How to distinguish between cold-dip galvanized and hot-dip galvanized wire mesh fences?

Galvanizing is widely used in the fence industry, and this process is divided into hot-dip galvanizing and cold galvanizing. What are the differences between these two galvanizing processes? Let's take a look.

Differences between Hot-Dip Galvanizing and Cold Galvanizing

Hot-dip galvanizing involves immersing the object in molten zinc. The galvanizing process uses a single current to gradually coat the metal surface in an electroplating tank. Hot-dip galvanizing is faster, produces a thicker zinc layer, but consumes more zinc. Regular galvanizing is slower and produces a thinner zinc layer.

Cold galvanizing refers to electroplating, while hot-dip galvanizing involves immersing the object in molten zinc. The difference between hot-dip galvanizing and cold-dip galvanizing is that the former has poor corrosion resistance, while the latter has good corrosion resistance. Hot-dip galvanizing can maintain its corrosion resistance for more than ten years in outdoor environments, and this process is generally used for steel structures with small components.

Now that we know the difference between hot-dip galvanizing and cold-dip galvanizing, let's look at what hot-dip galvanizing and cold-dip galvanizing actually are.

What is hot-dip galvanizing?

Hot-dip galvanizing, also known as hot-dip zinc plating, involves melting zinc ingots at high temperatures, adding some auxiliary materials, and then immersing the metal structural components in a galvanizing bath, causing a zinc coating to adhere to the metal components. Zinc's advantages lie in its strong corrosion resistance, high adhesion, and high hardness of the galvanized layer. Disadvantages include its high price, the need for significant investment in equipment and space, the difficulty of fitting large steel structural components into the galvanizing bath, and the fragility of steel components, making them prone to deformation under heat. The commonly referred to "zinc-rich coating" generally refers to anti-corrosion coatings containing zinc powder.

What is cold galvanizing?

Cold galvanizing is essentially electro-galvanizing. The cold galvanizing process protects metal from corrosion by using a zinc-filled coating. This coating is applied to the surface of the object being protected using any coating method, and after drying, forms a zinc-filled layer with a zinc content of up to 90%. It is suitable for repair work (i.e., during repair work, only damaged areas of the protected steel surface need to be repaired before recoating). Cold galvanizing is used for corrosion protection of various fence products and structures. This process involves a very low zinc coating amount, only 10-50g/m², and its corrosion resistance is significantly lower than that of hot-dip galvanizing. Therefore, electro-galvanizing is relatively cheaper.