Stock Paint:Gum Solutions?

[Loris Medici <mail@loris.medici.name>]

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.