There have been no parades, no letters from the president, no commemorative stamps, no promises from the Smithsonian. But 1985 marks the 20th anniversary of pop technology's bubbling, befuddling masterpiece: the lava lamp.

Historians will catalogue this bizarre objet d'art in the Age of Aquarius, the School of Ronco-co. In an age of sit-ins, love-ins and interpersonal encounters, it was full of strangeness-achieving, meaningful interaction. Then, like headbands, hip huggers and hippies, the light went out.

Now, at age 20, it appears ready to bounce back on the scene. Check these vital signs:

*Jack Mundy, president of Lava-Simplex Internationale, manufacturer of the Lava Lite, reports sales up 40 percent last year, and up another 35 percent since then.

*Lava lamps are available in the national capital area, at stores including Evans and Best distributors.

*On chic Melrose Avenue in Los Angeles, The Soap Plant boutique displays the gelatinous jewels in the window. Their presence gives the glow-ahead to anyone who ever hoped to own a lava lamp but feared they lacked cachet. The store's Heidi Weeks reports that "they are selling really quickly. Adults say, 'Oh, wow! I remember these,' and kids say, 'OOOH WO-OW, these are wild!' "

*Darryn Cray, road manager of Zuma II, a California band formed by two members of Oingo Boingo, maintains "about a dozen" lava lamps on stage for what Cray describes as very "techno-futuristic" performances. Once, after their truck broke down en route to San Diego, the band played sans lamps, and as Cray recalls, "people in the audience were yelling, 'Where are the lava lamps?!'"

*At the off-Broadway Westside Arts Theatre in New York, the current productions are "Orphans," a dark drama, and "Penn and Teller," a comic performance by two magicians. Lava lamps appear in both.

*The lamp makes a cameo appearance in the new Martin Scorsese film, "After Hours." Jeffrey Townsend, set director for "After Hours," said that everyone putting together the 1960s scene that includes a lava lamp "knew it had to be there without it being mentioned."

All this could well send lava fans stampeding to the attic to retrieve their lamps. (While not all garrets, of course, have lava lamps, Mundy estimates more than 2.5 million were sold in the United States. They must be somewhere.)

For those who never knew them, or perhaps blanked out the memory, lava lamps are glass cylinders filled with two indeterminate substances, one sort of liquid, one sort of solid. When the light is turned on, the solid substance glows, melts, splits, bubbles and bumps. That's all.

"We are celebrating a product which is of no real use . . . You can't read by its light," explains Bill O'Leary, president of a local lava lamp club. But he thinks it is "just the thing for apartment dwellers who long for the cheery glow of a fireplace."

But an official at the American Institute of Architects says the lamp's "kinetic sculptural elements constitute an intriguing relief from hard-edged rectilinearity."

An early '70s TV commercial put it another way, hyping the lava lamp as having "a motion for every emotion."

Mundy first saw the light as a student at Marquette University. "There was a store right on the edge of campus, and it had them going in the window 24 hours a day," he recalled. "So you're coming home from a bar at 3 or 4 in the morning and you see these crazy things, so you can't help but stop and watch . . ." he said. "And who ever would have thought . . ."

He had been working for the railroad when his father-in-law, Lawrence Haggerty, purchased Lava-Simplex in 1976 and persuaded Mundy to take over. Chicago resident Adolf Wertheimer had founded the company in 1965 after seeing the lava lamp at a home furnishings show in West Germany and arranging for its American distribution with the English inventor, Craven Walker.

Mundy recognizes strong emotional attachment to the product in some people. "There are a few who are always interested in what we're doing, especially new items," Mundy said. "And I know these people already have 15 or 20 in their homes."

Not everyone has shown such steadfast devotion to the motion for every emotion. Lava Lite sales hit bedrock bottom in the early '80s, but since then have risen again. "It's really nothing we did," Mundy said of the resurgent interest. "It's just the fickle finger of fate."

Mundy recently appeared on a "Today" show segment with shelves full of lava lamps bubbling behind him, and agreed with reporter Mike Leonard that lava lamp owners weren't "beholden to those fickle pronouncements of what's classy and what's not." Though the lamp's oily undulations suggest a life form evolving out of Dippity-do, William Bailey, professor of chemistry at the University of Maryland, gives a more plausible explanation of its function. The light bulb beneath heats the "lava" enough for it to lessen in density and rise to the top of the liquid. When it cools, it becomes heavy again and sinks. According to Bailey, the viscosity of the lava determines whether you have "one big glob or lots of little globs."

The phlegmatic character of some older lamps concerns Jim Mannarino of the Washington Design Center. He suggests buying an electric timer. "Set it to go on an hour before you get home from work, the lava lamp will be able to give its soothing, simple peace as you come in the door."

But 20 years have passed since the first eruption of molten madness. Can we expect to see that same eerie glow shine into the horn-rimmed glasses, white wine spritzers and electric woks of our time?

Only time will tell. But America loves the far-out, the fatuous, and especially the formerly fashionable. The lava lamp -- still strange, still silly, now antique -- fills the bill like "Laugh-In" filled Monday nights.

Let the skeptics sneer. This is America, where citizens are free to lava little nostalgia.