Mohit Nigam, B. Agarwal, B. Yadav, Dhannajay Kumar, Manufacturing of Paper by Sulphate (Kraft) Process, in International Journal of Scientific Research and Reviews, vol. 3, n. 1, Marzo 2014, pp. 106-120, ISSN 2279-0543 (WC · ACNP).
«Kraft pulping involves treating wood chips and sawdust with a sodium sulphite and sodium hydroxide solution. The highly alkaline chemical and wood mixture is cooked with steam under pressure (digested) for between 1 and 3 hours»