Cyanotype sensitiser changes colour when drying

Just kicking off on my first attempt at cyanotypes using Fotospeed pre-prepared sensitiser, which i believe is the same formulation as Mike Ware's new process.

I've coated Ruscombe's Herschel paper (the replacement for Buxton) using a coating rod and mixing in a drop of 20% Tween. I placed a 15W tungsten bulb about a metre away from the coating table and below it's level, so that the coating area receives only dimly reflected tungsten light from the adjacent wall.

The RH at the time of coating was 65 - 70% (if my cheapo weather station is anything to go by).

My problem is - during drying in the dark, the coated area goes a fairly strong moss green and doesn't remain lemon yellow as when first coated.

I understand this is generally caused by paper impurities but i thought the Ruscombe stuff was about as pure and aligned to alternative processes as you could get.

What else could be doing this? Any help would be much appreciated.

Stephen

hmm.

The first question is - you say it's a problem, but how do the prints turn out? It may be a quirk of the Ware process (if indeed that is what the Fotospeed kit is)
I've only ever seen my coated papers turn very green after they've been stored for a few weeks, but then I only make a "traditional" cyanotype recipe from raw chemicals so can't speak for the Fotospeed kit.
Does the Fotospeed kit require dilution or mixing at all? London water isn't always the purest (not in the sense of non-potable, but may contain high levels of e.g. iron)
The first thing I'd do in your situation is try some different paper.
Then I might try acidifying the Ruscombe with a 5% bath of citric acid, giving it a brief rinse, then drying it before coating. However, it really shouldn't need all that palaver.
Alternatively, give Fotospeed a ring. They're still a close-knit lot and I've found them very helpful and knowledgeable in the past

Make a print and see how it looks before doing anything else.

My traditional formula cyanotype did this last time i used it on some paper. I got some of the best cyanotypes i've done despite this.

Don't worry about the coating colour, judge the final prints.

Thanks all, and you're right of course. It's just that everything but everything written about this process says the sensitiser should remain lemon yellow on the paper. But i printed and they look alright. My negatives are way too narrow in their density range but that's another issue. The prints themselves are a lovely blue despite taking forever in my homemade lightbox (8 x 600mm UVB tubes, 6" from the paper). Thought it might be quicker but i'm looking at 30mins for a decent saturation.

Also, in answer to your question pdeeh - the fotospeed stuff doesn't need diluting, you just use as is. At twenty quid a bottle i'm inclined to make my own next time and see if i can add something to strengthen the contrast.

So, appreciate your help and thank you again.

cliveh said:

Why not use direct sunlight?

Click to expand...

In my experience, the sun's intensity changes with time of year and weather, ranging from quick exposures in the summer to "as if it were possible" exposures in the winter (at least in Canada, here)... so a UV box at least creates the illusion of replicability.

Old thread, I know

I haven't played with cyanotypes in a few years, and while looking for chemistry I found a liquid PhotographersFormulary kit on sale... so what the heck
After coating the paper (single coat with a brush) and letting it dry, it seemed a very nice lemon-green. Stored them in a dark envelope and let them sit for a few days for maturing.

As I began preparing for printing I noticed a few of the sheeets had "streaks" of a dark green (more like forest green), I assumed it was my poor brush handling as there seemed to be brush strokes (going up and down or in zig zag) It looked ugly but usable, so I used one of those for exposure testing
The dark streaks exposed faster than the rest and produced a beautiful shade of blue, while the lighter green produced a muted almost bleached look

So my hypothesis is that those are sections where the chemicals deposit more heavily than in the rest of the sheet
SO I took all the sheets and gave them a 2nd coat and they are dry now, will test them later.

Paper Canson XL
Photographers formulary cyanotype liquid kit (traditional)

Stephen Samuels said:

Thanks all, and you're right of course. It's just that everything but everything written about this process says the sensitiser should remain lemon yellow on the paper. But i printed and they look alright. My negatives are way too narrow in their density range but that's another issue. The prints themselves are a lovely blue despite taking forever in my homemade lightbox (8 x 600mm UVB tubes, 6" from the paper). Thought it might be quicker but i'm looking at 30mins for a decent saturation.

Also, in answer to your question pdeeh - the fotospeed stuff doesn't need diluting, you just use as is. At twenty quid a bottle i'm inclined to make my own next time and see if i can add something to strengthen the contrast.

So, appreciate your help and thank you again.

Click to expand...

See the example here; the streaks of deeper green seem to have no effect on the final product after the 2nd coating

Cyano-Angel-flickr

titrisol said:

Stored them in a dark envelope and let them sit for a few days for maturing.

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Why? Cyanotype yields excellent results if you use the freshly coated paper. Having it sit around in its coated state increases the odds of fogging, which will inevitably happen on any kind of paper.
With the right kind of paper (and classic cyanotype is not particularly fussy in this respect), perfectly even prints using only a single pass of coating are quite easy to make. Any necessity of double coating the paper to prevent unevenness or ensure good dmax suggests an unsuitable paper is used or the chemistry is somehow compromised.

Letting them sit for a day or two was in my notes from the 1990s.
Maybe it is not necessary but it was the procedure I followed initially (and documented in the message above)
This is classic cyano, Photographer's Formulary Kit (it was on sale), and since this is a hobby it'll at least dry overnight (coating at night) and sometimes it'll be 2-8 days before I have a chance to print

I think the 2-coat issue is more due to my shady brush-strokes than the paper itself, and the 2nd coat was to obtain a more uniform cover. I'm coating the 2nd transversally to the 1st
However, the 2nd coat made the blue deeper and I like it

love when old threads pop up that i missed first and 2nd time around
i used to coat with a hake brush ( i've never used the new cyanotype formulas just the ones made like hershel and people that varied the amounts of the 2 chemicals )
i realized that a heavy coat with a foam brush works great. if the paper has carbonate in it to make it "acid free" soak it in vinegar, it will bubble, that is OK. if you get hungry from
the salad dressing smell, go have a bite to eat, while you are snacking, let the paper dry then use the foam brush. let the sensitizer sit there wet on the paper to even out, no puddles just wet paper. use a hair dryer on COOL to dry it, then coat it another time maybe even a 3rd time ( these days i coat 3 times ). if you use the olde fashioned formumla it will be yellowy greeny. not sure what color it is supposed to be but it works.
the longer you let it sit around coated ready to go, the paper will contact tinder or grinder or whatever online agency it calls, hook up with the humidity in the air and it will change color.
i've used paper that was 6months or a year old, humidity struck that i thought was gonna be bad but it was kindasorta-OK, not perfect but it worked. you might also consider your first bath having a little vinegar in there in case there is still carbonate to bubble out .. rinse in water then some water with hydrogen peroxide in there so you don't have to wait a week or two or 4 for it to turn blue unless you like to watch the change and all that fun stuff, you know, like your photograph doing performance art.
then rinse in water until it runs clear .. good times !
always wanted to do REX and dr ware's formulas but having too much fun doing the 19th century to bother going back to the future. maybe someday.

happy happy

Yeah, lime color is good. And a hairdryer certainly speeds things up. I quickly gave up on drying the paper on racks etc (no patience). I did keep some paper around for a few weeks and it still worked, but fresh was better. Foam brushes, hair brushes - it all worked quite well. Acidifying the first wash helps clear the highlights faster and modifies the hue of the print; acetic acid shifts it towards cyan, citric acid to royal blue and a very (very!) mild soda bath after clearing the print imparts a magenta hue to the print - but may/will also bleach it.
Classic cyanotype is the most forgiving in terms of papers and requires low contrast negatives, new cyanotype is much fussier in the papers it works with, but prints a few stops faster and gives a very long and seemingly linear tonal scale, requiring negatives with a contrast range of something like 2.2-2.4 which is in the range of salt print negatives.
It's a very nice process as long as you like blue. I had some luck toning them towards maroon, purple and reddish tints with various concoctions of tea, coffee and acorns.

Sounds to me like the paper is the issue. Try acidifying the paper in a vinegar, citric acid, or sulfamic acid (which I prefer) bath. Rinse, dry, and coat.

I went through an intense period of making cyanotypes a year ago I must have made a couple hundred. Did all kinds of experiments. Like Andrew, soaking the paper in Sulfamic Acid then washing it before coating made the biggest difference. Acid all around is the key if you want to make something with tonality. You can get a full scale print with a cyanotype. It isn't that simple, but it is doable.