I guess I spoke too soon. The CMC formula is great though. The resolution is basically photographic.
https://lemmy.world/post/26591859
For use on plastics you need the sizing that I proposed on there. For regular paper I just noticed that that you shouldn’t use peroxide to develop anything. First of all there’s actually no hardening due to free radicals necessary. But I noticed that with bad paper, it will immediately turn all blobs of ugly gloppy blue. All that is needed is to remove the yellow sensitizer, so start with water only. But I am thinking that a better developer would be a quick wash in dilute HCl, citric, acetic, oxalic or sulfamic acid.
This is great cheap watercolor paper: https://a.co/d/aNkZqji It works fantastically out of the bag. It comes in a very losely packed thin plastic. Some complain that it comes damaged on the corners but that was not the case for me.
I’ve tried an old batch of nenah 94lb paper? And that worked well with less surface waviness. Photo paper blued badly on peroxide but maybe it will work with dilute acid.
It’s really easy to focus the projector. Just do the same coating on a focusing paper but use fluorescent yellow (biggest response to UV). The paper will glow brightly with the image. You can use clear poly carbonate safety glasses to look at the image while focusing the UV.