Lead of mechanical pencils
About the color Spare Leads
There are two kinds of color Spare Leads . The same as colored pencils, a non-calcined core made by extrusion molding of pigments, waxes and resins, and boron, talc, mica, and clay minerals are formed and heat treated at 600 to 1000 °c in an oxygen atmosphere to make a white core, and a baked core impregnated with each color ink in a white core. The non-firing core has a soft writing taste but no strength. The firing core has a high strength, but because it is porous in order to impregnate the ink, it becomes weaker compared with the black core.
