As sleek new smartphones prepared to make splashes at the Consumer Electronics Show here on Tuesday, a California firm was out to prevent water from being the death of them.

Liquipel was showing off a clear coating a thousand times thinner than a human hair that shields smartphones outside and inside from damaging effects of water.

"Water will just run through the machine," Liquipel president Danny McPhail told AFP as he casually tossed an iPhone into a tub of water and watched it sink. "It actually beads right on top of the circuit board and rolls off."

He plucked the unscathed iPhone from the tub and shook the water from the gadget, which continued to work.

About six weeks ago, the Southern California company launched the first public service that let smartphone owners send gadgets in to be coated using the nano-technology.

Liquipel came to CES to close deals with major electronics makers to have protective coating pre-applied to new smartphones.

"Hopefully, the next time you purchase a phone it will already be treated," McPhail said.

"Wine spills, coffee spills, anything like that you are going to be protected," he continued. "I don't want to say a toilet, but that is where 50 percent of smartphone water deaths happen."

Liquipel charges US$60 to coat a smartphone, with shipping adding to the cost.