UV Reactive Putty

A bouncy putty that shows its true colour in the sun or under UV light!  The putty contains leuco dyes that vividly change colour when exposed to UV.
A fun reversible change that even Einstein could have used to demonstrate his science.

Age:  5 to 12 years
Included:  25g putty of one colour + UV light source in metal tin

No Instruction sheet is included.  Please use the Instruction sheet below, if required.