Re: Carbon Printing UV/Cool White

Judy Seigel (jseigel@panix.com)
Tue, 9 Jan 1996 15:21:56 -0500 (EST)

On Wed, 10 Jan 1996, Mike Ware wrote:
> (Technically: the spectral power per unit
> bandwidth must be integrated over the wavelength range).

Ahem. Would you repeat that in plain French?

> should be remembered that the sensitivity of iron-based coatings (e.g.
> cyanotypes or Pt/Pd) is different intrinsically from that for
> photohardening of dichromated colloids (e.g. gumbi and Carbon). So it is

And it should be added that there seems to be a great difference between
response with gum emulsions and with gelatine emulsions tho both are
dichromated, as my findings were quite different from Sandy's. Think I
didn't post this to list yet, but preliminary tests with gum by cool white
fluorescents show they take about 3 times the light that black
lights do and even so I cannot get comparable *number* of steps. Contrast
by the cool whites looks dandy, much prettier in fact, but alas only 3, at
most 4 steps -- so far.

> Two differently pigmented carbon tissues, for instance, will not be of the
> same 'speed' even if the dichromate concentration is the same.

And how. For instance the test in cyan blue comes out strikingly different
from burnt sienna, etc. Seemingly different profile for most colors....

> At this point, the scientist bows gracefully, admits that the real world is
> far too complicated for him to quantify, and retires to make some prints
> instead.

But upon making the print, i.e., "art," the critical ego returns to taunt
her with her insufficiencies. "Science" happily lacks this anxiety, the
result being, by definition, its own justification.

Judy