Occasionally, when I see these discussions, I consider cleaning my trays. More
occasionally, I might sneak some of them into the house and fire them through
the dishwasher. I feel if its survived that, its probably pretty inert.
Beyond that, I might consider the cost effectiveness of Fancy solutions, hard
to dispose of chemicals, vs. buying a new tray. I have yet to see good research
showing that slightly stained trays will have a disastrous effect on
conventional river image workflows, though I could see catalytic effects having
some impact potentially on some obscure alternative processes.
Best
Dr. Laurence Cuffe
On 9 Jan 2021, at 03:40, Mark Sampson (Redacted sender "msampson45" for
DMARC) <dmarc-noreply@xxxxxxxxxxxxx> wrote:
I wouldn’t be caught dead using that stuff.
But then the trays in my darkroom (some 40 years old) aren’t exactly
pristine, either. And no stains on my prints...
Mark S
Sent from my iPhone
On Jan 8, 2021, at 7:38 PM, `Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
Cyanide is very effective for silver iodide. Wet plate and I think also
Dags use silver iodide sensitive coatings. Thiosufate has a difficult time
with it although ammonium thiosulfate is more effective than the sodium
salt. The negatives for making half tone plates also used the wet plate
process. For a long time cyanide was used as a fixer but also in
Monckhoven's intensifier. Monckhoven's has the odd property of being
simultaneously an intensifier and a reducer. It reduces the lower densities
while intensifying the higher densities, thus it very greatly increases
contrast. The purpose was to sharpen the edges of the half tone dots.
Monckhoven's uses a combination of a cyanide bleach with a mecuric chloride
re-developer. Thus is contains two of the most poisonous substances known.
The original method of making halftone plates continued in use until perhaps
the 1950s although other means slowly replaced it. At least into the 1930s
any newspaper office had a lot of poisonous material in its darkrooms (and
maybe its editorial department too). Cyanide as a fixer can be used with an
iodine bleach to remove black spots from negatives and prints, the cyanide
does not leave a stain behind. Now, someone say "I wouldn't be caught dead
using the stuff".
On 1/8/2021 5:54 PM, Howard Efner wrote:
Back in the wet plate days, cyanide was used as a fixer instead of
thiosulfate. It gave a whiter image especially for Ambrotypes.
Howard Efner
73 de KF5RGU
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
WB6KBL
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you
subscribed,) and unsubscribe from there.
============================================================================================================To
unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you
subscribed,) and unsubscribe from there.
