Double steeping process

SINI Also known as the Double Steeping process. A variation of the viscose process for making regenerated cellulose fibers, in which the treatment with sodium hydroxide is done in two stages, at different concentrations. Invented by H. Sihtola, around 1976. 

Another way to achieve rapid depolymerization is to irradiate the cellulose with a beam of accelerated electrons [146-148]. In this case, the time required for the depolymerization is of the order of seconds. This technology has been investigated as a means to eliminate the need to age alkali cellulose in the viscose process, and rayon has been successfully made from irradiated pulp [149,150]. The process, however, has not been adopted by the industry because, like double steeping, material handling poses special requirements. 

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