1.1 The sodium silicates in general use in the paper industry consist of chemical combinations of SiO2 and Na2O in ratios varying from about 1:1 to about 4:1.
1.2 They are available as aqueous solutions, anhydrous solids, and crystalline hydrates depending upon their chemical composition and the use for which they are intended. These uses will influence the tests which are required. When the utility is based on their chemical nature, the essential determinations are the Na2O and SiO2 content; when used as an adhesive, their viscosity and specific gravity become important.