separated wood fibers used in manufacturing paper and allied products —see defibration, pulpwood; pulp types include the following:

—chemical pulp a pulp resulting from the reduction of wood or other fibrous material into its component parts by cooking with various chemicals, typically under pressure, in such processes as sulfate, sulfite, etc.

—dissolving pulp a very pure, fully bleached chemical pulp with a high alpha cellulose content, made specifically for dissolving in suitable solvents for regeneration to form cellophane, rayon, etc., or processing further to form acetate, nitrates, etc.

—elemental chlorine-free (ECF) pulp wood pulp that is free from elemental chlorine

—kraft pulp a strong papermaking fiber produced by the kraft process in which the principal cooking agent is a mixture of sodium sulfide and sodium hydroxide—synonym sulfate pulp

—mechanical pulp any wood pulp manufactured wholly or in part by a mechanical process in which fibers are separated by grinding or refining —note groundwood pulp is a type of mechanical pulp obtained by grinding wood against revolving cylinders so that its fibers or fiber bundles are separated but remain chemically unchanged; groundwood pulp is used mainly for newsprint; chemigroundwood pulp is obtained by treating wood with chemical solutions under pressure before grinding

—sulfate pulp —see kraft pulp

—sulfite pulp a pulp produced by cooking fibers mainly using magnesium bisulfite or sodium sulfite

—thermomechanical (TMP) pulp a high-yield pulp produced by a process in which wood particles are softened by preheating under pressure prior to a primary pressurized refining stage

—total chlorine-free (TCF) pulp wood pulp that is totally free from chlorine This definition last updated 08/04/2008