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.
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.