The low-fire Cone 06 Metallic glazes are lead-free, but are NOT dinnerware safe due to the use of heavy metals such as copper and manganese. These glazes work best at Cone 05 with a generous 3 to 4 coat application – the thicker the better. 151, 152, and 153 fire out glossy whereas 154, 155, and 156 have a more matte finish.