Why would a bolt be zinc plated?

A bolt is zinc plated primarily to enhance corrosion resistance. Zinc plating serves as a protective barrier between the underlying metal, usually steel, and the environment. This is essential because steel is prone to rust and deterioration when exposed to moisture and air. The zinc layer acts sacrificially; it will corrode in place of the steel, thus prolonging the life of the bolt. This protective property is vital in applications where bolts are exposed to harsh conditions, such as outdoor use or in environments with high humidity.

While enhancing aesthetic appeal may occur as a side effect of zinc plating, its primary purpose is not aesthetic enhancement, but rather to protect the material. Improving strength and reducing weight are also not relevant to zinc plating; these factors are influenced by the material composition and design of the bolt itself, not the plating process.