It's easier to nail down a blob of mercury than it is to categorize the collaborative work of Wendy Woodson and Achim Nowak.

"I would never want to say we do performance art," says Woodson, artistic director of Present Company.

"Our work has fallen in between dance and theater," says Nowak, Present Company's associate director.

"Original theater work," says Woodson, reluctantly offering a label.

"Original performance works," injects Nowak.

"Interdisciplinary performance works," Woodson finally decides. Then: "We don't want to get stuck."

That sentiment sums up the operating philosophy of Present Company, which since its founding by Woodson in 1978 has created and presented productions that fuse dance, theater and visual design, the resulting form defined each time by the idea being explored.

Woodson and Nowak's latest effort is "Visiting Hours," in which six characters become entangled in a series of comic and increasingly unsettling visits with one another and with the members of the staff of a mysterious institution. Developed last summer during a six-week residency at the Yard, a colony for the performing arts on Martha's Vineyard, "Visiting Hours" will premiere Thursday (after a preview Wednesday) at New Playwrights' Theatre, where it runs through Sunday as part of District Curators' ongoing Cross Currents festival.

"This piece happens to be more toward theater," says Woodson, a choreographer and director who teaches at George Washington University. "But it integrates the two vocabularies dance and theater . . . One does not predominate the other."

"The reason I wanted to work with Wendy was, I've seen a lot of theater and the forms are becoming very pat and predictable to me," says Nowak, an actor and director who teaches at New York University.

"We both train a lot in our respective disciplines," says Nowak. "We both have great appreciation for form and structure. It's not like a loose happening from the '60s," he says, aware of the stereotypes that prey on the word "interdisciplinary."

In addition to "Visiting Hours," Woodson and Nowak have since 1982 teamed to create "Five Lives," "Force of Habit" and "A Disappearance." Their objective, says Woodson, is to prompt audiences to view familiar situations in a new way.

"If you see a love scene done over and over again in the same way, you don't look at it anymore," she explains.

At the same time, says Nowak, "by not being overly specific, we leave room for the audience to fill in with their own experience." Present Company's work, he adds, "deals with subtle shades of nuance."

"We're the nuance people," confirms Woodson.

Like most performing arts groups, Present Company depends on grants to survive. "This kind of work will never totally pay for itself," concedes Nowak. Present Company recently received a National Endowment for the Arts grant to create a new collaborative work for the 1986-87 season, but Nowak and Woodson are finding themselves in the new situation of having to look for funding from the private sector. Such fund-raising poses a dilemma for the artist, they say.

"The less money there is available, the higher the degree of selling," notes Nowak. "Right now we are in an era of: How much can we play up to the bourgeois establishment and get money from them."

"There's too much business now in art," says Woodson. Though she acknowledges it is necessary for artists to be proficient in both art and business, "there is a point at which they are incompatible," she says. "It's a very delicate balance -- if you are too much into making money, the purpose of doing art is diminished."

What keeps Woodson and Nowak focused on that artistic purpose, they say, is their work at community-oriented institutions such as the Kennedy Center and the Filmore Art Center here.

"It's where you are reminded of why you are an artist," says Nowak. "It's the source . . . that really matters."

After a year in the making, it comes down to the point where "Visiting Hours" will have just seven performances, then close. "That's the reality of the situation," says Woodson. "And you try to justify that reality by hoping that this piece will open new doors."

"All we want," Nowak begins, then finishes as Woodson joins in unison, "is to be able to continue to work."