[Parkchemiker (OP)]

You need fiberglass fleece from a home improvement market. And a transparent polyethylene bag from the supermarket. And a UV-lamp (money tester). Put the fiberglass fleece (a roll) into the plastic bag. Charge up the plastic bag by frictional electricity, perhaps by moving the bag over your hair. Then go into a dark room. Switch on the ultraviolet light and illuminate the fiberglass fleece with the light. Then switch off the light. With a little luck you will see a yellow light coming from the fleece in the bag. But this light vanishes after some seconds. I do not know what the origin of this effect is. It would be interesting to find that out!

[Bored chemist]

Probably phosphorescence.
Did you try it without charging the bag.

[Parkchemiker (OP)]

Glass fiber fleece moistened with water did not show any light in the dark after illumination with ultraviolet light (black light). The water to avoid any static charge of the glass fiber fleece. Glass fiber fleece as a roll is already charged up. The highly insulating glass fibers tend to static charge.