New materials in 20th-century art were introduced to art making from the very beginning of the century. The introduction of new materials (and techniques) and heretofore non-art materials helped drive change in art during the 20th century. Traditional materials and techniques were not necessarily displaced in the 20th century. Rather, they functioned alongside innovations that came with the 20th century. Such mainstays as oil-on-canvas painting, and sculpting in traditional materials continued right through the 20th century into the 21st century. Furthermore, even "traditional" materials were greatly expanded in the course of the 20th century. The number of pigments available to artists (painters, primarily) has increased both in quantity and quality, by most reckoning. New formulations for traditional materials especially the commercial availability of acrylic paint have become widely used, introducing initial issues over their stability and longevity. Pablo Picasso, Georges Braque, Kurt Schwitters, Joseph Cornell and others incorporated paper collage and mixed drawing (materials) with paint to fashion their work. Both Picasso and Marcel Duchamp pioneered the use of found objects as material for paintings and sculpture during the 1910s. In the 1940s Jackson Pollock pioneered the use of housepaint, silver and aluminum paint, duco, and various objects for use in his paintings. In the 1950s Robert Rauschenberg included 3-D elements like tires and stuffed animals as well as using discarded materials like crushed or flattened cardboard boxes. Yves Klein incorporated live nude models and a symphony orchestra in his performance pieces of his paintings. John Chamberlain used crushed auto parts for sculpture. In the 1960s Pop artists Andy Warhol, Claes Oldenburg, Tom Wesselmann and Roy Lichtenstein made art from commercial products, or art that resembled commercial products like television sets, soup cans, brillo boxes, comic books, household furniture and restaurant items among other things. Edward Kienholz made replicas of actual environments both domestic and commercial, while George Segal made life-size plaster figures in settings using real objects and props. Dan Flavin used electric fluorescent lights and ballasts to create sculpture. In the 1970s Frank Stella introduced honeycombed aluminum and glitter. In the 1980s Julian Schnabel made "plate paintings" with broken crockery stuck to the surface and then painted over, Anselm Kiefer and Richard Long used mud, soil or tar in their works. In the 1960s and again in the 1990s artists used excrement notably - the Italian artist Piero Manzoni in 1961 and the British artist Chris Ofili who