New York designer Joe Doucet has launched a solid birch chair with a silicone tubular backrest that flexes to the shape of the sitter.

Designed by Joe Doucet for Brooklyn furniture brand Maker Anonymous, the Sling Chair appears to be a simple wooden chair, with a backrest painted in white.

In fact, while the legs and seat of the chair are made of solid birch, the backrest is a supple silicone tube that slides onto extensions of the legs.

Friction caused by the weight of somebody leaning back holds the element in place. The flexibility of the silicone means that it shapes to the contours of the body to provide additional comfort and support.

Once the weight of the sitter is removed, the tube simply slides off the chair legs and can be replaced with tubes in alternative colours and textures, making it easy to update.

"Silicone tubing is a standard industrial product which is available off the shelf from many hardware stores in white, black, clear, frosted, yellow, red and blue," said Doucet.

The designer had the idea while teaching his son how to make a slingshot using surgical tubing. "The flexibility struck me as something that could be utilised for comfort in seating," he said.

"After a long study, I settled on silicone as the most suitable material as it had the perfect strength to stretch ratio. It gives just enough to wrap around the body without stretching so much as to offer no support."

Sling was exhibited during New York design week last month, where Doucet also launched a range of marble flat-pack furniture. Other products by the designer include a mirror that makes the viewer look like they're immersed in water.