Scratch-and-sniff

Scratch and sniff technology generally refers to stickers or cardboard items that have been treated with a fragrant coating. When scratched, the coating releases an odor that is normally related to the image displayed under the coating. The technology has been used on a variety of surfaces from stickers to compact discs. 3M invented the technology in 1965, using a process originally developed for carbonless copy paper called microencapsulation.

Scratch-and-sniff stickers became popular in the late 1970s, and remained so through to the mid-1980s. In 1977, Creative Teaching Press produced some of the earliest scratch and sniff stickers. These stickers were mainly marketed to teachers as rewards for their students.

For a time, scratch-and-sniff stickers were used to diagnose anosmia, although this practice later declined.

Utility companies have enclosed scratch and sniff cards in their bills to educate the public in recognizing the smell of a methane gas leak. In 1987, cards distributed by the Baltimore Gas and Electric Company led to a rash of false alarms when the scents of cards in unopened envelopes were mistaken for real gas leaks.

Scratch and sniff is created through the process of micro-encapsulation. The desired smell is surrounded by micro-capsules that break easily when gently rubbed. The rub to release action breaks the micro-encapsulated bubbles and releases the aroma. Because of the micro-encapsulation, the aroma can be preserved for extremely long periods of time.

While there were hundreds of companies that put out Scratch and Sniff stickers, the most well known are the originators Creative Teaching Press (CTP) (who later renamed them Sniffy's in 1980/1981), Trend Enterprise's Stinky Stickers line (which followed directly after CTP), Hallmark, Sandylion, Spindex, Gordy, and Mello Smello.

More recently the BBC reinvented Scratch and Sniff cards with a version that accompanied a new television series 'Filthy Cities'. Viewers were invited to use the aroma cards at home to experience the nasty smells of Medieval London and Revolutionary Paris as they were taken on a journey back in time to the 'filthy cities' of yesteryear. The four aromas included Sewage, 18th Century Tannery, Marie Antoinettes' Perfume and Pong de Paris. The fragrances and scratch and sniff cards were developed by The Aroma Company Europe in Oxfordshire using aroma touch to smell technology.

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Wikipedia