Glowing in the dark

I went with friends to go and see authors of a book about the Sunday Post's Broons family - Knit your own Broons. A great wee afternoon with lunch and a wander round various shops to shop for craft things. 

(I changed the picture since I'd posted about this paint...)
A friend asked on Facebook the other day for suggestions as to where she'd get glow in the dark paint that could be used outside.  I didn't find outside paint but I did find this in a pound shop! 
I don't think it's for a Halloween project, so I'm intrigued. And also think I want some. Putting Reflective paint on my (black) gate posts will mean I can see them easier to reverse in.  I might be asking her where she finally gets it!