BODY by the reaction of common salt with the clay body constituents, particularly silica, toward the END of the firing.Glaze can be formed on stoneware by throwing common salt into the kiln at the peak TEMPERATURE of around 1000 - 1300 o C.Sodium from the salt combines with silica in the clay to FORM a glassy coating of Sodium Silicate. COLOUR of the glazeConstituentOrangeSodium SilicateShades of brownIron OxideBlueCobalt OxidePurpleManganese Oxide