Luminescent paint with Promethium at daylight.

 
Promethium paint in the darkness. Sample on the left photo taken shortly after the exposition on the daylight, Paint lighting mostly due to the phosphorescence. Photo from the right made after keepeng of the sample in the darkness for 2 day. No phosphorescence, only radioluminescent lighting. Exposition is 2.5 sec for both photos.

 
Promethium paint in the darkness, photo made at 30 sec exposition (and 2 days keeping in the darkness).