Today’s Wonder of the Day was inspired by Tiarra. Tiarra Wonders, “How are scratch and sniff stickers made?” Thanks for WONDERing with us, Tiarra!

Have you ever played with scratch and sniff stickers? They’re not as common as they used to be. If you ask older family members, they probably remember playing with them often as kids.

Scratch and sniff isn’t just for stickers, though! It can be applied to all sorts of things. Clothing, postcards, advertisements, and many other objects can be scratch and sniff.

How does scratch and sniff technology work? It involves treating an object with a microfragrance coating. When the coating is scratched, it sends scent molecules into the air. That’s how you can smell it!

The scratch and sniff coating usually includes an image related to the scent it carries. For example, a scratch and sniff sticker might feature a picture of a banana. When you scratch it, you smell a banana as if you had just peeled one!

Scratch and sniff stickers first became really popular in the late 1970s. They were fun to put on school notebooks and clothing. Advertisers started to use the technology, too. For example, many perfume makers began to use scratch and sniff technology. They coat cards to put in magazines to promote their fragrances.

Scratch and sniff technology actually has uses beyond just fun, though. For example, some utility companies use it to teach people what a gas leak smells like. Researchers use scratch and sniff to help test patients who may be at risk for Alzheimer’s disease. An early symptom is loss of smell, so this can help doctors catch the condition right away.

How do they get the smells to release upon scratching? First, smells are captured in the form of molecules. They’re then distilled into tiny bubbles of liquid. Through a secret process, these bubbles are turned into ink-like goo. This goo is then printed on stickers and other objects. Finally, when the object is scratched or rubbed, the bubbles break easily and release their smells. This process allows the trapped smells to last for many years.

Can you think of any other ways to use scratch and sniff technology? Would you make new scratch and sniff toys? How about books? What other useful applications do you have in mind?

Standards: NGSS.PS1.A, CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1, CCRA.W.4

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