process that gives a viscosity range of about 4 to 5 cps an industry best viscosity variation has a range of about 2 cps as indicated previously the existing i e conventional pulp irradiation process is an off line treatment the starting dp is accurately known and based on the irradiation equipment and the final required viscosity dose an optimum number of pulp sheets for a minimum cost process can be determined in this example with various tests and with particular reference to fig6 the optimum number of sheets indicated by the equipment supplier was 12 pulp sheets when irradiated at the prescribed dose of 15 kgray the results were as shown in fig6 the viscosity variability obtained was about 1 2 cps on average the invention therefore provides a method of reducing off spec material as against the conventional chemical route by using the process to trim or adjust the dp post the h stage or to apply higher dose of radiation post the dp 2 stage and thereby save on hypochlorite this results in a chemicals saving and an environmental pollution abatement or improvement the invention also provides an improvement of the product quality in terns of a reduced dp range variability at the normal 14 to 20 cps standard viscose supply range this.