... air permeability, it is a new type casting material for precision casting, coated sand and self hardening sand etc ... Precoated sand;, Sodium silicon sand , Resin sand, Precision casting etc. Advantages:Spherical grain, low thermal expansion, good ... Application:Waterglass bonded sand, resin bonded sand, precision casting, Expendable Pattern Casting (EPC), Copper and Aluminium articles polishingChemical: ...