Squishy feat

Invented in 1956, Play-Doh has wedged its way into children's fingernails and living room carpets every since. Now, the company has convinced the US trademark office that consumers across the country specifically link the Play-Doh smell to Hasbro's neon modelling clay.

That alone is a squishy feat. "The law tries to make it relatively difficult," said Polk Wagner, an expert on intellectual property law at the University of Pennsylvania Law School. "Not everybody can say they have the world's most distinctive scent."

According to the patent and trademark office, scents that serve a utilitarian purpose - like the scent of perfume or an air freshener - serve a function and cannot be registered as trademarks. The guidelines note that the "amount of evidence required to establish that a scent or fragrance functions as a mark is substantial."

As for patents, scents can be patented and generally fall into categories for cleaning and perfume compositions.

Eau de Play-Doh

Scents, colors and sounds can be trademarked, so long as the companies or individuals behind them can prove that consumers have strong associations with them. Companies can provide surveys and studies demonstrating how consumers link certain smells or sounds with a particular product. Still, trademarks like logos or images - like the Nike swoosh - might carry those ties more obviously, Wagner said.

According to the patent and trademark office, other active trademarks for scents, smells, odours and fragrances include the "flowery musk scent" used in Verizon stores and a bubble gum scent used for shoes and flip flops by the retailer Grendene.

Cherry, grape and strawberry scents were trademarked for lubricants used for land and water vehicles by Manhattan Oil. And jewellery company Le Vian trademarked a chocolate scent for its stores.

Wagner said Hasbro's trademark could be used to cut down confusion for consumers if other companies or individuals make products with a scent similar to Play-Doh's. And it could provide Hasbro with an edge over competitors that sell toys "that are similar in function to Play-Doh, but are not called Play-Doh," Wagner said.

Before the scent's trademark, Hasbro debuted a Play-Doh fragrance in 2006 for the toy's 50th birthday. The "eau de Play-Doh" rolled out just before Mother's Day and came in a clear, 1-ounce spray bottle.

But not all one-time toddlers could get behind the Play-Doh scent, as evidenced by consumer reactions on Twitter.