While plastics and new synthetic materials are increasingly becoming more popular in the sign industry, the use of wood for signage is still one of the most used substrates used for manufacturing sign graphics. It is one of the easiest materials to work with, and is still readily available at a reasonable price range. Wood is a still favorite, although you would not want to use wood in highly wet and humid environments, with the woods tendencies to warp, split or crack. Here are the techniques used to produce and manufacture these products.
Hand carving / Routing. Messages on wooden signs may be directly chiseled by hand or cut by routing machines, which are computer controlled machine, also known as CAD/CAM. Stencil-cut letters made with a pantograph machine, by which a stylus is made to conform to the outline of the small letters of the stencil. The pantograph Silencil mechanically transfers these small motions into larger identical motions, which guide a router that cuts the wood. There are size limitations on these machines of approximately 3-inch (7.6-centimeter) maximum letter sizes on approximately 24-inch (61-centimeter) wide wooden surfaces. With the new technology of computer-controlled cutters like lasers, plasma, and water jets, with large cutting areas, any type of letter or logo, can be cutout at any size.
Sandblasting: Messages may be sandblasted into wooden signs, as well concrete signs, architectural foam boards or glass, by covering the surface with a rubber masking material, cutting out the characters, and blasting with fine sand. The depth of the letters determined by the softness of the material and the length of time the sand can be sprayed, before it eats through the rubber and destroys the surface. Sandblasting recommended for woods that have a very even grain, like redwood, or else the surface will splinter and edges will be uneven. Size is not a limitation with sandblasting.
Laminating: The most common laminated wood product for signage is plywood. Made from many different types of woods, standard plywood is most made from exterior Douglas fir. Care must be taken to prepare plywood for use as a sign face by filling and sealing all flaws and edges before applying the finish coats. Exposed edges, especially upper edges, should be weather-protected to prevent the wood from warping and delaminating. MDO plywood or medium density overlay differs from impregnated fiber sheet and is bonded to both its sides. This covering eliminates the grain of the wood and effectively seals both major surfaces of the panel. Edges are still unprotected and must be filled and sealed. The principal use for MDO is for highway signs where its durability has been amply proven. There is also a high density overlay (HDO), that may still be available, but is extremely difficult to find. Another plywood material is metal-clad plywood. This product can be obtained on a more-or-less custom basis, some forms are stock items with lumber companies. Made by laminating aluminum, steel, or whatever material is specified, to the two major surfaces of the sign. In stock forms, smooth or pebble-surfaced aluminums are most common. The sheets can be cut to the desired size, but the edges are always exposed and must be filled and sealed. Cladding is available on one or both sides.