CHICAGO (Reuters) - Use superlatives. Tell buyers they won't pay full price. Offer free stuff if they buy now. Keep up the patter. Never stop moving.

The hard sell has been around since ... well, forever. And the Popeil brothers may have perfected the pitchman's art.

The Popeils -- Sam, Raymond, and Sam's son Ron -- became millionaires hawking an endless stream of household gadgets that every home anywhere seemingly had to have.

Many will remember the vegetable-chomping "0-Matics": the Veg-O-Matic, the Chop-O-Matic, the Dial-O-Matic, the Slice-O-Matic, the Peel-O-Matic, the Whip-O-Matic. There were the battery-powered "cordless electrics": the Miracle Broom, the Garden Trimmer, the Smokeless Ashtray. And there was the silly gadgetry: the Pocket Fisherman (a compact fishing rod), the Trimcomb (haircuts), and Mr. Microphone (for projecting one's voice over the radio).

The Popeils kept coming up with gadgets and Tim Samuelson kept collecting them at auctions and from basement sales.

Samuelson's collection of more than 150 devices are part of a two-month exhibition on display through mid-May at Chicago's Cultural Center, a determinedly low-brow show compared to a photography exhibit upstairs and the museum show of gem-like Rembrandt prints on view nearby.

Out-of-town visitor Joel Dain skipped the Rembrandts, but his eyes glisten at the memory of the Dial-O-Matic he bought four decades ago from a New York pitchman. Dain recalls the episode because the gadget is still in his kitchen, slicing and dicing tomatoes and potatoes.

"It still works, though pieces of plastic have broken off," Dain says, adding the steel blade never needs sharpening. Doesn't he make room for modern appliances? "I have a microwave oven, but I have to keep it in the basement because my wife is scared of it," he says.

The gadgets made under the Popeil and Ronco names invariably still work when Samuelson finds one. He demonstrates a Veg-O-Matic's durability by standing on it.

He pours cream into a Whip-O-Matic -- "faster than any electric mixer because it has Popeil's special planetary action," he proclaims, displaying the whirling, rotating plastic blades -- and after a few turns of the handle he upends the whipped contents over his head without spilling a drop.

PITCHING ON THE BOARDWALK

The late Popeil brothers -- Sam and Ray -- honed their marketing skills amid the crowds strolling New Jersey's coastal resort boardwalks where pitchmen barked to attract customers.

To hear Samuelson talk, he might prefer roaming the boardwalk himself, but spends workdays instead answering questions in his job as a Chicago cultural historian. But the jovial architecture buff, who stores his gadget collection in his apartment, says his pitch pales against the master of the late-night infomercial, Ron Popeil, now 69.

"In five minutes, I can sell anything," Ron Popeil is quoted as saying in Samuelson's book of Popeil-ia, "But Wait! There's More! The Irresistible Appeal and Spiel of Ronco and Popeil" (Rizzoli, 2002).

Flip the TV channels past midnight and one is sure to hear Popeil's dulcet tones coaxing buyers for his Rotisserie oven -- with free barbecue gloves and a recipe book if you buy now.

And over the years, the Popeils sold millions of gadgets in the United States, but also in Canada, Japan, the United Kingdom and other countries, Samuelson said.

The Veg-O-Matic originally sold for $9.98 (later reduced to $7.77) and the Pocket Fisherman for $19.95. Since so many were sold and because they are so durable, the gadgets can sometimes be obtained cheaply -- so Samuelson's collection may not have appreciated much.

No matter. Samuelson revels in this slice of Americana, though he says Popeil urged him to quit demonstrating the Slice-O-Matic. "He said 'It'll take your arm off."'

Ron Popeil prefers tinkering in his Beverly Hills kitchen much like his father, Sam, whose family would often find him fooling with his latest gadget amid the clutter in his kitchen, Samuelson says. Sam created the Pocket Fisherman after being accidentally poked in the eye by a child's fishing pole.

Sam's brother Ray oversaw their factory after they moved to Chicago in 1945, occasionally making televised sales pitches without showing his face. In order not to distract viewers from the product, he shaved his arms and performed a manual ballet, laying out sliced vegetables like a Las Vegas card dealer.

A documentary showing at the exhibition recorded 1950s-era pitchmen reeling in customers at Chicago's legendary open-air Maxwell Street flea market, which Samuelson narrates: "'Here, here's a free sample.' Keep it moving. Build up the product. Use superlatives: 'miracle product,' 'fantastic,' 'amazing.' Don't say the price until the end -- that's 'the turn.' Show people the money (from previous sales). Tell them you can buy it in the store for this price, then make the pitch at a lower one."

Nowadays, gadgets are unveiled with slick marketing techniques inside Chicago's cavernous convention center at the housewares industry's annual show.

Ron Popeil learned to pitch by studying the Maxwell Street regulars.