This part of GB/T 19421 specifies the method for the determination of whiteness in layered crystalline sodium disilicate. This section applies to the determination of the whiteness of layered crystalline sodium disilicate that can be used as a detergent builder.
GB/T 19421.2-2003 history
2008GB/T 19421-2008 Test methods of crystalline layered sodium disilicate
2003GB/T 19421.2-2003 Test methods of crystalline layered sodium disilicate--Measurement of whiteness