Spectrum 500-Series Underglazes are all lead-free, dinnerware safe, and A/P non-toxic when covered with a clear glaze. These underglazes can be applied to bisque or raw clay. Two to three coats are required for opaque, vibrant colors. The sample shown is at cone 05, but these underglazes can be fired from cone 06 to cone 10. Some color variation will occur at higher temperatures. Other variables such as clear glaze, thickness, and clay body can also affect the hue of each underglaze. Testing is recommended.