The thickness of the zinc coating is directly related to its durability. A thicker coating generally provides better corrosion protection because it takes longer for corrosive agents to penetrate through to the aluminium substrate. However, as mentioned earlier, there are limitations to how thick the coating can be.

　　The required coating thickness depends on the application and the expected service life of the product. For applications in mild environments, a thinner coating may be sufficient. For example, in indoor applications where the product is not exposed to harsh conditions, a coating thickness of a few micrometers may be adequate. However, for outdoor applications or in corrosive environments, a thicker coating of 10 - 50 micrometers or more may be necessary.

　　It's important to note that the coating thickness should be uniform across the entire surface of the aluminium substrate. Uneven coating thickness can create weak spots where corrosion is more likely to occur. Therefore, during the plating process, steps must be taken to ensure a consistent coating thickness, such as proper agitation of the plating bath and uniform distribution of the current.