Born in Montreal, Riopelle began drawing lessons in 1933 and continued through 1938. He studied engineering, architecture and photography at the école polytechnique in 1941. In 1942 he enrolled at the École des beaux-arts de Montréal but shifted his studies to the less academic école du Meuble, graduating in 1945.
He studied under Paul-Émile Borduas in the 1940s and was a member of Les Automatistes movement. Breaking with traditional conventions in 1945 after reading André Breton's Le Surréalisme et la Peinture, he began experimenting with non-objective (or non-representational) painting. He was one of the signers of the Refus global manifesto. In 1947 Riopelle moved to Paris and continued his career as an artist, where, after a brief association with the surrealists (he was the only Canadian to exhibit with them) he capitalized on his image as a "wild Canadian". His first solo exhibition took place in 1949 at the Surrealist meeting place, Galerie La Dragonne in Paris.
In 1959 he began a relationship with the American painter Joan Mitchell. Living together throughout the 1960s, they kept separate homes and studios near Giverny, where Monet had lived. They influenced one another greatly, as much intellectually as artistically, but their relationship was a stormy one, fueled by alcohol.The relationship ended in 1979. His 1992 painting Hommage à Rosa Luxemburg is Riopelle's tribute to Mitchell, who died that year, and is regarded as a high point of his later
The presence of long filaments of paint in his painting from 1948 through the early 1950s has often been seen as resulting from a dripping technique like that of Jackson Pollock. Rather, the creation of such effects came from the act of throwing, with a palette knife or brush, large quantities of paint onto the stretched canvas (positioned vertically).
Riopelle's voluminous impasto became just as important as color. His oil painting technique allowed him to paint thick layers, producing peaks and troughs as copious amounts of paint were applied to the surface of the canvas. Riopelle, though, claimed that the heavy impasto was unintentional: "When I begin a painting," he said, "I always hope to complete it in a few strokes, starting with the first colours I daub down anywhere and anyhow. But it never works, so I add more, without realizing it. I have never wanted to paint thickly, paint tubes are much too expensive. But one way or another, the painting has to be done. When I learn how to paint better, I will paint less thickly
A third element, range of gloss, in addition to color and volume, plays a crucial role in Riopelle's oil paintings. Paints are juxtaposed so that light is reflected off the surface not just in different directions but with varying intensity, depending on the naturally occurring gloss finish (he did not varnish his paintings). These three elements; color, volume, and range of gloss, would form the basis of his oil painting technique throughout his long and prolific caree. Wikipedia