xsd:string An Agent alters some Material in some useful way by means of some chemical or physical Alterant. Typically, this involves placing a reagent in contact with the Material, or applying heat, pressure, etc. Often a specific Agent and/or Result is mentioned. The Alterant is often incorporated in the target, as in tin.v, galvanize. (The Preserving frame is a special case of Processing_materials, in which the Material is immersed in the Alterant for the Purpose of preventing decay.) Processing_materials is distinguished from Filling in that the Material in Processing_materials is fundamentally altered (often chemically), rather than simply being covered with a different substance. Native Americans dyed textiles with dyes made from cedar strips. Watering cans are often galvanized to prevent rust.