First there's the receptionist with big hair, a generously filled candy dish on the desk in front of her. Then there are the offices -- vintage wood paneling, 100-year-old cabinets, mellow old brass doorknobs. The only bygone touch that's missing is secretaries with seamed nylons.

And then there are the manufacturing floors. Is this a bubble gum factory? It sure smells like one. Or maybe a plant for Play-Doh? Those endless bins of bright yellow and pink dough look as though it could be.

Whatever, there's something about visiting the Necco factory that evokes the thrill of being a kid again. Maybe it's because it looks like an old basement, filled with pieces of a giant erector set. Maybe it's the mountains of pastel hearts, a temptation to touch, eat or dive into. Or maybe it's just about fun and sugar and a time when all you had to do was Be Good.

Dig Me. Kiss Me. Marry Me. Be Mine. Be True.

Here at Necco, the country's largest maker of conversation candy hearts, there are more than 100 ways to say I Love You.

Including, Yeah Right. That's new this year. And while romantics may Be Disappointed, it fits the criteria.

"They have to be G-rated, nonoffensive and Mother Teresa-approved," says Walter Marshall, King of Hearts, Corporate Cupid or whatever you call a 63-year-old candy executive who thinks up new sayings for one of America's oldest Valentine's Day traditions.

And the sayings have to be short. Remember that if you ever want to send Marshall a suggestion.

"You can't fit the Gettysburg Address on these," he says, pointing to a row of little yellow hearts, just stamped out and beating at 12,480 per minute.

That all adds up to more than 8 billion Sweethearts Brand Conversation Hearts produced annually at Necco's three plants, making it the top-selling candy for Valentine's Day. Box for box, even more than chocolate.

"I call it romance on a budget," says Marshall.

Others call it nostalgic. Founded in 1847, the company that would later be called Necco (short for New England Confectionery Company) is the country's oldest multiline candy firm. In the 1860s, the brother of the founder began printing sayings on colored paper and placing them inside "cockles," crisp candies shaped like scallop shells. In 1902, conversation hearts were born, along with the company's best-selling item, Necco Wafers.

Nostalgic is the operative word here at the factory, a seven-story plant built in 1927 that's surrounded by the campus of M.I.T. During World War II, aside from making candy and war materials for the troops, it served as an air raid shelter, thanks to its 16-inch-thick reinforced-concrete floors.

Indeed, a visit here is like a trip back in time, a fact the Necco folks tend to apologize for, instead of promoting.

They certainly don't apologize for the recipe for making conversation hearts, which is also old-fashioned and simple. Both Sweethearts and Necco Wafers use the same batter -- it's 90 percent sugar, with a dash each of corn syrup, gelatin, gums and artificial colors and flavorings. To put the recipe in perspective, Necco uses 40 million pounds of sugar a year to make the two candies.

This is far from a shiny new plant shimmering with chrome; much of the machinery has been here since the place was built. But Marshall is quick to point out that the equipment has been modified or invigorated with new motors. Maximum efficiency.

The guy in the white uniform and hairnet seems to be working at maximum efficiency at this particular moment. He's banging a funnel with a hammer, trying to get the sugar that's inside to drop into a vat below. Voila. Then he adds a bucket of corn syrup, a pitcher filled with yellow banana-flavored food coloring and a container including gloppy gum arabic. Blades inside the vat turn the mixture into a doughy mass; it's not unlike making pie crust in a food processor.

From there, the 600-pound batches of dough are fed through a chute and squished between rollers. The resulting yellow "blankets" travel down a conveyor belt, get stamped with 80 sayings at a time, then punched into hearts. The Swiss-cheese-like trimmings are recycled back up the chute.

The newly made hearts, now as soft as pliable as clay, go through a drying cycle, which hardens them to teeth-breaking perfection in 45 minutes. Shelf life: five years, after which the flavor dissipates.

The shelf life of the sayings, of course, has been even longer. Many have weathered nearly a century -- except for ones like "You Are Gay," which bit the dust about 10 years ago. Then in the early '90s, in a stroke of marketing moxie, Marshall decided to update them, using his nine grandchildren as his sounding board. Some of the results: www.Cupid. Be My Icon. You Go Girl. Sister Friend. Cool Dude.

Hip, but not exactly warm and fuzzy.

"The year we put on Fax Me, we got a lot of complaints," says Marshall, whose own romantic history includes a wife of 42 years and attendance at nearly 3,500 weddings, when he played the drums in a band ("I've seen everything -- bridegrooms walk out, mothers collapse, fathers drop dead . . . ").

And then, of course, there was the year of Try Me, Buzz Off and Wild One. A bunch of nuns wrote the company to protest.

"But the majority of people like the new sayings," Marshall maintains.

Back in the former president's office, where a pack of Necco Wafers estimated to be 70 years old resides in a cabinet with other memorabilia, there's a photograph of some really old conversation hearts. Maybe the originals.

Those were the days when conversation candies were much more elaborate, cut in the shapes of postcards, watches, baseballs or horseshoes, and the hearts were embossed with curlicues.

The messages were much more elaborate, too. Long sayings could fit on a candy postal card: "Please send a lock of your hair by return mail." "How long shall I have to wait? Pray be considerate." And, "May I see you home after the circus?"

Romance is still not completely dead. Necco gets lots of requests for the conversation heart that says Marry Me. Any number of men have put them in engagement-ring boxes, says Marshall.

Schools use the hearts to teach students about counting and statistics, and Marshall says he gets "hundreds" of Valentine's Day cards from schoolchildren, many of which include suggestions for future sayings.

For a minimum of 3,500 pounds and about $8,000, Necco will do special orders. Religious groups have requested hearts with Jesus Saves. Mercedes-Benz has custom hearts stamped with the model names of its cars. George Bush's campaign gave out Bush '88 hearts when he ran for president, although none were ordered for his bid in '92. "See what happened?" joked Marshall.

It's not just the conversation hearts that have a life outside Valentine's Day. Necco Wafers have been used as everything from communion wafers to poker chips to tokens for the toll booths along Illinois highways. Marshall says they have even been purchased for target practice (when you shoot the pink ones in the dark, they spark).

And Necco doesn't make just hearts and wafers. In fact, including all the different packaging shapes and sizes, its product line consists of 540 items.

Here's how that happened: In 1963, the faltering company was bought from the fourth-generation family owners by the United Industrial Syndicate (UIS), a privately held corporation with assets of $700 million. Necco is its only confectionery company; its main focus is millwork and automotive and truck parts.

The acquisition allowed Necco to grow and eat up smaller candy companies with longstanding old-fashioned brands. As Necco president Domenic Antonellis put it, "If it's a phase, I don't need it."

That's why Necco bought the Mary Jane brand and the Candy House button brand (you know, those colorful dots on paper strips you used to get as birthday-party favors). It acquired the Mighty Malts brand of malted milk balls. And Necco also manufactures Sky Bars, Haviland Thin Mints, chocolate goose eggs and the politically incorrect but wonderfully retrograde candy sticks (formerly candy cigarettes, now without the red "lit" tips). Antonellis, a former engineer for General Motors, has his eye out for other acquisitions among the country's approximately 350 remaining small candy firms. In the meantime, he's hoping the weather isn't inclement this week, since 74 percent of Valentine's Day candy is sold the three days before the holiday.

As for Antonellis, his Valentine is all set. "My wife used to get chocolates -- even though I made them," he says. "Then one year, she said, Hey, wait a minute!' " He pauses. "So now she gets roses." CAPTION: At work in the Necco factory, employees are making sure everyone can have a heart. CAPTION: Necco's "King of Hearts" Walter Marshall, above right, thinks up new sayings.