Modern interior design derives its influences from the modern art movement that preceded modern design. In painting, Modernism began with the Impressionists and others who used abstraction. Modern interior design grew out of the decorative arts, notably Art Deco, in the late 19th and early 20th centuries. It reached its peak in the 1950’s and 1960’s, which is why designers and decorators today may refer to modern design as being “mid-century.” Shapes: One of the most important elements in modern interior design is form. Modern design uses geometric shapes, including rigid squares and rectangles along with smooth curves (“clean lines”). Perfect circles and ovals are also common in modern interior design. Modern interior design is also generally very simple and even minimal (see: Minimalist), with few ornamental flourishes to interrupt the even, unbroken lines and flat surfaces. Materials: Modern interior design makes use of many materials. Wood and plastic are common, though designers often paint over wood with an opaque finish to cover the natural wood grain. Some designers do use natural wood as an organic contrast to more artificial shapes and materials. Glossy metals, such as stainless steel, are among the signature materials in modern interior spaces. The metal may be used for anything from the legs of a chair to the body of a lamp. Modern interior designers also make use of glass and plastic for their smooth, even surfaces.