Re: what I've learned about cyanotype thru PDN

From: trevor cunningham ^lt;[email protected]>
Date: 06/05/05-08:30:27 AM Z
Message-id: <>


In Egypt, about the only thing I can get my hands on
is Fabriano, and there is a huge variety. I'm
currently using Gentile. Here's a print I did with
this (i slowly pass the print through a hydroperoxide
bath before the final bath):

the spottiness is likely the paper texture as scanned

--- "Christina Z. Anderson" <>

> 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.

"The optimist believes this is the best of all possible worlds.
 The pessimist fears it's true" - J Robert Oppenheimer

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Received on Sun Jun 5 08:30:38 2005

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