Re: what I've learned about cyanotype thru PDN

Loris,
You are absolutely right that lavender color comes from alkalinity,
(especially if you are using Ware's on the wrong paper you'll get horrible
lavender highlights and the rest will be a dull grey blue). This lavender
was directly the result of moisture left in the paper, because it had a
wonderful bloom mark around it, like you get when you watercolor. I could
replicate it I would think if I wanted to drip drops of water on the paper 5
minutes before exposure. Try it and you'll see what I mean (and probably
damage your neg).

I have seen, therefore, lavender associated with both causes. To duplicate
the alkaline cause, all you have to do is coat the cyanotype with Future
floor polish and it turns wonderful lavender immediately. But that, too,
will convert back over time.

How I can tell that the speed is slower in this moistened area is that when
the tonal palette finally dried and after 24 hours went to the deeper thalo
blue, that area is also blue but paler in tone throughout the steps that the
spot covers. It was on the edge of the print where the excess cyanotype
solution must have leached back into the center more, without my seeing it
by eyeball.

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.

The humidity thing with cyanotype: here humidity ranged from 58%-77% over
the last several days. As I waited the exact time between coating and
exposure with each of my tests, I can compare those and see if that range is
an effect (it was not) but the real test will be when I return to Montana in
August and have 20% humidity there and do the whole testing process again.
Until then, I cannot tell whether humidity increases speed or not (as it
does certainly in pt/pd) as I only have a limited humidity range in the high
values here. It may be that cyanotype responds the same as pt/pd with this
variable.

I remember testing the old adage about gum being insensitive when wet. It
isn't. But I guess it boils down to how wet is wet, or at what point does
too much moisture create a loss of speed, but some moisture increases.

It could be (my guess from gum) that two variables that have great effect on
alt processes are humidity and acidity/alkalinity. A "fast gum" may be an
acid gum, etc. etc. blah blah blah.

One more thing I learned: I forgot I had put hydrogen peroxide in my
development bath, and developed a test print immediately in that (in other
words, first development bath had hy per in it, it wasn't added after the 15
minute development) and I lost a stop and a third of speed. So not only, in
my book, is hy per unnecessary, but unless you need a loss of speed it
should never be in the water. What is so odd about hy per is that my finger
was wet with the hy per water bath, and I just touched another wet cyanotype
print, and that miniscule amount of hy per on my finger immediately darkened
the print. And that is a dollop of 20v hy per in a huge bathtub of water,
so I'm not talking a lot.

Trevor, I'm getting a brilliant blue only waiting 20 minutes after coating
to expose. Have you tried Arches Platine?
Chris

----- Original Message -----
From: "Loris Medici" > I always thought that the lavender color is connected
to the alkalinity of
> the paper. The more alkaline the paper, the more lavender color you get.

> 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.
> The
> constast also should be lower - because the emulsion is more sensitive to
> light. And if the paper is more dry then there would be less free
> iron(III)
> ions, therefore less speed and more contrast.
Received on Sun Jun 5 08:04:48 2005