Cyanotype - Midtones Disappearing

Rissy F · Sep 3, 2018

Hi all,
This is my second time trying photogram cyanotypes using foliage and flowers. The first time I was exposing in bright sunlight. I liked the prints and got some cool midtones on some, so I wanted to play with exposing on a more overcast day so I could do longer exposures and achieve more midtones.

Yesterday I tried some test exposures and got a print with some nice midtones. It was a 30 minute exposure and the foliage I was using must have had enough transparency to get some of those midtone values, which I saw after I was done rinsing.

I dried the print on a drying rack in a cellar with very little sunlight getting in (if that matters). When I went back later to look at the dry print, all of those midtones had disappeared.

Any ideas why some of the tones seen after rinsing would disappear after drying?

I tried a second batch of prints after that test. There was less light - there was more cloud cover and it was later in the day, so no direct sun. Once I rinsed those prints, all of the blue washed off and the paper is light gray with very faint images of what I was printing. I was wondering if there just wasn't enough UV to properly expose the paper, or if I rinsed too vigorously, or both. Those prints also faded more after drying. When I was printing that second batch, they looked exposed (visible emulsion was darker greenish-blue, underneath the foliage was still yellow.
Is there a possibility that something is preventing the blue from adhering to the paper?
Or I'm wondering if I either needed a MUCH longer exposure, or if cyanotype just doesn't respond to super long exposures (over 45 minutes)?

Images below of the disappearing midtones.

Here are some other facts about my process:
- Coating my own paper with original cyanotype formula from Photographers Formulary
- I have had the (unmixed) chemicals for 1 year stored in their original dark plastic bottles
- I'm using the same paper as I did the first time I did cyanotypes (last year)
- Using tap water from the hose, but I also did this last year. I do not know the pH of my water.

Thank you for any advice!
-Rissy

Vaughn · Sep 3, 2018

My first impression is that the coated paper was not sufficiemtly dry before the exposure was made. I have seen that color (purple) in my print highlights before with too-wet paper and have seen those values disappear upon developing.

Vaughn · Sep 3, 2018

And it might be due to the moisture in the plant material. For that, try placing a very thin sheet of mylar as a vapor barrier between your coated paper and the plant material.

Also, try open shade on a northside of a wall or building, with the contact-printing frame towards the sky. Lots of UV to expose the cyanotye without over-heating the glass of the contact-printing frame (over-heating brings the moisture out of the plant material). Some like to kick-start the exposure in the sun and transfer to shade before it warms up too much.

Edited to add: Another thought -- the prints that had mid-tone values that disappeared while drying (not previously in the wash). The chemicals probably did not disappear/leave the paper -- I wonder if any image would return by using one of the many toning methods.

Mainecoonmaniac · Sep 4, 2018

First off, your cyanotypes with the midtones are beautiful. The ones without it are also nice. After you develop your prints in plain water, have you tried to intensify the print in a bath of very dilute hydrogen peroxide?

Vaughn · Sep 4, 2018

Hydrogen peroxide will not intensify the image any more than normal drying does...it just hurries up the normal oxidation of the print. If you want to intensify -- a quick soak in a dilute solution of Ammomium or Potassium dichromate will do that for the old formula!

Mainecoonmaniac · Sep 4, 2018

Vaughn said:
Hydrogen peroxide will not intensify the image any more than normal drying does...it just hurries up the normal oxidation of the print. If you want to intensify -- a quick soak in a dilute solution of Ammomium or Potassium dichromate will do that for the old formula!

I didn't know about the old formula. But I treat dichromates carefully. It's a carcinogen.

Vaughn · Sep 4, 2018

I use it for carbon printing all the time. Dichromate is in the new Ware's formula. But yes, care is needed for all chemicals...even water can kill you.

Anon Ymous · Sep 4, 2018

Vaughn said:
Hydrogen peroxide will not intensify the image any more than normal drying does...it just hurries up the normal oxidation of the print. If you want to intensify -- a quick soak in a dilute solution of Ammomium or Potassium dichromate will do that for the old formula!

Potassium and Ammonium Dichromate are both oxidising agents, just like hydrogen peroxide. I certainly see no reason to use them instead of peroxide.

Vaughn · Sep 4, 2018

Because hydrogen peroxide will only darken a cyanotype as much as it will darken on its own over time -- dichromates will take it much much further. Night and day difference. This is from personal experience in both doing and teaching cyanotypes -- you'll have to ask a chemist why.

jim10219 · Sep 4, 2018

I've never heard of washing the print in potassium dichromate afterwards. What I've always done is mixed the potassium dichromate into the cyanotype solution before coating the paper.

For the OP. I've noticed cyanotype chemicals losing some of their range after they get old. I recently had an issue with my cyanotypes losing their highlights. My chemicals are about a year old as well, and they've been stored in a cool, dark place. They still work, but I'm finding I have to adjust the exposure times and paper treatments to get the similar results as I used to, with much less effort. You might also try using some vinegar in your clearing bath. That's supposed to up the contrast, which might help you in your case. Also, since you're using the sun, exposure times are always unpredictable. You might try longer exposures. And like Vaughn suggested, you likely have some moisture problems as well.

Vaughn · Sep 4, 2018

jim10219 said:
I've never heard of washing the print in potassium dichromate afterwards. What I've always done is mixed the potassium dichromate into the cyanotype solution before coating the paper.

The results are instantaneous. I put the (WET) cyanotype (image up) in a tray, pour some dilute dichromate (2 or 3 percent in water) directly onto the print, swirl it around for a couple seconds and dump the tray back into the bottle of dichromate. Sometimes I will squirt a little water in the tray to wash some of the dichromate off the surface of the print, and I put that rinse water in the dichromate bottle, too, if it is low. Then I wash the print until all the yellow is out. The minimum time in the dichromate does not allow too much dichromate to soak into the paper. I try to keep the cyanotype on the bottom of the tray to reduce how much dichromate gets soaked into the paper from the back.

edited to add "WET"

Andrew O'Neill · Sep 4, 2018

Cool! Thanks, Vaughn!

Vaughn · Sep 4, 2018

I forgot to mention that it is a wet cyanotype print I pour the dichromate onto.
I am assuming there is no need for a dichromate bath if using the New Ware cyanotype process, since it already has the dichromate in it.

BJ68 · Sep 7, 2018

Do you make a photogram https://en.wikipedia.org/wiki/Photogram
If yes and you use plants as object, than in my experience it´s normal that "the midtones" are disapperaing. see the cyanotypes of Anna Atkins for example.
Or I am wrong?
For midtones you need a digital negative and not an object which blocks the UV.

Bj68

Dibbd · Sep 11, 2018

That violet colour you are getting in the midtones reminds me of the colour they go initially when you use washing soda to bleach prior to toning. Could you have alkaline water that is continuing to bleach the image slightly as it dries? If so acidifying the clearing bath could help.

J 3 · Sep 25, 2018

If you are interested here is an article on using vinegar as a contrast control for cyanotype. The more acidic the clearing bath, the more midtones you get - http://www.alternativephotography.c...yanotypes-non-toxic-midtone-contrast-control/

J 3 · Sep 25, 2018

P.S. Exposure matters though of course. In order to get midtones the area below the leaf has to be in the exact right exposure range and that is dependent on how much UV gets through the leaf. Even the mildest of overcasts can change the relative balance of visible vs UV light making it hard to meter for cyanotype.

removed account4 · Sep 26, 2018

Andrew O'Neill said:
Cool! Thanks, Vaughn!

+1 !!

Svenedin · Sep 27, 2018

I'm not an expert in cyanotypes but I have made quite a few using the traditional formula. I mix up the solutions from the dry chemicals and use them within a few days. I tried various papers, some more successful than others. I tend to coat the paper quite thickly and then hang the paper to dry in the darkroom overnight. I wonder whether a little tween would help (it helped me get the coating to soak in better). I also wonder whether your midtones are just a bit too underexposed so that they wash off. There is always some detail that is lost in the wash. Do be gentle when you wash.

Cyanotype - Midtones Disappearing

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