Do You Know How Glass Insulators Composite & Porcelain Insulators are Manufactured? Nooa Elecrtic Will Tell You: Glass insulators are made by melting raw materials like lime and quartz at high temperatures,then rapidly cooling them in a mold,Composite insulators consist of a core rod,housing,and end fittings,often using fiberglass-reinforced polymer (FRP) and silicone rubber,Porcelain insulators are produced by mixing raw materials like quartz,feldspar,and clay into a slurry,shaping it,drying it,and then firing it in a kiln,