What sand is used for water glass casting in lost wax pattern? How to arrange the shell-making process?

depending on what kind of casting material you make, the surface layer of carbon steel is generally quartz sand powder, and the back layer is mostly made of quartz powder and refractory powder to prepare coatings and sprinkle quartz sand. But I think mullite sand powder is easy to use and control. Corundum or mullite powder is used for alloy steel or stainless steel surface layer, and Moraine sand or corundum sand is used for sanding. The hardener is generally ammonium chloride, crystalline aluminum chloride, polyaluminum chloride, etc. . . Hierarchical arrangement can be determined according to the size of the parts and customer requirements.