Re: what I've learned about cyanotype thru PDN

Seriously??? This is so interesting. I've now added your info to my alt
process tidbit file...

Why does humidity affect it this way, and one metal and not the other? Is
it what Loris says, I wonder, about the ions??? (Loris says > In my
understanding the speed should be faster when the "paper" is more>
moistened - because more iron(III) ions are free to act as a sensitizer.)

Probably another one of those things that we can surmise about til the cows
come home, like crosslinked gum.

Eric, I can make one guarantee; I will NEVER be a master pt/pd printer.
That is 100% sure. I'll leave that to you techie types. But you're right:
I only use the NA2 stuff, so only a modicum of pt in my pd mix.
Chris

> Chris said "So I think you may be talking about humidity being a speed
> benefit (for sure in pt/pd, maybe in cyanotype) vs. uneven moisture, which
> is not."
> Oh master (although not of pt/pd printing), Not always. One needs to make
> a
> distinction between PT and PD when talking speed and relationship to
> humidity. PT is slower at high humidity than at low humidity. PD is
> slower
> at low humidity and faster at higher humidity. Both have relatively flat
> speed changes in the 50% range. This is one reason that printing PT/PD
> printing at 50 to 60% will produce prints that don't change speed due to
> humidity. Another aspect of PT/PD is change in color based upon RH.
> If you make your prints with only trace amounts of PT then you may indeed
> have a hard time seeing either speed or color changes due to humidity.
 Eric Neilsen Photography
Received on Sun Jun 5 20:48:24 2005