After a short preheating of the chips in steam in the interval 115–155 °C the
chips are refined in a pressurised system. Refiner pulp, which is produced without preheating, is
called refiner mechanical pulp (RMP). Chemi-thermomechanical pulp (CTMP) is a special type
of TMP. In CTMP processes the chips are initially impregnated with small amounts of lignin
softening chemicals, and then heated with steam to approximately the same temperature interval
as in the TMP process.