How does a scratch and sniff sticker work?

Question

(need a thorough answer)

Answer 1

Before exploring the technology behind scratch-and-sniff paper, we must first examine the very nature of smelling itself. In order to smell something, actual molecules must travel through the air and into your nose. This is kind of unnerving, when you think about it.

Scratch-and-sniff paper, truly a wonder of the modern age, works because of something called microencapsulation technology. This process takes these tiny aroma-generating molecules, known as odorants, and suspends them inside millions of tiny capsules.

These little capsules really are tiny -- one square inch of scratch-and-sniff paper contains approximately 50 million of them. They're created by a patented process owned by the 3M Company.

So how does it work exactly? Basically, a perfume is emulsified, or whipped, into a plastic liquid. This breaks up the perfume (which can smell like anything -- strawberries, root beer, old shoes, you name it) into billions of tiny odorants suspended in plastic.

The plastic is then sprayed onto paper and dried. When you scratch the dried plastic, the odorants are released, and voila -- eau de old shoe!