Abstract: A process for making a refiner mechanical pulp from wood chips which comprises:(a) Comminuting the wood chips largely by splitting along the wood grain;(b) Wetting said particles with a solution of a sulphite salt of an alkali metal to add an amount of said alkali metal salt within the range of 1% to 10% of the oven dry weight of said particles, said solution having a pH within the range of 7 to 12.5;(c) Steam heating the sulphite salt solution bearing particles to a temperature within the range between 80.degree. C. and 165.degree. C. and holding them within that temperature range for a period of 0.5 to 80 minutes;(d) Passing the particles, after said period of heating, through a disc refiner to produce refiner mechanical pulp.

Abstract: A packaging folder formed from a paperboard coated on both surfaces with a coating resistant to water and water vapor, the coating so fractured to be pervious to air but substantially impervious to water. A process by which the coating layers are fractured to give the desired air permeability and water resistance by passing the coated folder around small diameter rollers.