Binders, Cores, Silica Sand, Casting, Core Testing - Scientific .sodium silicate, sodium polyphosphate and silica sand for the production of . kg/cm2, scratch hardness number of 85 and also sublime surface finish for the.scratch hardness for silica sand,Mohs Scale of Hardness - Mineralogical Society of AmericaOrthoclase, 6, Orthoclase (white) on quartz, Baveno, Italy Orthoclase crystal is 3 cm tall. Seaman . The effects of high hardness are important in many fields.
scratch hardness for silica sand