This western Maryland city doesn't have the reputation of a major U. S. tennis capital. What it does have, though, is a small, 52-year-old family business that has helped to change the game of tennis -- Har-Tru Corp.

Har-Tru is the name of a greenish-colored, fast-drying tennis surface made from crushed Catoctin metabasalt rock, refined and blended with gypsum and other binders. A tennis court made from Har-Tru has a soft surface, like natural red clay, but without the disadvantages of clay, which tends to crack and split in hot weather.

The tennis courts at 16th & Kennedy streets NW -- where the D.C. National Bank Classic tennis tournament is played -- are Har-Tru. Chris Evert Lloyd grew up on the Har-Tru courts of Holiday Park, in Fort Lauderdale. The U.S. Open converted its grass courts to Har-Tru for a couple of years.

According to its makers and its users, Har-Tru is a surface that slows the game, gives tennis balls a good bounce, doesn't reflect heat, dries quickly after rain and is easy on the legs. As Tennis Industry magazine Executive Editor Michael Keighley put it, Har-Tru "has almost become a generic name."

The entire marketing and production operation for Har-Tru is directed from what its 35-year-old President Richard Funkhouser Jr. refers to as the "world headquarters" of the company. Actually, it's just a small building holding half a dozen offices, with a warehouse out the back door.

Funkhouser, who is assisted by four other corporate-type staffers, describes himself as the company's "number three salesman." His other duties include writing promotional brochures and traveling to Europe to see what's new in court construction there.

It was European court construction that first piqued the interest of Funkhouser's grandfather in 1930. He was curious to see if he could make a substitute for a European surface that could be marketed competitively in the United States. What worked best, Funkhouser says, was a waste material from the family roofing business. The composition of Har-Tru has remained essentially the same material since then.

The first 40 years were just "building according to need," on the orders of individual court owners, Funkhouser said. But when the tennis boom started in the late 1960s, business doubled, and Har-Tru began installing its surface at about 150 courts a year. Installing a court is a time-consuming process, involving layers of rock and stone, topped by two tons of material per court, all measured and leveled.

Since the late 1970s, business has declined, Funkhouser said. Due to the bad economic times, the company installed only 70 new courts last year, and is counting on 90 this year. But the market for upgrading and maintenance is still there, as courts need refurbishing every couple of years or so.

Funkhouser puts the sales figures, which are split evenly between new courts and maintenance, at "several million -- hardly megabucks." A new court costs $13,000 to $14,000 to install.

Har-Tru does very little advertising, restricting itself to trade magazines, Funkhouser said. "Why spend the money if you don't have to?" he asked, saying his chief marketing tool is "a genuine quality product."

Funkhouser admits to mixed emotions that Har-Tru carries the generic quality. "Yes, it's good for the fact that people are accepting the concept of Har-Tru as a green, clay-type tennis court. But you also lose some identity of what a true Har-Tru tennis court is.

"The ultimate result is that people are willing to pay for it. Other people accept the recommendations of other people," Funkhouser noted.

One example is Stanley A. Hoffberger, managing partner of the Aspen Hill Racquet Club in Silver Spring, which has 13 Har-Tru courts.

He talked to Washington tennis figures such as Allie Ritzenberg and Pauline Betz Addie, and "determined that Har-Tru Corp. , both from construction and maintenance point of view, had a good record meeting their commitment, and therefore I went with Har-Tru."

Another example is New York's West Side Tennis Club, which for many years hosted the U. S. National Championships, known since 1968 as the U. S. Open. The predominant surface at the club was Har-Tru, which installed its first court there in 1936. When the time came to replace the aging grass courts, the club members wanted Har-Tru, but the U. S. Lawn Tennis Association wanted a harder surface, to favor American players.

The club members won, at least until the association moved out into the new tennis stadium at Flushing Meadow, with its hard courts.

Funkhouser's Har-Tru courts cost about the same to install as hard courts, but the maintenance is more expensive. Har-Tru courts have to be watered, day and night, because they play best when moist. They also have to be brushed, and occasionally new material must be put down to fill in "dead spots."

"I like it, I would recommend it. I like the court surface, but there's no question about the fact it's not as economical in the long run as to put in asphalt," Hoffberger said.

Funkhouser said he would like to expand his markets beyond the eastern United States, where it is dominant, to the West. However, shipping is expensive, compared with selling it east of the Mississippi.

And he noted he "has problems getting the surface familiar to people in the Southwest. They are used to concrete and asphalt, and a soft court doesn't appeal to them. There's a level of education to be overcome."

In contrast, players in the Northeast have played on lots of surfaces, and are more amenable to soft courts, he said.

There is talk in tennis industry circles of a new European surface that is covered with loose rubber pebbles, which would have Har-Tru's advantages, without the costly maintenance. Funkhouser has played on those surfaces, but as they are only 1 percent of the market, he doesn't think they are worth investing in at this point.

Besides Har-Tru, there is another company, Robert Lee in Charlottesville, Va., in the soft-court business. Lee calls its product Fast-Dry.

Both firms have one thing in common -- they tap the same mineral resource for their court material. A vein of metabasalt runs from the Carolinas through Virginia, Maryland and into Pennsylvania, according to John Welborn, Lee marketing director.

In addition, both companies service basically the same Eastern market, although Lee does "a tremendous business" overseas, Welborn said.

But the major difference is in the structure of the companies. As Welborn explained it, "They are builders, we are the largest supplier" of court material.

"Our main thing is to sell to contractors," who in turn install the courts, Welborn explained, adding that his firm, unlike Har-Tru, manufactures its own material.