Not that it’s the kind of thing that pops into your head often, but if you ever do think of a cyanotype print, it probably doesn’t conjure up thoughts of modern technology. For good reason — the monochromatic technique was introduced in the 1840s, and was always something of a niche technology compared to more traditional photographic methods.
The original method is simple enough: put an object or negative between the sun and a UV-sensitive medium, and the exposed areas will turn blue and produce a print. This modernized concept created by [Gabe] works the same way, except both the sun and the negative have been replaced by a lightly modified resin 3D printer.
A good chunk of the effort here is in the software, as [Gabe] had to write some code that would take an image and turn it into something the printer would understand. His proof of concept was a clever bit of Python code that produced an OpenSCAD script, which ultimately converted each grayscale picture to a rectangular “pixel” of variable height. The resulting STL files could be run through the slicer to produce the necessary files to load into the printer. This was eventually replaced with a new Python script capable of converting images to native printer files through UVtools.
On the hardware side, all [Gabe] had to do was remove the vat that would usually hold the resin, and replace that with a wooden lid to both hold the UV-sensitized paper in place and protect the user’s eyes. [Gabe] says there’s still some room for improvement, but you wouldn’t know it by looking at some of the gorgeous prints he’s produced already.
No word yet on whether or not future versions of the project will support direct-to-potato imaging.
Robert Murray Smith has also been doing this but without modifying his printer. Being British he also fixes the image (they eventually fade in the light) by the expedient method of dunking it in some tea. https://youtu.be/GluNgAFQVkY
cyanotype does not fade or need to be fixed, assuming you properly wash the print to a neutral or slightly acidic ph. same blue as in denim pants.
tea is used for toning, will change the blue to a more black/grey tone.
UVTools has a Lithophane generator and can directly generate the slices from an image file, no need to muck about with scripting or anything else.
Best to fix your contrast curve first in photoshop as cyanotype is rather non-linear. There’s also a minimum exposure so you want to adjust your very bottom layer to account for it.
To calibrate and linearize exposure it’s best to print some test squares, I did an 8×8 matrix so 64 squares and each 4 layers high which will map 0-255, then you linearize that and apply a curve on your image in photoshop. A lot to explain here but there are good guides to doing this with digital negs for alt printing, search for tools like Chartthrob to start down that rabbit hole.
I played with this a year or more ago now, works quite well – I got the idea from elsewhere else btw. so not my claim to fame.