Re: Why multiple exposure (was Re: (Gum) Tonal scale)

On Dec 2, 2005, at 1:47 PM, Katharine Thayer wrote:

>
> On Dec 1, 2005, at 12:34 AM, Loris Medici wrote:
>
>> BTW, what I trying to achieve is to standardize my pigment + gum +
>> dichromate emulsion mixes and exposure time for each color, so that
>> they
>> all give me the same number of steps. Only after managing this I will
>> start to build curves and attempt to make tricolors. (Not that I feel
>> an
>> urge to do tricolor gums - just for its fun...) What do you think
>> about
>> this strategy?
>
> I think Chris already suggested not using this approach for other
> reasons, but I would discourage it because you will find that the
> different pigments will print a different number of steps and there's
> just not a lot you can do about it. I don't think your yellow,
> especially since it's PY154, a light-valued azo, will print as many
> steps as your pthalo. I don't think you would want to deliberately
> shorten the range of the pthalo to match the yellow, just for
> calibration's sake, would you? So I think this approach, since you
> asked, wouldn't be a productive approach to take.

I've been told recently that I don't spell things out clearly enough
for beginning gum printers to understand, and perhaps that's true here.
  The point is that a yellow with enough inherent depth to hold its own
in a tricolor, printed strong enough to hold its own in a tricolor, is
probably not going to print with as many steps (at least that is my own
sense) as a pigment like thalo. So while it's a sort of general rule
that lighter tones print with more steps than darker tones, it isn't
that simple, because it also depends on the pigment and the pigment
concentration, as I keep saying.
Katharine
Received on Sat Dec 3 11:01:05 2005