Stealthy dark finish on steel; wears into a cool two-tone.
What it is
Black oxide is a chemical conversion finish, most common on steel. Instead of adding a thick coating, it converts the outer surface into a very thin layer of black iron oxide, so it barely changes the part's dimensions. It is usually sealed with oil or wax afterward. The exact process and look, from deep black to charcoal gray, depend on the maker.
How it feels in your EDC
Black oxide gives a classic, low-sheen dark look with a tool-like, utilitarian feel. Because it is so thin, it keeps the crisp edges and texture of the machined surface underneath. It is generally less wear-resistant than coatings like DLC, PVD or Cerakote, which build a separate layer on top of the metal.
Care & aging
With daily carry, high spots and edges gradually wear back to bright metal, creating a natural, worn-in contrast that many people enjoy. Black oxide offers only mild corrosion protection, so keep it dry and wipe it with a lightly oiled cloth now and then, keeping oil away from bearings and magnets unless the maker recommends it. Avoid abrasive polishes.
是什么
发黑（Black oxide）是一种化学转化处理，最常用于钢材。它不是额外加一层厚涂层，而是把外表面转化成一层极薄的黑色氧化铁，因此几乎不改变零件尺寸。处理后通常用油或蜡封闭。具体工艺和外观（从深黑到炭灰）取决于品牌。
上手感受
发黑呈现经典、低光泽的深色外观，带有工具般的实用感。由于非常薄，它能保留底下加工面的锐利边缘和纹理。它的耐磨性一般不如 DLC、PVD 或 Cerakote 等在金属上另加一层的涂层。
保养与老化
日常携带后，凸起处和边缘会逐渐磨回亮金属，形成很多人喜欢的自然使用对比。发黑只有轻度防锈作用，要保持干燥，偶尔用略带油的布擦拭；除非品牌建议，否则不要让油接触轴承和磁铁。避免研磨抛光剂。
