key block (woodblock printing)
Technical term in traditional Japanese woodblock printing (ukiyo-e). The key block carries the main outlines and is printed first, usually in black.
浮世絵では、まず主版を彫り、それから色版を作る。
In ukiyo-e, the key block is carved first, and then the color blocks are made.
From おも, “principal or main,” and 版, “printing block.” It denotes the key block that supplies the principal outlines in multicolour woodblock printing.