It's probably more common than you think. When I was in college (actually, just down the road from Kenyon at Denison - they were our big rival), I had a friend

It's probably more common than you think. When I was in college (actually, just down the road from Kenyon at Denison - they were our big rival), I had a friend paint a large part of the "Creation of Adam" on her ceiling... in Tide. So, by day, it looked normal. However, by blacklight, you could see it in all its glory. I still don't know how she got the shading right.