For a short time in total darkness it actually is pretty bright. Obviously my phone’s camera automatically wound the exposure up quite I bit when I took that picture in the dark, though. That was without any special charge-up, just an hour or so of exposure to the largely LED based lighting in my office with it lying face up on my desk.

This is the Overture brand glow PLA.

I whacked it with my little Lumintop single AA flashlight last night and left it sitting on my bedstand, and found that it was still quite visibly (albeit dimly) glowing by dawn the next morning.