Plumbago is very resistant to high and low temperatures hence its use with higher melting point metals such as iron and will prevent silica pick up on the casting. High temperatures can fuse silica to the surface in a vitriolic layer. Plumbago can be applied as a parting powder to prevent sand sticking to patterns and sand sticking to sand. It can also be dusted onto the mold after formation, or can be mixed with carriers such as water and isopropanel alcohol and sprayed on and the alcohol burnt off or torch dried to evaporate moisture. It can also be applied by brush or swab on baked or sodium silicate cores and moulds.
Plumbago also has excellent lubrication qualities and moulding box alignment pins should be coated with it. Oil should not under any circumstances be used as it will pick up sand and cause wear to the pins.