tonal inversion and pigment loads

A couple of points:

Why I think Mike Ware and Judy are right to link exposure in with the
variables of why tonal inversion--the steps on the step wedge that invert,
do so STEPPED--they go from light to dark just as they do from dark to
light. If it were totally a factor of pigment stain, there would not be
steps.

As far as pigment load, I thought I would share my method that has taken me
through 1000 (no s--t) prints: I mix 1 tube of 14/15ml watercolor paint
(not pigment powder) into 45 ml gum--this makes 60ml solution. At time of
use, I use this stock solution in this ratio:

1 tsp stock pigmented gum:1 tsp plain gum:1 tsp water: 1 tsp saturated am
di.

In essence, this is a 1gum:1di formula from days of old, it's just that I
weaken my am di to half strength, and I weaken my stock pigment to half
strength.

I then, if a color is weak, double the amount of stock pigment in the
equation and cut out the plain gum.

If the color is strong, I half the stock pigment in the equation and add
more plain gum.

Most of the time I use scant and overflowing teaspoons to do the same
adjustment.

For instance, with raw sienna, I would use a full 2 tsp of stock to the am
di. With q. magenta I use maybe as little as 1/2 tsp stock and 1 1/2 tsp of
plain gum to the di, but this depends on brand.

This way, I can easily keep track of and vary my saturation to the pigment
brand at hand, and know what I did, as opposed to measuring out worms or
grams. It is a truly user friendly "dump and pour" method. I know how much
saturation I need by the first time i have printed a print, but I also have
the ability to choose to do a blandly pigmented gum as well as a deeply
saturated one, AND the pigment is well mixed into the gum already so no
streaking.

I never need to go above the doubling of the stock pigment (the equivalent
of 1/2 tsp tube watercolor pigment itself in 4 tsp of mix--this is plenty
dark).

Hope this makes sense and is of use to someone out there! I am so excited
because I get to teach this to 15 eager students this semester all chomping
at the bit.
Chris
Received on Thu Jan 12 15:33:02 2006