"木材着色剂" can be translated into English as "wood stain" or "wood coloring agent".
"Wood stain" is a more commonly used and specific term in the industry, referring to a type of pigment or dye applied to wood to change its color or enhance its natural grain.
"Wood coloring agent" is a more literal translation that also accurately conveys the meaning, though it may be slightly less common in everyday usage.
In most contexts, especially in carpentry, woodworking, and home improvement, "wood stain" would be the preferred choice.