a session, which is 2-3 hours and allows for 8 to 12 prints. So tonight is magenta night.
You do have very similar cyan and magents dilutions and as I noted I did not ever use your yellow. I seems that your concentrations would be about 2x as much as I use and that would give you very strong and saturated prints, somewhat difficult to balance midtones, higlight and shadows in my opinion. AT these concentrations I run into some stain issued. I prefer to work in somewhat weaker layers and add pggment in more then 3 layers, on the average say about 5. You can always improve a prints that is too light with another layer or two or three.
You are a fast learner and progressing well.
Marek
> Date: Wed, 22 Oct 2008 08:13:39 -0600
> From: zphoto@montana.net
> Subject: Re: Stock Paint:Gum Solutions?
> To: alt-photo-process-l@usask.ca
>
> OK this is it--one last email before I get on the road. Have to teach a gum
> workshop in Missoula MT 200 mi away and I have to have my hubby drive me
> there because I can't drive with a knee brace. He has to sit in a town for
> two days entertaining himself so you can imagine he's one happy camper.
>
> I mix all pigments 15ml tube in a total volume of 60ml because that is the
> size nalgene bottles I have.
>
> At time of use I cut my pigments with plain gum--thalo gets cut as much as
> 1+5, yellow maybe 1+2, magenta maybe 1+3, depending.
>
> Stock solutions are a cinch to use, and I only have problems with the heavy
> pigments which settle and separate into a sludge on the bottom--nickel
> titanate, cerulean, cadmiums. Since I no longer use these colors, mixing
> stock is not a problem for me as far as separation is concerned.
>
> I think your thalo may be too concentrated, but I notice a progression of
> yellow-magenta-thalo which I also do as far as strength.
>
> One more thing--at time of use I may decide to do an undersaturated print,
> too, in which case I cut all pigments way more.
>
> There are several list members who have this down to a real
> exactitude--Marek, Dave Rose used to, and they'll tell you exactly how much.
> OH, you could do a search for Dave Rose's posts a few years back but he did
> use powdered pigment.
> Chris
> __________________
>
> Christina Z. Anderson
> http://christinaZanderson.com/
> __________________
> ----- Original Message -----
> From: "Loris Medici" <mail@loris.medici.name>
> To: <alt-photo-process-l@usask.ca>
> Sent: Wednesday, October 22, 2008 7:56 AM
> Subject: Stock Paint:Gum Solutions?
>
>
> >I was reading handprint.com's "The Secret of Glowing Color" page, which
> > contains very good and interesting information, especially in the section
> > "Not Black, Not Light".
> > (http://www.handprint.com/HP/WCL/tech16.html)
> >
> > I slowly feel the need of making stock paint:gum solutions, in order to
> > get more consistency and ease of use. Mixing small amounts of paint:gum
> > solutions is hard to do consistently, especially with strong colorants and
> > small image sizes. (Because squeezing small amnt. from the tube is not
> > easy!)
> >
> > I decided to make stock solutions as listed below:
> >
> > Yellow PY151 1:2 (1:4 final) -> 15ml paint + 30ml gum
> > Magenta PV19 1:3 (1:6 final) -> 15ml paint + 45ml gum
> > Cyan PB15:3 1:4 (1:8 final) -> 15ml paint + 60ml gum
> >
> > Since the stock paint:gum is further diluted 1:1 with dichromate, the
> > actual paint dilution in the coating solution will be exactly the half of
> > what it is in the paint:gum solution. (See inside parenthesis.)
> >
> > This question goes to users of stock paint:gum solutions (such as
> > Katharine and Christina):
> >
> > Do you find above figures close to ideal? What is your experience with
> > those pigments? Anything to pay attention / be careful about using
> > paint:gum stock solutions?
> >
> > Thanks in advance,
> > Loris.
> >
> >
>
>
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