鋳造法
鋳造とは、鉄、アルミニウム合金、青銅、銅、真鍮などの金属を融点以上に加熱し、できた液体を型に流し込み、冷却して製造する方法です。
大仏の場合、木製または塑土の模型像が用意され、塑土の外型が作られます。次に、外型と一致する2番目の中型が作成されます。金属面の望ましい厚さを計算し、その厚さに合うように中型を調整します。中型と外型を所定の位置にセットし、それぞれの周りに土を積み上げて支えます。その後、溶融した金属を外型と中型の間の空間に注ぎ込み、冷却します。このプロセスは、下から上に徐々に積み上げられる段の継ぎ目に対して繰り返されます。像の特定のセクションに応じて、継ぎ目の接合部を強化するために、さまざまな高度な技術が用いられます。外型と中型は、さまざまな継ぎ目が結合されるにつれて徐々に構築される大きな盛土によって支えられます。大仏の場合、身部だけで7段階の鋳造作業が必要でした。全体のプロセスが完了すると、外型とそれを支えていた盛土が取り除かれました。それから、中型とそれを支える中土は、大仏像の背面の窓から取り除かれます。
Bronze Casting of the Great Buddha
Casting is a process in which metals such as iron, aluminum alloy, bronze, copper, or brass are heated to beyond their melting point and then poured into a form, allowed to cool, and thus set into the desired shape.
In the case of the Great Buddha of Kamakura, a wooden or clay model was prepared, and an outer shell of clay was made. A second, inner clay shell was then made, matching the outer shell in shape, with the gap between the two equal to the desired thickness of the metal casting. The inner and outer shells were set in place and earth was piled up around each of them to provide support. Molten metal was then poured into the space between the outer and inner shells and allowed to cool. This process was repeated for each succeeding segment of the image, which was built up from bottom to top. Advanced techniques were used to strengthen the junctures of the segments. The outer and inner shells were supported by great mounds of earth gradually built up as the various segments were cast and joined. In the case of the Great Buddha, the body alone required seven different casting operations. When the entire process was completed, the outer clay shell and the earth mound that supported it were removed. Then the inner shell and the earth that supported it were removed through the window that is still visible on the back of the statue.
