Eric Neilsen (e.neilsen@worldnet.att.net)
Fri, 30 Jul 1999 09:54:18 -0500
Jeffrey, How long do you wait in between coating and exposure? for wet or dry?
My point being that if you don't wait long enough or get it dry enough, the
paper will have more and maybe quite a bit more humidity.
"Jeffrey D. Mathias" wrote:
> Eric Neilsen wrote:
> > ... it does
> > take some time for paper to adjust to changes in RH. The wet paper would
> > have a hard time getting to an RH of 65%, with out first becoming drier
> > (less RH) than ambient conditions. ...
>
> Several things:
>
> A) I humidify the paper prior to coating. It is almost limp and with no
> "snap" as when it is bent. So there is plenty of moister in the paper.
>
With steam or a sonic mister, in a controlled environment such as a enclosed
box?
>
> B) I have stated before that I do not have any way of measuring the
> humidity in the coating or the paper. I do use a procedure that is very
> consistent and reproducible which I believe to be the important aspect.
> The paper consistently gets to a consistent RH, although I can only
> guess what that RH may be. But most likely I feel it is close to
> ambient. For "dry" the same, I only know it is heat dried to the most
> crispy state I can get it (without charring it.)
>
If it is consistent and repeatable that is good, but how long do you dry it?
did that change from Tucson, to Tampa, to New England? solely by feel?
> C) The point of this test was to compare "wet" and "dry" exposures to
> identify any general differences and that it did. The "wet" was indeed
> moist, and the "dry" was snappy, crinkley dry. Knowing the exact RH
> will in all probability not provide much usefulness.
>
It would provide more information if "wet" was qualified with an measured RH.
Perhaps 75% is too wet and allows the solarized areas, whereas 65% would not.
And as Tony mentioned, it is easy to make a Ziatype, but difficult to be
consistent. This is why knowing the RH of the wet state would be very
valuable. You have produced some very valuable information concerning the
concentration of solutions used in the ammonium based system of platinum
printing (POP), I find it hard to understand how the concentration of water is
being seemingly , dismissed by you. Others may disagree with me, but its the
water content that is enabling the print out, and must be considered an
important component that needs controls. Maybe "needs" is too strong, you can
substitute would be beneficial to control.
> D) I've found that letting the coating sit around before exposing does
> more harm than good.
>
I have not found that, but then again, my darkrooms have been neither hot - I
keep them @75F to 65F, nor full of UV light leaks. Humidity also allows thin
papers, like Beinfang 360, to lay flat. The paper is kept dark and cool during
its time in the humidifying box.
>
> Carl Weese wrote:
> > I think we'll need to see if the 82 degree
> > temperature is having a big effect, as I suspect it might.
>
> I suspect it might as well. Although I have only detected and
> documented temperature susceptibility with POP, not with DOP. But that
> could only mean that I haven't noticed the effect yet or have and not
> pinned it to temperature.
>
> I will be repeating this test when one of three things happens.
> Rosemary finally lets me buy an air conditioner (yea, after we finish
> all the house renovation, including her office); City of Tampa pays me
> the balance they owe me from last August for some prints; the cool
> weather gets here. I've got humidity control, heating, heat exchanger
> ventilation system, but no cooling yet. Who'd think it'd stay so hot so
> long here in New England. And I never noticed (or recognized) problems
> due to temperatures less than 100F until I did POP. I have never
> studied solarization either since I never had a problem with it.
>
> --
> Jeffrey D. Mathias
> http://home.att.net/~jeffrey.d.mathias/
Heat and light will make the reaction move forward. We also could say that
water, as a weak developer in DOP and as the developer in POP, is also not
desirable in excessive amounts during our "dry" steps. And it is also not
desirable to have a damp piece of paper waiting for its turn under the lights.
I too, will conduct some additional test of crispy dry vs. humidified and share
those with you.
EJ Neilsen
-- Eric J. Neilsen 4101 Commerce Street, Suite #9 Dallas, TX 75226 214-827-8301 http://home.att.net/~e.neilsen
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