How to improve density in Cyanotypes?

[ChristopherCoy]

I like the Cyanotype process, but my biggest complaint at this point is the density of the image. It's kind of there, but not really - not quite sure how to explain my thoughts. It's kind of like looking at a newspaper image up close to me.

Would coating, drying, and re-coating improve the "resolution" if you will?

 

[glbeas]

The image has plenty if density in the shadow area, are you talking about midtone contrast or sharpness? Double coating will give it more punch, you may have to tailor your digital negative curves to accommodate that. Ive found too if the negative doesn't have enough uv absorption the mid to white tones cant be calibrated well as theres not enough numerical separation between each step in the scale. I punched up the ink density on mine and got way better tones but then started having banding problems from the substrate not holding the ink as well. Got some Pictorico Ultra Premium on the way, that supposed to be tailored for Ultrachrome inks and hold more density. We’ll see how that works
.

 

[osella]

I don’t believe double coating will improve the resolution or sharpness of the image, that is pretty dependent on the paper you use. Double coating will give you better density and a deeper blue. The sample you provided actually looks pretty good to me.

Alt process prints definitely have a different look than silver gelatin, mostly because the image is in the paper rather than in the gelatin layer above. They are more like ink on paper which is why they look vaguely like a news paper image. You may need a smoother paper if you want more resolution.

When double coating you don’t have to let the paper dry completely, just enough so it gives time for the first coat to soak into the paper. The double coat may give the impression of more resolution as you will have a slightly thicker emulsion. I haven’t used it myself but a surfactant like tween20 is supposed to help the paper absorb the coating better so you loose less density during the wash.

 

[ChristopherCoy]

You may need a smoother paper if you want more resolution.

.

The first pack of paper I used was Bergger COT-320. The print above was done on cheaper Canson paper. I used the smooth side on both brands of paper, but I feel the same about both. I think your description of ink on paper is spot on, and that's exactly what I don't care for much. At least not in portraits.

After writing in my journal this morning, I also realized that I don't like the absolute necessity of digital intervention. I can't afford the cost, or footprint of an 8x10 camera, so I've got to print my negatives. I think the requirement of a computer and printer ranks right up there with the fact that I just dont like the 'newspaper' resolution.

 

[ChristopherCoy]

The image has plenty if density in the shadow area, are you talking about midtone contrast or sharpness?

I know you've done VDB's, did you find that the sharpness and resolution was better in a VDB than it was in your CT's?

 

[Andrew O'Neill]

What's the RH of the space you're working in? When the RH is low for me, I end up with prints that look like your example, regardless if it's a cyanotype, Kallitype, or VanDyke.

 

[ChristopherCoy]

What's the RH of the space you're working in? When the RH is low for me, I end up with prints they look like yours, regardless it a cyanotype, Kallitype, or VanDyke.

Well, we live on a boat so it's usually pretty high. We do have a dehumidifier on board that keeps most of the boat around 40% RH (at least that's what it's set at). Without the dehumidifier we can easily reach 60-80% RH within a few hours.

 

[bernard_L]

complaint at this point is the density of the image

New Cyanotype (Mike Ware) claims higher Dmax. Since that is the only one I have tried, I cannot comment on the difference wrt "normal" cyanotyype. But definitely requires different negatives because lower contrast: New Cyanotype has a long scale, requiring a density range of 1.6 or thereabouts, as if printing on #0 regular paper. Such a density range might (or not) represent a challenge for injet digital negatives; not for, e.g. X-ray film negatives.

 

[Vaughn]

A quick bath of a weak dichromate solution, then a wash will increase the dmax and richen the blue.

 

[Andrew O'Neill]

Well, we live on a boat so it's usually pretty high. We do have a dehumidifier on board that keeps most of the boat around 40% RH (at least that's what it's set at). Without the dehumidifier we can easily reach 60-80% RH within a few hours.

RH of 40 is pushing it, at least for me and my working space. That's ideal when I'm making carbon transfer prints. My space has to be 60 or preferably higher for cyanotypes, etc. Try soaking the paper in water, drying, and then coating it, to see if that helps.. or humidify it over a boiling kettle, before coating.

 

[ChristopherCoy]

RH of 40 is pushing it, at least for me and my working space. That's ideal when I'm making carbon transfer prints. My space has to be 60 or preferably higher for cyanotypes, etc. Try soaking the paper in water, drying, and then coating it, to see if that helps.. or humidify it over a boiling kettle, before coating.

I'll just stick it in the bilge. LOL

 

[koraks]

A quick bath of a weak dichromate solution, then a wash will increase the dmax and richen the blue.

That's neat, I never realized that. It's similar to the weak peroxide wash I assume?

 

[nmp]

That's neat, I never realized that. It's similar to the weak peroxide wash I assume?

It is same as hydrogen peroxide - both will oxidize the Prussian white to Prussian blue instantly unless you can wait for longer period of time for air to do the job. I suppose unless you have dichromate lying around, I wouldn't go and buy it for this purpose being that it is not a nice chemical to handle.

In my experiments, if anything the final outcome was a tad better (denser blue) in case of natural drying vs the peroxide treatment (which I am sure depends on the length and concentration and I didn't optimize either of them.) I have also found that the natural oxidation can be speeded up at higher temperature. I dry all my test prints in a forced convection oven at about 50 oC and the equilibrium color gets achieved in a couple of hours.

 

[Vaughn]

That's neat, I never realized that. It's similar to the weak peroxide wash I assume?

Totally different than peroxide from my experience. Hydrogen peroxide just hurries the natural oxidation that will happen anyway. The dichromate is very different.

 

[ChristopherCoy]

Totally different than peroxide from my experience. Hydrogen peroxide just hurries the natural oxidation that will happen anyway. The dichromate is very different.

Like Potassium Dichromate?

 

[Vaughn]

Or Ammonium dichromate -- a 1% to 3% solution. Just enough to cover the print in a tray. Happens pretty much instantaous.

 

[ChristopherCoy]

Or Ammonium dichromate -- a 1% to 3% solution. Just enough to cover the print in a tray. Happens pretty much instantaous.

Which one is less dangerous?

 

[Vaughn]

The same.

 

[koraks]

Many thanks for sharing your thoughts gentlemen. I may give it a go. My experience with pyroxide is also that the intensification is quick, but not as complete as doing it the "natural" way.

 

[nmp]

Here's the relavant portion in Mike Ware's Cyanomicon:

>>>>>

light + Prussian blue + ferrous ions ---> Prussian white + ferric ions

This tonal reversal is the phenomenon of ‘solarisation’ first observed
and named by Herschel. It is actually desirable for making a print-out
image, because it can ultimately yield a higher maximum density: the
self-masking action by the Prussian blue in the shadow regions of a
printed-out image is diminished by the reversal to white, which allows
the ingress of more light and formation of more (white) product. After the
exposure, the Prussian white so formed is oxidised back to Prussian blue,
either slowly by the oxygen of the air, or more rapidly by including a bath
of an oxidising agent, such as hydrogen peroxide or a dichromate, in the
wet-processing sequence:

Prussian white + hydrogen peroxide ---> Prussian blue + hydroxide ions

<<<<<

Just to clarify my post earlier. In my experiments, the peroxide treated and untreated were measured after the same amount of time (24 hours.) So if peroxide did not complete the oxidation, air would have done so after wet processing. Final density was lower in the peroxide case then probably means that there was some bleaching of the Prussian blue going on as well which was irreversible. That is why in my opinion strictly if you can wait for air oxidation, it would be advisable to do so if maximizing the Dmax was the ultimate goal. If "instant gratification" (as Christopher James says) is sought, on the other hand, go for peroxide or dichromate before final wash and dry.

 

[koraks]

Final density was lower in the peroxide case

That echos my experience. I also observed it took about 48 hours for the prints to reach their final state. This is probably quite dependent on environmental conditions.

 

[Fraunhofer]

Fumed silica does help quite a bit. I just apply it with a dry foam roller and the coat like usual, smells like wet chalk (well that's basically what it is)

 

[Fraunhofer]

Example picture, made with fumed silica using Mike Ware's Simple Cyantope, medium contrast

 

[ChristopherCoy]

Fumed silica does help quite a bit. I just apply it with a dry foam roller and the coat like usual, smells like wet chalk (well that's basically what it is)

WHA-HUH? Fumed silica.... that is the absolute first time I've heard of that. What is it, where do you get it, and how does it help?

 

[ChristopherCoy]

Example picture, made with fumed silica

WOW! I'd be extremely happy with that kind of result.