Density is an important parameter of silica sol. Its size is positively correlated with the content of silica particles. Therefore, the silica content of silica sol can be indirectly judged from the density (specific gravity) of silica sol. In addition, when silica sol has a tendency to gel, the density of silica sol will also change. In actual production applications, if the density of silica sol in the coating separated by a centrifuge changes, it should be paid enough attention. The conventional method for measuring the density of silica sol is to follow the density meter determination method in JB/T4007-1999 Investment Casting Coating Test Method.