This chakai is not a utensil in which to reduce the temperature, but into which to pour the tea temporarily which was brewed in appropriate concentration from a kyusu (small teapot called 'chatsubo').
この茶海は湯温を下げる道具ではなく、適度な濃度に抽出された茶を急須（「茶壺」という）から一端移しておく道具である。