Hot dip (or hot) galvanizing is the processing technique to dip the pretreated base substance of carbon steel into melted liquefied zinc to obtain a protective zinc coat. Due to its good anticorrosion performance, galvanized plate is vastly applied into the industries of home appliance, decoration, advertisement, and civil construction, etc. Particularly, the home appliance industry (outer shell of air conditioner, outer plate of refrigerator, outer shells of washing machine, computer, and microwave oven, etc.) has large demands on galvanized and color coated plates.