Here are two quick tests with Lumi’s photosensitive blue dye.
First, I painted some onto a piece that was printed several days ago and fully dried and cured. This was immediately problematic because the dye is quite thin and beaded up on the smooth print.
Second, I mixed some of the dye into some resin straight from the bottle onto the back of a piece of support from a previous print. This new liquid turned into a milky, off-white substance.
I exposed them both in a UV exposure box for roughly 5 minutes.
Results: the painted on dye worked great, where it stayed on the printed piece. However, 95% of it washed off after a run under a bathroom faucet. The milky substance turned into a yellowish-brown thick liquid, not unlike phlegm (yuck) and did not harden.
So - photosensitive dyes are a #FAIL.