The light weight and toughness of clear plastic sheet qualifies it for many jobs formerly held by glass. Materials in this category include acrylics, cellulosics, polyarylates, polysulfones and polycarbonates. Despite the durability of these materials, however, their surfaces are softer than those of glass, making them more susceptible to hazing by surface abrasion and to damage by scratching. But progress is being made, and more abrasion-resistant materials and surface treatments are being developed.