But there's more to blackening than just exposing the pottery to black smoke. The clay itself must be high in iron oxide for the smoke to penetrate. After trying many different types, Li finally settled on red clay from a couple of different places (Chingshui Rural Township in the Tatu Mountains, and Yuchih Rural Township in Nantou County).
此外，陶體要黑，除靠煙薰外，陶土本身需含大量氧化鐵，才能相輔相成，最後李幸龍選用「清水大度山脈紅土」和「南投魚池鄉紅土」。