Black engraving: When laser engraving metals such as tombac or stainless steel, the interaction of the melted base material with the oxygen in the air causes oxides to form, which settle in color. The resulting surface is rather rough and thus absorbs a lot of light. The engraving appears black. On stainless steel, the engraving may also appear dark gray. On items with a high brass content, the engraving may appear black to dark brown.
White engraving: With white engraving, the surface is only slightly melted. The result is a smooth, highly reflective surface - on stainless steel, the engraving looks white.