This International Standard specifies a method which yields a number that is an estimate of the limiting viscosity number of pulp in a dilute cupri-ethylenediamine (CED) solution. This International Standard is primarily applicable to CED-soluble samples of bleached chemical pulps, but can also be applied to any kind of pulp that dissolves completely in CED solution. NOTE 1 The results can be used to estimate the extent of cellulose degradation caused by cooking or bleaching. Results obtained with samples containing appreciable amounts of substances other than cellulose must be interpreted with caution, however. NOTE 2 In the strictest sense, viscosity measurement procedures are applicable only to the polysaccharide fraction of the sample. This notwithstanding, viscosity measurement can usually be used to obtain a result on unbleached pulps having lignin contents of up to 4 %, because most of these pulps can be successfully dissolved in CED. However, the simple fact that an unbleached pulp can be dissolved in CED does not mean that the results are valid. In summary, viscosity results for pulps containing more than 0,5 % of lignin are not acceptable for technical specification purposes.