This method describes procedures for identifying the wire side of paper made on a fourdrinier paper machine with a single wire or forming fabric. It is not always possible to identify the sides, particularly with coated and other surface-treated papers, papers made with certain multiply papers made from well-beaten rag stock, and specialties made with some variation from usual papermaking practices. Nevertheless, if any one of the following procedures gives a clear result, identification is established. These procedures are not applicable to paper made on cylinder, twin-wire, or other special machines.