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.