Re: New, safe pigment process

Luis Nadeau (nadeaul@nbnet.nb.ca)
Sat, 22 Apr 1995 03:28:32 +0300

>>>My message -to members concerned about dichromate toxicity- was simply
>>>this: there seems now to be a safer alternative.
>>
>>To this effect, I am anxious to know what the solvent is.
>>Luis Nadeau
>
>I can't say; but you might make some inferences about its hazard from one
>of the photographs in the AP article, which shows Dunstan Perera processing
>a print - and merrily puffing his pipe.

I can't help but being a bit cynical in such situations. I had a visitor
from Paris last year, who, like most Europeans, is a smoker. I was selenium
toning a print in my lab and explaining to her that the stuff was pretty
dangerous, etc., when she suddenly appeared "shocked" because I was
exposing her to a dangerous chemical... I paraphrase and translate myself:
"Mademoiselle, I would like to remind you that you should always keep
things in perspective. When you smoke a cigarette, you are exposing
yourself and everybody around you to approximately eight hundred and fifty
(850) identified carcinogens... You are presently exposed, for the first
time and probably last time in your life, to a solution of water (95%) and
selenium toner, 1 cm deep in a small tray, and you are standing 2 metres
away, so please, don't panic..."

There was much said this week about the alleged terrorist use in Japan, of
*phosgene*, a deadly gas used in World War 1. Nobody has to go to Japan or
anywhere else to experience the effect of phosgene. Trichloroethylene
(TCE), used by many as film cleaner, combined with cigarette smoke or
ultraviolet radiation, forms phosgene, right in the privacy of your own
workroom!

I used to use TCE (without smoking) in a "wet gate" for color separation
work. TCE and another solvent provide a diffraction index between that of
most gelatin/film supports, therefore removing "magically" all scratches.

There is more on this in the safety section of my carbon books.

>(Perhaps this is a bitumen process, after all (8-))

with the tar, I suppose;-)

Luis Nadeau

>
>Mike