From: Judy Seigel (email@example.com)
Date: 04/09/02-08:02:43 PM Z
On Tue, 9 Apr 2002, Eric Neilsen wrote:
> Bob, Where is your evidence for the heat drying with platinum and reduced
> steps? This sounds more like a change in RH and not a heat issue.
I haven't made the test in platinum, but I've made it in VDB and
cyanotype, and my students made it repeatedly. (They were required to do
two "variables tests" per semester, and this was one of the easiest !).
Print two 21-steps, let one air dry, heat dry the other. Expose & develop
the same. The heat-dried print loses density and contrast. The degree of
change is related to the other variables, including how hot the drying,
how long, and how soon -- If the heat is mild and just a finishing touch
the change is probably minimal.
However, since a plain electric fan in the vicinity dries the emulsion
just as quickly, there seems no special point -- for those emulsions. In
my limited experience with platinum/palladium I found I had to heat dry
after x amount of time, or the emulsion sank in & made a dull flat print
-- in the combo I was using.
In other words, for most media I've used, drying with heat is a REAL
VARIABLE -- definitely changes results, IME for the worse, except with
I don't mention gum here because I wouldn't dry with heat in gum at all --
I suppose a mild finishing touch is again no problem, but real heat simply
cooks the emulsion & it will not clear. I also discovered the hard way
that even if the print clears when it's dried with heat, it loses speed by
about 80%. (I was doing a gum workshop with lights I'd never used. Asked
the teacher exposure time. She said 15 minutes. The prints cooked. The
time turned out to be 3 minutes. Later the light bulb lit -- she had
always dried her gums with heat !)
Heat drying gum, BTW, is often *the* problem when platinum printers decide
to try it & run into problems. They'll dry the gum emulsion the way they
dry platinum -- with heat -- unless warned in advance.
> in RH can be achieved without heat as well. I have not seen that. I would
> suggest that any drying or air movement would take some particles of the
> coating solution with it. Platinum has been shown to be associated with
> asthmatic condition. Any platinum spill should be cleaned up right away.
> As for Pot Ox, I would be more careful of using it warm or heated. If you
> use multiple trays, having one with Pot Ox, it should be covered at all
> times when practical.
> EJ Neilsen
> ----- Original Message -----
> From: "Robert W. Schramm" <firstname.lastname@example.org>
> To: <email@example.com>
> Sent: Tuesday, April 09, 2002 4:03 PM
> Subject: Platinum respirator
> There is no need for a respirator for platinum printing unless you insist on
> heat drying your coated paper. This is a bad idea since little particles can
> flake off and drift around the room. Besides, there is evidence that heat
> drying will result in the loss of one or more steps (on a 21 step wedge) of
> I would suggest you wear gloves, however, as the sensitizer can be absorbed
> through your skin. Also potassium oxalate developer, if you use it, is toxic
> and can also be absorbed through your skin. If you use HCl to clear and you
> are working with concentrated acid, don't pour water into acid but I suspect
> you learned that in chemistry class. PS latex gloves won't work. Use Nitrel
> (sp?) gloves (they are blue).
> Bob Schramm
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