The range of ways in which concrete can be give an architectural finish is both wide and glamorous. Lumber was the original formwork material and is still used for special finishes. Texture, that is the reproduction of the natural grain effect of lumber, can be achieved either by using specially selected rough boards in their natural state or by mechanically or chemically treating the board surface. Light sandblasting and rotary wire brushing are two of the treatments frequently applied to emphasize grain. These techniques remove the softer fibers of the wood but since they involve an extra process, they also involve an added cost. This also applies to chemical etching. Prolonged exposure to weather causes a natural erosion which improves texture, but adequate supplies of equally weathered board are usually difficult to obtain. From the use of lumber in its natural state we can proceed to plywood finishes. Interesting effects can be created by setting panels alternately, to give a checker-board style of finish, and by using fillets to make the joints an architectural feature. Thin wooden battens, strips, blocks, or sheets nailed to the panel in a desired pattern are a further way of creating exciting recessed features in a surface. Tempered fiberboard, or hardboard, is frequently used as a form liner to give a characteristic finish to concrete, either from its smooth or its screen side. Metal forms also find their place in providing an architectural finish to concrete. Galvanized metal column forms are available which will give a herringbone pattern in concrete columns. Fiber tubes which provide a spiral effect in column surfaces are often used on smaller jobs where repetitive use is not required. Rubber form liners were the forerunners of the present more widely used plastic finishes, yet rubber liners still have a wide field of application for ceiling and wall where it is possible to create a soft, rug-like texture almost impossible to achieve by other means. Complete fiberglass reinforced plastic forms can also be fabricated; usually they are intended for repetitive casting of a continuous architectural feature. The finish they give is, however, one of perfect smoothness.