The various combinations of materials in the stock suspension used in the manufacture of paper and board. They include the fibrous materials (pulp), i.e., the rag, chemical wood, mechanical wood, esparto, cotton fiber, linen, or other pulps, sizing materials, i.e., rosin, alum-rosin sizes, etc., various additives, e.g., wet strength agents. fillers of various types, e.g., retention aids, or loading materials, and dyes. (17 , 58 , 72 )