From: Joe Smigiel (jsmigiel@KVCC.EDU)
Date: 04/03/02-10:18:07 PM Z
As I recall, the absorption flatlined at almost nothing in the visible around 400nm and there was a very slight increase around 600nm. The visible response was so insignificant that I didn't keep the test around. I found a huge peak in the short UV (UVA ?), a second peak at 370nm (which corresponded closely to other reports I had read (peak at 365nm in the longer less dangerous UV for dichromate) and hardly anything in the visible. By analogy, the short UV peak would be Mt. Everest, the 370 peak Michigan, and the visible, New Orleans.
Joe
<<< kthayer@pacifier.com 4/ 3 4:24p >>>
Sorry, for some reason the quote function on my mail program didn't pick
up your first paragraph, which I meant to comment on:
Joe Smigiel wrote:
>
>>>>>I suspect the actual color of the ink is of little consequence in the effect. If the particular ink/stain is a
window to UV, then as Jeffrey suggests, the sensitizer will be affected
regardless of the color of the ink. When I
tested the absorption spectra of ammonium dichromate a few years ago it
had very little absorption in the visible
wavelengths. >>>>>>>
I thought I'd read somewhere that dichromate has a secondary
sensitivity peak around 420; I take it that was not your observation?
>>>>>As a result, I would not expect any color to affect it. I did test the spectral negatives and found
the results poor compared to conventional negatives and inkjet negatives
produced using Cone piezography quadtone
inks (carbon based?).>>>>>
This is certainly consistent with what I've seen; although I haven't
tested the Cone inks, I got much better results with regular black ink
than with the colorized negatives for printing gum.
kt
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