A question about cyanotype process

[Loris Medici]

Definitely provide us a 31 (or 21) step stouffer tablet print, it tells many things to us. Prints with digital negatives can't tell us - with certainty - if there's something wrong with your chemistry and/or paper and/or workflow...

Regards,
Loris.

 

[Mainecoonmaniac]

Thanks for the tip Loris! I have a 21 step tablet. I used it on earlier test. Cyanotype sure contrasty. I use Chart throb to figure out the photoshop curve of the digital neg.

 

[Loris Medici]

Can you please share the 21 step tablet test that you've made before with us? It would be nice to asses if you've correctly nailed down several analogue aspects of the process before digging into the digital negative making.. (Which is out of topic here.)

Were you be able to get at least log 1.4 density range with the step tablet? (Something between 9-10 steps with the 21 step tablet...)

 

[Mainecoonmaniac]

Thanks for your help Loris!

Can you please share the 21 step tablet test that you've made before with us? It would be nice to asses if you've correctly nailed down several analogue aspects of the process before digging into the digital negative making.. (Which is out of topic here.)

Were you be able to get at least log 1.4 density range with the step tablet? (Something between 9-10 steps with the 21 step tablet...)

Hi Loris,
Here it is.

The cyanotype test has 3 parts.
1. The top gray scale os Chartthrob's with curve applied in attempt to correct for the cyanotype curve.
2. The middle scale is the Stouffer step tablet with ink jet material overlay.
3. The bottom gray scale is just the Stouffer gray scale.

So what does this tell you?

Thanks,
Don

 

[Loris Medici]

Hi Don,

First of all, the paper doesn't seem to be perfectly compatible with cyanotype. I can see chemical fog in the test, you don't have clean whites. Also the darks lack substance, but that may be due the repro. I also see some white spots here and there indicating absorption problems. (Some fibers not accepting the sensitizer and/or crystallization of emulsion on the surface - crystals will wash off and leave spots behind...) Apart the fog and low dmax, the tonal progression looks OK. (I see a range around log 1.6 which is fine...)

What paper is that? Have you tried to de-alkalize with sulfamic acid? (Look at the archives for sulfamic acid treatment...) This paper obviously not the best match for the process - as it is. Have you tried other papers?

Do you use any kind of surfactant?

A note: I understand this is the test print for the curve, placing the step tablet on the edges isn't a good idea actually; edges usually coat different. I always test at the final image size and place the step tablet in the middle. Coating small amounts of sensitizer vs large amounts sometimes makes a lot of difference...

Note 2: (It's off topic here but will mention anyway) I don't think your ink / color selection is correct, is that yellow pigment? (Looks like the results I've got with yellow; yellow is not a good color for making negatives...) The tonal progression is bad in the middletones and highlights. This added to the chemical fog you get with this paper gives you flat results with poor tonal progression.

Regards,
Loris.

 

[Mainecoonmaniac]

Hi Loris,
Thanks for your input. Yes I think it is chemical fog. I used a chemical tray that had residual chemicals that I'm sure contaminated the emulsion. The paper I'm using is Windsor Newton Cotman. I did a test for digital negative and one the colors that seemed to block UV is a reddish orange. So I'm wondering if the curve is close, but the chemical fog is ruining the tonal progression? I'm very impressed by your knowledge of cyanotypes.

Best,
Don

 

[Loris Medici]

Hi Don. Thanks, yes, I'm good at cyanoypes (and many other alt processes). Once you get around problems with cyanotypes, you gain a lot of experience useful in the domain of other iron / iron-silver processes. (I mean, don't give up but persevere; you'll learn a lot and your technique / knowledge will improve a lot...)

First of all try to make a nice step tablet print with clean whites, good tonal progression and nice / clean (spotless) blacks. The digital things will have to be dealt later. (For starters, greenish colors usually are better in terms of UV blocking and tonal progression...) Try some other papers, this one doesn't seem good for the process. (Fabriano Artistico Extra White treated with sulfamic acid works like a miracle and is a very very good paper which works wonderfully for pt/pd and gum - all after sulfamic acid treatment. You may try sulfamic acid treatment with Cotman too.) There are some paper that work good w/o any pre-treatment. For instance, try Masa if you are not going to be put off by thin papers. It's cheap, gives very clean whites, dark blacks, very good contrast and definition.

Regards,
Loris.

P.S. In case of Fabriano Artistico Extra White and gum only, you don't need de-alkalize the paper. But if you want to make gumovers, (gum over cyanotyope, gum over pt/pd) then you have to get rid of calcium carbonate buffer in the paper.

 

[Mainecoonmaniac]

Hi Loris,

Thanks for the tips! I'm trying out different papers for Ziatypes. I just bought a batch of Revere paper from Bostick Sullivan. But for now, I'm going to concentrate on the cyanotype process. Do you think a soaking of weak citric acid will help with the Cotman paper? I will try a a green color on my inkjet printer for my negatives. I think you've save me some time an aggravation.

Best,
Don

 

[Loris Medici]

Probably Revere will work well with Cyanotypes too. See (there was a url link here which no longer exists) for a nice method of de-alkalizing calcium buffered papers.

Good luck,
Loris.

 

[Mainecoonmaniac]

Hi Loris.
You've been a great help. I looked you up and your alt process prints are impressive!

Best,
Don