Making a UV projector for alt-process prints

[koraks]

Wow, that's really neat! Some kind of vacuum frame that sucks the paper onto a perforated plate would be ideal, yes. Not sure if it's very feasible though.

 

[AndrewBurns]

Here are some bad phone photos of an A3-sized print I just made, will give them a go with coffee toning tomorrow.

Here's the print, using an adjustment curve made with the test print I made earlier today, maybe a little bit on the light side but we'll see how it looks after toning.



For an idea of how sharp the detail is, here's a zoomed up shot of the radio tower (best I could get with my phone camera, but the detail is extremely fine).



The corners are a little blurry because I literally stuck the paper to my garage door with magnets and rolled the projector into place on a trolley!

Another thing I want to try sometime now that I have a working UV projector is exposing some kind of pigmented emulsion coated onto glass from the rear side of the glass.

 

[Ethan Brossard]

Digital projector has made its first real print! There are a lot of quality of life improvements to make to it, but for now it's usable.





This is just after washing so it will darken a fair bit as it dries down. Ignore the very rapid tonal transition from blue to white, cyanotype always seems to do this with these LCD screens, I presume it's some combination of the technique having an abrupt tonal transition and the LCD screens having a pretty high contrast ratio.

This was a 30 minute exposure at ~350W LED power which is about as high as I want to go. Projected image is about A4 sized (smallest I can project). Focused by eye (through UV laser glasses!) and the image is very sharp and contrasty. There's clearly a slight vignette, which is inverted, so the middle of the frame is darker than the edges, but I should be able to compensate for that easily enough.

What I really need to figure out now is how to hold the paper perfectly square to the projector and keep it flat during exposure. I used a combination of tape and clips to hold this small sheet to a plastic board but during the exposure the paper still bowed slightly, probably from temperature change. Some sort of vacuum frame might be the way to go, but I'm not sure where I could put it as I'm kinda space-constrained.

Very nice! the large amount of white areas make sense. The cyanotype process requires a relatively low contrast negative, and these LCDs are very fairly high contrast compared to a film negative.