To undergo prolonged and thorough tempering or refinement; to be severely tested and purified over a long period.
这位匠人制作的陶器，每一件都经过九蒸三熯的工序，方能呈现出温润如玉的光泽。
Each piece of pottery crafted by this artisan undergoes a process of prolonged and thorough tempering, only then revealing a jade-like luster.
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