The FZ/T 50010.7-1998 standard specifies a method for measuring the whiteness of pulps for viscose fibers, using the blue light diffuse reflection factor determination method. This method evaluates the whiteness of pulp samples by measuring their diffuse reflection factor under blue light at a wavelength of 457 nm. The standard describes in detail the Geometry conditions and Light spectrum characteristics of the instrument, including the use of an analog D65 Light source and appropriate Light spectrum filters. During the test, the samples are placed evenly according to the specified thickness to ensure that changes in their thickness do not affect the whiteness measurement results. The final result is expressed in terms of the blue light diffuse reflection factor of the sample, and detailed sample information and test results are required to be included in the report.