The Dutch concentrated heavily on the "lower" categories, but by no means rejected the concept of the hierarchy. Most paintings were relatively small – the only common type of really large paintings were group portraits. Painting directly onto walls hardly existed; when a wall-space in a public building needed decorating, fitted framed canvas was normally used. For the extra precision possible on a hard surface, many painters continued to use wooden panels, some time after the rest of Western Europe had abandoned them; some used copper plates, usually recycling plates from printmaking. In turn, the number of surviving Golden Age paintings was reduced by them being overpainted with new works by artists throughout the 18th and 19th century – poor ones were usually cheaper than a new canvas, stretcher and frame.