Image copyright KFC Hong Kong Image caption Appetising shades? Not quite, as the BBC team found out

US fast food chain Kentucky Fried Chicken has taken its motto of "finger lickin' good" food to a literal extreme by debuting edible nail polishes in Hong Kong this week. The BBC's Juliana Liu tried it out.

Fried chicken-flavoured polish in fun, fashionable shades? It sounded too good to be true.

And it was. Sort of.

The polish was delivered to our office in couture-quality packaging in KFC's red and white corporate colours. The product itself was housed in half-ounce square bottles emblazoned with the slogan "It's Finger Lickin Good".

So far, so good. But the colours seemed off.

Fair is fowl

Image copyright KFC HK Image caption What the nail polishes are supposed to look like...

The "Hot & Spicy" flavour came in a trendy burnt orange shade similar to Tabasco hot sauce.

But the "Original Recipe" was a dirty olive green colour with black specks - a far cry from the advertised nude shade.

On closer examination, we found both bottles had expired a few days ago. The green shade had clearly oxidised.

Image caption ... and what the BBC team in Hong Kong got

That makes sense because both are entirely made of edible ingredients: spice blends suspended in starch, with vegetable gum added so they stick to your finger nails for a day or so, according to a spokeswoman at Ogilvy & Mather Hong Kong, the advertising agency behind the polishes.

With no preservatives, each batch - made by spice company McCormick in Singapore - must be refrigerated and lasts for only five days.

Oh, and the instructions clearly state each bottle is good for one-time use only, presumably, because the ingredients are perishable.

The taste test

The spokeswoman assured me the expired polishes were not harmful, so my BBC Chinese colleague Grace Tsoi and I decided to taste them.

The spicy flavour tasted almost exactly like the paste used in KFC's hot & spicy chicken. It definitely lingered on the tongue, but we couldn't detect any fried chicken flavour.

It was same for original recipe polish: nice balance of spice accented by black pepper, but again, no chicken.

Image copyright KFC HK Image caption The models featured in KFC Hong Kong's promotional images seemed to enjoy it much more

What about their performance as nail polish?

The orange shade was thick but performed well, with minimal drag on the nail surface.

The colour, though, was extremely transparent and not true to bottle. Not even two coats would get me there.

The green shade dragged quite a bit. After it settled down, it clumped in an unappetising way. Major polish fail.

'Not elegant to lick fingers'

The two flavours have been promoted heavily by KFC Hong Kong on social media, but aren't available to the general public.

"At the moment, we're not mass producing it," said the spokeswoman. "We are only giving previews to the media to test the market reaction."

When Grace polled people on Hong Kong's busy streets, she got a wide variety of responses.

"I don't think that eating nail polish is a good idea. I don't think it's elegant behaviour for women to lick their fingers," said Crystal Zhu, a 27-year-old tourist from mainland China.

Image caption Ms Zhu thought the polish would be "inelegant"

Lily Wong from Hong Kong said she'd love to try it.

"It is an innovative idea," said the 17 year-old. "I have never heard of anything like this before… It will be fun to paint nails with my friends."

Image caption Ms Wong gave the idea a thumbs-up

"Some people on a diet may use it," said Twinkle Leung, an 18-year-old student, who believes the nail polish may help quell cravings for fried chicken.

Image caption Ms Leung thought it would help dieters, but her boyfriend thought it was "unhygienic"

Ogilvy said the concept was being floated in Hong Kong because its local team came up with the idea.

And Hong Kong customers seem more enamoured by limited-time offerings, rather than the two stalwart flavours embodied by the polishes.

Judging by the response on social media, the promotion is working, even if the polishes aren't entirely what has been advertised.

Many have expressed incredulity and curiosity, while others were repulsed. "So gross," said Facebook user Crystal Lou, while another called Brian Fung suggested a friend try it "so you can taste (fried chicken) while being a vegetarian."

Additional reporting by Grace Tsoi