How does Blu-tack stick, but not feel sticky?

Our fascination with Blu-tack just grows and grows, and so does its sticking power.

Asked by: Hazel D’Arcy, Kent

Blu-tack uses a so-called electrostatic interaction, forming a chemical bond between itself and whatever it’s sticking to. It’s made up of very small molecules and, over time, seeps into microscopic indents in the surface of materials. The electrostatic interaction gradually gives way to that molecular ‘seeping’. Hence Blu-tack doesn’t feel sticky initially, but gets stickier if you handle it long enough.

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.