Cyanotype subjects

[Loris Medici]

You don't have to include dichromate in the New Cyanotype sensitizer; it's an optional addition. Just mix smaller batches that you'll be likely finish within 2 months... Dichromate is for preservation up to a year. (Noted in Mike Ware's article.)

Cyanotype-Rex was a total disaster for me. Pretty messy (incredible staining/bleeding) with a very strange non-linear tonal response and absence for clean whites. Plus, I don't like the fact that one has to mix developer(!) very often (if not, staining is inevitable/even worse) because you end up using a lot potassium ferricyanide which makes the process relatively expensive and environmentally unfriendly. Also, I don't like Ferric Oxalate at all. (Because of poor keeping qualities, very few suppliers, expensive, ...)

Yes dmax is fine indeed but the other properties makes me stay away from it forever.

Regards,
Loris.

I can't use New Cyanotype because it contains dichromate, which I react to even when very dilute, and I do my processing in bathroom.

But a variation of Cyanotype Rex worked very well for me. Not only does it have excellent d-max, the pigment doesn't bleed across the paper, a problem I had with formulas based on ferric ammonium citrate. Note that Rex is not a real printing-out formula. It's more like platinum printing. The image appears in the post-exposure bath, which contains the potassium ferricyanide.

I got a formula from Gustavo Castilla, but I don't think it's exactly what I used. Here's what I did:

Coating solution is 20 percent ferric oxalate, 10 percent oxalic acid. Possibly a drop of Photo-Flo as well, depending on the paper (I used Crane's 90lb Cover). Without Photo-Flo, the image I got was very superficial, coming off in the bath.

Expose 2-2.5 min in direct sunlight (this is faster than regular cyanotype)

Develop/clear in:

1l water
2 tsp potassium ferricyanide
2 tsp citric acid

Then move to a water bath. I used some drugstore peroxide in this bath to immediately reveal the d-max and make it easier to evaluate the print.

 

[Loris Medici]

I got this "occasionally" with some papers, especially in very humid climate. When it works, it works fine indeed. That's why I included in my suggestions. (But with reservations...) It's worth to try and see if it works for them.

And believe me you won't be able to get the overall smooth tones and subtle highlights you can get with New Cyanotype using any other method...

Regards,
Loris.

Interesting. I've been using the traditional 2 part formula and double coating all this time and never had crystallisation issues and can get very dark blues and pure whites.

 

[psvensson]

You don't have to include dichromate in the New Cyanotype sensitizer; it's an optional addition. Just mix smaller batches that you'll be likely finish within 2 months... Dichromate is for preservation up to a year. (Noted in Mike Ware's article.)

That's interesting - might be worth another shot then. I tried New Cyanotype and got terrible results, which I only later understood was due to bad ferric ammonium oxalate from B&S.

I got good gradation and highlight rendition from the developing-out process, but perhaps not quite as good as is possible with New Cyanotype. I think the big step up is going from citrate-based sensitizer to oxalate. With citrate, there's simply too much image washing away in the clearing bath.

 

[Loris Medici]

Psvensson, it depends... With New Cyanotype theres almost no image washing away. With traditional formula you get too much or very little depending on formulation, paper and application. For instance, I currently use 2A+1B (A:20%, B:8%) traditional formula on very smooth side of thin machine-made Japanese paper (Masa) and I get absolutely no (or almost no) blue in wash water (just like New Cyanotype); I apply the emulsion using a high quality syntethic brush, take my time while brushing, passing over the same spot at least 5-6 times (without abrading) and leave the paper in peace for 10 minutes (to let the emulsion soak into the paper). Then I force dry with a hairdryer at hottest setting (to eliminate inconsistency related to humidity). Dmax is not the best but is more than enough for gumovers...