Dark Oak Sign is the dark-wood variant of the Minecraft sign, a non-solid block with no collision (mobs and items move straight through) that displays up to four lines of text on each side. Dark Oak Signs never generate naturally: oak signs appear in igloo basements and spruce signs in taiga village houses, so the only source is the crafting table, where 6 Dark Oak Planks over 1 Stick produce 3 signs. The recipe accepts a single plank type, so a mixed-wood grid yields no dark oak signs. An axe breaks a Dark Oak Sign fastest, any tool or an empty hand also works, and a sign drops as an item whenever the support block is moved or destroyed. Dark Oak Signs stack to 16, never catch fire, and can be waterlogged (water occupies the same block space without breaking the sign).

Players rely on Dark Oak Signs to label storage rooms, mark paths, and leave notes that match other dark oak blocks. A dye recolors all four lines of a sign's face, a Glow Ink Sac makes the text glow, a regular Ink Sac cancels the glow, and a Honeycomb waxes the Dark Oak Sign so the text cannot be edited. Water and lava flow around Dark Oak Signs and destroy nothing, so a single sign can control the flow of a fluid stream. One Dark Oak Sign also smelts exactly one item as furnace fuel. Placed on top of a block, a Dark Oak Sign stands on a short post and faces the placer in one of 16 directions, keeping labels aligned with shelves and doorways.