the-BA : Chewing gum

By Wendy Barnaby

A new chewing gum which is easy to remove from pavements may shortly see off the revolting hazard of old gobs of gum stuck underfoot, the BA Festival of Science heard in York.

Professor Terence Cosgrove of Bristol University and his colleagues have developed the new gum, currently called Rev-7.

His new, secret polymer ingredient gives the gum a film of water around it.
"That's one of the reasons it’s easy to remove and in some cases doesn't stick at all," he said.

Working through his spin-off company Revolymer, Cosgrove sent six people out to various places in North Wales and Bristol to chew different gums for 20 minutes, stick them on paving stones and see whether they'd degrade.

"Basic chewing gum, without our ingredient, is still there after eight days," he said. "The commercial gums are similar, although they’ve spread a bit on the paving stones. And ours has gone."

Cosgrove held up two vials of water containing chewed gum. After seven weeks, the commercial gum was still there, with algae growing on it.

The new gum had dispersed into the water as a fine, white powder. "It will degrade in the environment," said Professor Cosgrove.

"All chewing gum contains polymers and plastics. Most commercial chewing gums contain the same polymers you'd find in car tyres. That's where they get their elasticity and adhesive properties.

"Chewing gum is one of the best adhesives we have," he said.

Cosgrove and his colleagues have done various tests of the new gum. In the heroic tradition of human guineapigs, Jenny Pettman, daughter of Revolymer’s CEO, agreed to see if the new gum stuck to her hair.

"We stuck one commercial gum on one side of her hair and ours on the other, then tried to get it out. We pulled as much as we could and tried to get as much as possible of [the commercial gum] out. Eventually we had to cut the hair off.

With our gum, we took some standard shampoo and rinsed it and were eventually able to comb it off."

"We’ve had 20 people taste this gum, and a series of people estimate how good a chewing gum is for the mouth: does it blow bubbles; does it stick to your teeth; a whole range of seemingly-strange industry specifications. Ours is amongst the top in a totally blind test."

The new gum will, however, stick to some materials.

"Leather shoes are a problem. You’d need water and a surfactant to get it off leather-soled shoes," said Cosgrove.

The gum is currently going through official EU safety tests. "We have to have the polymer we’ve added passed as an acceptable food product. We’re hoping that by Christmas we'll have full approval," he said.

The new gum, which is being made in mint and lemon flavours, is expected to be available early in 2008.

Read more news coverage in New Scientist, the Scotsman, the Telegraph and the Independent.