SAN FRANCISCO -- Ask Phil Broughton if he has ever dismantled a nuclear bomb, and he will pause, clasp his hands around his thick red beard and give a couched answer.

"Not that I can talk too much about," said Mr. Broughton, a radiation safety specialist at the University of California, Berkeley.

What he does want to discuss is beer: specifically, a stein crafted from lab equipment normally used to keep liquid nitrogen so cold it doesn't boil off into vapor. Beer will stay perfectly frosty for days if left alone in the vessel, he says. That discovery has turned into a business for the 34-year-old, who began selling high-tech mugs for as much as $375 last year.

"The primary buyers have been coming out of academic and research institutions, but by no means are limited to that," Mr. Broughton said. "I've had bankers, lawyers, architects, IT folks and, in one case, a Coast Guard lieutenant."

He first realized he had something valuable while celebrating Oktoberfest at a bar in Ben Lomond, Calif. He poured a pitcher of beer into one his steins, keeping it cold for hours. The bar owner told him he could get hundreds of dollars for his invention, showing him a hand-carved German stein that cost $3,000.

Mr. Broughton has worked at Lawrence Livermore National Laboratory and at the Amundsen-Scott South Pole Station. He acted as the bartender during his stay at the frigid lab, specializing in removing the water content from cocktails by dumping liquid nitrogen into the glass, he said.

He decided to fashion his first "stein of science" in September, during one of the mandatory furlough days that all California state employees take because of budget cutbacks.

The steins are made from a piece of lab equipment known as a Dewar flask. It was invented more than a century ago by James Dewar, a Scottish chemist and physicist who was the first person to produce hydrogen in liquid form. Mr. Dewar didn't patent his invention and lost out on a commercial opportunity when a German company called Thermos started manufacturing a similar product in 1904.

Mr. Broughton's steins are made with more precision than a typical thermos. That means liquid, whether beer, coffee or tea, will retain its temperature much longer. Empty, they weigh between 8 ounces and 5 pounds.

Anthony Langford, an instructor at Bank of America in San Francisco, uses his stein as an icebreaker during training sessions.

"It's sort of a piece of art," he said. "So I have a talking element to say, 'Who can guess what this is on my desk?' The problem is that it works really well and people try to swipe it."

Mr. Langford, 33, likes to show off the stein's effectiveness by pouring piping hot coffee in it in the morning, then removing the cap six hours later to see steam rise out of the cup.

"I have had executives who come from the East Coast that look at it, and eyeball me, and I say, 'Don't touch the cup, back off.' "

Mr. Broughton has sold at least a dozen of the steins and is receiving more inquiries after being featured on Uncrate.com, a website for men, and social-trend site Thrillist.

Sales of the steins have just gone international: Mr. Broughton shipped one to a Northwest Investment Management employee in Hong Kong.

Washington correspondent Daniel Malloy writes the "Pittsburgh On The Potomac" blog exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.