[Alt-photo] Ageing of New Cyanotype
keith at jkschreiber.com
Tue Mar 27 20:54:37 UTC 2018
It's not clear from the way you phrased your question(s) whether you are talking about the solution or the prints. I think you mean the solution, but it looks like Siegfried read it to be the prints. Please clarify.
I'm assuming you store your solution in a dark brown bottle, and that there is no exposure to UV light.
I've made 3 batches of Ware's New Cyanotype from scratch (not from a kit) since last September, and all were what I would call a medium yellowish-green. Obviously such descriptions are subjective, but they were neither light nor dark to my eye. So maybe something is different with your kit or the way you prepared it. I do think the change of color is a good indication that it's time to make a fresh batch. I also suggest buying the raw materials (ammonium ferric oxalate and potassium ferricyanide) in bulk rather than a kit since it is so simple and inexpensive, and you'll always have more on hand when you need it. (Note: there is also a minuscule amount of ammonium dichromate in the Ware formula as a preservative that might have been omitted in the PF kit.)
Linearization for cyanotype is a moving target in my experience/opinion, since it is so sensitive to small and seemingly mundane changes in processing such as wash time. Do you use an acid "development" step? Time matters there too, along with which acid you use and at what concentration.
Over exposure is essential with cyanotype, both "classic" and "new" methods. C James is right! It is hard to overexpose cyanotype. On a 21-step Stouffer, a good exposure on most papers would appear 6-8 steps (that's steps, not stops) overexposed before development. That means 5-7 steps of reversal! Some of my tests have suggested that overexposure might be beneficial to tonal smoothness as well - something I plan to look into further in the not too distant future. This would require building a negative "curve" in which the Dmin is a full stop or more higher than the film base density.
What paper are you using? I've found Arches Platine to be nearly foolproof.
"Ever tried. Ever failed. No matter. Try Again. Fail again. Fail better."
~ Samuel Beckett
> On Mar 27, 2018, at 12:37 PM, John Isner via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
> A few months ago (much less than a year!), I made my first batch of New
> Cyanotype using the kit from Photographer's Formulary. I created a curve
> following Ron Reeder's method on the Freestyle Photo web site. My prints
> were very good -- until recently.
> As the New Cyanotype aged, it went from a light green-yellow to a dark
> blue-green. By the time I was getting close to the bottom of the bottle,
> my curve was no longer linearizing properly. There was an almost complete
> loss of tonal range in the shadows. I had to discard most of my prints.
> I should mention that I was routinely overexposing my prints. I won't go
> into the reason why, but I didn't think it was a factor because of what
> Christopher James says in his book: "it's hard to overexpose cyanotype."
> Here are my questions: (1) Even though New Cyanotype is supposed to have a
> shelf life of one year, is it advisable to make a new curve periodically? (2)
> Does overexposure become a problem as New Cyanotype ages?
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