Super fun; I used to do this and make gifts for friends and family. If done well, on acid free paper, and kept out of bright sunlight, they can be relatively archival.

The linked article shows making cyanotype from outline if flowers, but far more fun IMO is digital negatives. There is a link to this at the bottom of the article, but I’ll share something I found that helps tremendously that wasn’t mentioned AFAICT.

When printing your digital negative, in addition to inverting your greyscale /B&W photo, you’ll want to adjust the curve, because the cyanotype will expose nonlinearly.

The best way to find the curve given your chemistry, photo, sunlight/latitude, etc. is empirically.

So, I recommend in photoshop/GIMP/whatever to generate a series of greyscale bars from #000000 to #FFFFFF, with perhaps a dozen or more steps. Put this alongside your image, then invert, and make a test print. You can then observe the nonlinear development of color and adjust the curve (remember, inverted) to apply to your final image for printing.

Probably I can think of more but this is already kind of lengthy on mobile :)

Freestyle has some more information, and a step wedge test file you can print to help calibrate. https://www.freestylephoto.biz/alternative-process/making-di...

There is a chemist from the UK that has done extremely impressive work in this field and offers a lot of more technical informations (https://www.mikeware.co.uk/mikeware/downloads.html).

A couple of mine, "new cyanotype" sensitizer brush-coated on arches platine paper, digital negatives printed on Pictorico OHP film from scans of analog negatives:

https://i.imgur.com/ISWlz81.jpg

https://i.imgur.com/xYRUrKk.jpg

NileRed did a fantastic series on Prussian Blue, the pigment that ends up being created with cyanotypes, and ended on making his own cyanotypes from scratch <https://www.youtube.com/watch?v=hYqn8CO2P3E>

His entire channel is just fantastic in-depth demonstrations of various interesting chemical lab processes; It highlights of my favorite kinds of internet corner: passionate and in depth niche content

His channel is great, but I wouldn't suggest learning from his episode on cyanotypes; it's interesting to watch but he does a lot of suboptimal things.

Website seems to be down, here's a mirror: https://web.archive.org/web/20210116152552/https://parallaxp...

https://archive.is/i8xhn

You can make "digital negatives" by printing onto transparency sheets, but be aware that laser printers don't seem to do a good enough job for a nice sharp image--it seems that inkjets are your safest bet.

Pictorico OHP film is the best for this. Yellow ink is usually more UV-opaque, so I suggest using that to improve dmax.

There are ready-made toning curves to linearize the results, but to obtain reliable results a calibrated workflow is necessity in practice.

Also good tonality with digital negatives can be counter intuitive because the spectral response of various media is not uniform and printer inks are not necessarily pure colors.

Yes, definitely ink jets on transparency! I have another. Moment at top level on curves and exposure also.

And if you are a weird old guy like me, you can use your 4x5’s.

Cyanotypes are so much fun. Had good results printing digital negatives on transparencies. It’s easy to do and watching the picture appear is very rewarding. Here’s some examples: https://www.kevan.tv/art/cyanotypes/

Worth noting that Potassium Ferricyanide, one of the two active chemicals in this process, is quite toxic and poses significant environmental hazard [1]. I might suggest Anthotype [2] instead, which is just Vodka, Turmeric, and Borax. The resulting print is a lovely red/orange rather than blue, and there's significantly less concern over chemical cleanup & disposal. Also the exposure is long enough that you don't even need a dark room!

[1]: https://pubchem.ncbi.nlm.nih.gov/compound/Potassium-ferricya...

[2]: https://www.youtube.com/watch?v=gmQxqE61lOg

Just don't store your potassium ferricyanide for cyanotypes, too close to the sulphuric acid you use as a photgraphic bleach. They don't do too well together.

Could you do something that looked like a cyanotype?