Question on Shelf Life of prepped Cyanotype Paper stored in Dark Bag

So I’m just getting into Cyanotypes and will be using the PF 2 part liquid on Strathmore 400 Watercolor Papers. My goal is to use Mother Nature as my printer.

However lately she has been pretty scarce on weekends, though emerging by surprise for an hour or two. Given my family life as a Dad, I ideally would have the paper coated the evening before and ready to go when the Sun makes its appearance.

But what if a promised sunny day fails to pan out? I read anecdotal bits that the prepped paper is best used within a day or so, but I’m curious among those here who do cyanotype printing as to what you may have found to be a practical shelf life for coated and dried cyanotype paper stored in darkness or near darkness. Any precautions?

Since at least one seller sells preprepared cyanotype paper in a dark bag to use when desired I had to wonder how practical this same premise is on materials that one coats themselves.

hi meyer trioplan
i was /am in in the same boat
the sunprint paper people in berkley make their emulsion
based on the classic formula, they tweek it a little i was told
so they can precoat but i don't know the shelf life.
( i know there are other people that sell precoated paper i've never talked/bought from them)
i have a bunch of paper i am using that i coated a few weeks ago
( maybe even a month? ) it seems to be OK ... when it gets humid/summery they turn kind of darkish
i wouldn't worry about a couple of days or a week
even if it was humid ( unless you live in the tropics )...
i'm not using fancy paper like you ( that might be more absorbant to atmospheric humidity )
but cheap art store pad paper, virgin butcher paper and "security" envelopes .. so that might be a factor too..
you could always coat a handful of scraps put them someplace and once a week or 2 weeks or 3 weeks
take one out and make a print with it, and do your own controlled experiment
have fun !
john

I did my very first cyanotype coating last year in summer and used a sheet or two this summer. There was no problem. I still have some left and I don't see why I couldn't use it next year (two years old, then).

I feel that people here worry too much about the stability of stuff. I mixed 5L of cine developer, used it once and then continued after a six month hiatus. My Spur HRX had been open for more than two years. My CD3 powder was of good quality and is fine after two years (someone with cd3, probably very impure, from China reported here that it goes off).

In a dark bag your sheets will be fine.

I'm betting there are a lot of factors at play, such as the kind of paper, prep of the paper, the actual chemistry used, humidity, etc. I've never had a problem coating paper a day before, but I've had three day old paper fog up on me pretty badly, to the point of being unusable. I don't remember what paper exactly it was, and ever since then I have always coated the paper either the same day, or the night before to avoid such issues. I can tell you that I'm using Photographers Formulary original Cyanotype as my chemistry. And that was before I acidified my papers.

Awesome to see the sampling of some of your real world experiences. Thanks All!

John and Jim - both of you have some very good viewpoints concerning the variables at play, which I was trying to consider, and its interesting to hear the experiences. I definitely am up for the idea of doing a coating a pair of small examples using all of three different samples of stock paper of variable qualities - printing one set within a day (using the same control negative for the same time) and then doing a follow up set on the coated stored paper a week or two later to see the differences. I have some Cyanotype Store coated paper coming in addition to act as some "at the ready" paper, and would be curious what might tweaks might be done to improve the shelf life of these commercial papers.

lantau - Very much agreed that a lot of people in the film hobby tend to be a bit too reactive regarding stability of products. Some of the very negatives I'll be looking to print cyanotypes from will be recent exposures taken on film that expired in the 1940's and 1950's, and others will be on fresh stocks. Looking forward to the experience even if Mother Nature isn't too willing to let me indulge in it!

Fog will set in at some point - if it's in a matter of seconds or months depends, as has been pointed out, on many variables, but the composition of the paper itself is in my experience the #1 factor that determines how long you can store your paper.

To be honest, I gave up coating and then storing paper as soon as I realized that coating and then blasting with a hairdryer allows me to coat-on-demand. It takes just a few minutes to coat and dry a piece of paper. When doing alt prints, I routinely coat the next sheet as the previous one is exposing. I haven't had coated paper sitting around waiting to be used for more than a few minutes in the past 2 years.

Like koraks said. Just coat and dry with hair dryer...It's so quick. You could also buy a UV light and do your exposures inside. I live on the west coast of Canada. This time of year it rains 24/7.

The hair dryer works, but my papers tend to dry within an hour or two, so I don't usually got that route. Also, the good thing about cyanotype is you don't need to do a test sheet to see if it's fogging. When the paper starts to turn noticeably green, it's fogged. It might take a bit of experience to know just how green is too fogged to use, but once you get that part figured out, it's pretty easy to just glance at a sheet and instantly know if it's usable or not.

I also recommend using a UV lamp rather than the sun if you're wanting to get even semi-serious with it. I bought a UV face tanner for under $100 (used) and use that for all of my alt. process prints. It gives me reliable and repeatable results. Plus I can do it at night or on cloudy/rainy days. And I never have to check a print mid exposure or do a test print once I've figured out the times for the particular process/setup that I'm using. And maybe best of all, I can expose a cyanotype in about 2.5 minutes, which greatly reduces the time I need to make a print.