If you don't remember what formwork was like before plywood, take a look at the exposed concrete in historic structures, and you'll see the marks of hundreds of boards that made up the form faces. The advent of plywood with dependable, waterproof glue was a revolutionary development for form builders, and today grade B-B plywood, manufactured to established U.S. product standards, is a household word in the industry. Where a smoother finish is needed, high-density and medium-density overlaid (HDO and MDO) plywoods are available, manufactured to the same voluntary product standard (PS 1-95 Construction and Industrial Plywood).
With plywood as a base, several manufacturers have developed high-performance forming panels by coating standard plywood with materials such as polyethylene and glass fiber- reinforced plastic. But the innovation hasn't stopped, and here we focus on some of the further product developments—panels of oriented strand-board (OSB), composite panels of metal and plastic, and new coatings for plywood. Some of these recent developments include the use of readily renewable resources and plans for recycling nonrenewable materials.