Everyone needs a mentor. For William Johnson, a black artist from Florence, South Carolina, it was a teacher at the National Academy of Design in New York, who raised money to send him to Europe in 1926.

In France, Johnson met and married a Danish artist. They moved to Kerteminde, a small Danish fishing village from which he traveled in Denmark and Norway and painted the rich, expressionistic landscapes -- fjords, midnight suns, mountains and harbors -- that go on view Friday at the National Museum of American Art.

"William H. Johnson: The Scandinavian Years" is a show of 46 densely colored paintings, subtler watercolors, prints and drawings that mark a distinct period in Johnson's life -- probably his happiest years. When his wife died in 1943, the artist spent a summer with his mother in South Carolina and, returning to New York, worked as a laborer. Years later, in his mid-40s, his brain was damaged by paresis; he was institutionalized on Long Island in 1947 and never worked again. Johnson's work fell between the schools -- too conservative to be avant- garde and vice-versa. When he died in 1970, he hadn't made much of a splash on the American art scene.

In France, before his Scandinavian period, he produced Soutine-influenced, bold- colored paintings. Upon returning to the U.S. in 1938, he leaned toward folk art, drawing on spirituals and childhood memories, calling himself a "primitive," art school notwithstanding. In between, in the north countries, he painted with emotion. Wavy brushstrokes and unrestrained, thick swatches of color mark the zigzagging buildings and dancing mountain blossoms. The oils, some on burlap, make sense once you realize he was in love. Yet his draftsmanship was assured, and the watercolors show strong technical ability.

In addition to this show, five of Johnson's paintings from the '20s and '30s are on view indefinitely in the same museum's Lincoln Gallery, including a penetrating self-portrait done sometime in the early Twenties. The four others are "primitive" with a vengeance. Only the signatures show they're all by the same artist. WILLIAM H. JOHNSON: THE SCANDINAVIAN YEARS" -- Through November 28 at the National Museum of American Art.