Jalo Porkkala has tested eleven different watercolor and etching papers for cyanotypes and shares the result for cyanotype printing.

We took eleven different watercolor and etching papers that we were able to find in our school’s paper stock – the school is the Satakunta University of Applied Sciences / Department of Fine Art in Kankaanpää, Finland and testing them for printing cyanotypes. We made a few exposure tests using the traditional cyanotype process (blueprint), with a view to finding a standard exposure to produce the maximum “black” for each paper. At the same time we examined the suitability of these papers for printing cyanotype and compared the blue tones the papers could produce.

The classic cyanotype is known to work almost on any paper, and mixing of the sensitizer is simple enough: you only need two chemicals to make two separate stock solutions. This time we didn’t mix them by ourselves but used ready-made solutions by Hopeavedos, a Finnish supplier. We coated the papers with a mixture of the two solutions (see the classic cyanotype formula). None of the papers were given extra sizing.
As we expected, there were no great differences in tone or sensitivity between the sensitized papers. The exposure times to produce maximum tone density varied from 6 to 10 minutes when exposed with our UV-exposure unit from one-meter distance. All samples were exposed in a vacuum frame, partly covering the sensitized areas with blank Agfa CopyJet transparency, hoping to find out something about its UV-transmittance properties.
Below are the results of our little paper survey – we scanned pieces of each paper showing maximum cyano density plus the uncoated paper base (samples shown approximately life-size). In conclusion, our experience is that all of these tested papers could be used successfully in traditional cyanotype printing. However, there are a few papers that print better than the others.

Very good paper for cyanotype. Can produce intensive blue. Nice surface texture.

Both tested Canson papers are our long-time favourites. Prints and clears well.

More textured than Montval. Slightly deeper blue, towards ultramarine. Also the smoother back side works well.

Very hard, white and smooth paper. Works well when not over saturated with sensitizer.

Velvety surface, a little difficult to print. Touching wet prints tends to leave marks.

Very white base, prints deep rich blue, clears well, good paper for cyanotypes.

Both Guarros are excellent cyanotype papers, this one has warmer cream hue.

Etching paper, maybe a little too soft for cyanotype, but it works. You can easily abrade the wet surface though.

Our first favourite paper for cyanotypes from this set. Although not one with highest max densities, it is easy to coat, predictable and attractively textured.
@Heidi Thank you for sharing!
My paper of preference is Fabriano Rosaspina
How do you acidify the paper?
The new Arrche Platine is neutral, it must be acidified before use
I agree with Jean Claude Mougin. Arches Platine has been for cyanotype the best, but some years ago the chemical composition of this paper has changed, in a way that the results with cyanotype aren’t stable as before.
Friede
To have maximum black with cyanotype it is necessary to have an acidic paper. Since 1985 no paper is acidic but neutral or basic, and that is catastrophic. Because i am an old man I am working in palladium and cyanotype only with old paper before 1985. Today the only one acidic paper is the Arches Platines and some japanerse paper.
Mougi
What is the best paper to use in making a paper negative for a cyanotype print? In other words I wish to make a contact print from a paper negative like an architectural drawing. What is the best/least costly paper to use?
your site is awesome, i love it. i have been doing this stuff for years. turning students onto alternative photography. i even managed to teach alt processes as an instructor at the art institute for some very excited graphic design and photo j students, who would have never had the fine art experience of cyanotype and darkroom tricks. i am very encouraged by your site and congratulate you on bringing inspiration to the ever-lurking dinosaurs of photography.