Hot dip galvanizing and cold dip galvanizing are both processes of zinc processing. Hot dip galvanizing involves melting zinc, while cold dip galvanizing uses electrolysis. They have significant differences in production, but their finished product performance is similar. So, how can we distinguish them.
The difference between hot-dip galvanizing and cold dip galvanizing
1. Different thicknesses
The zinc layer of hot-dip galvanizing itself is relatively thick, generally with a thickness of more than 10um, so it has good anti-corrosion ability. Although the surface is bright, it is slightly rough and may even have zinc flowers. The zinc layer of electroplated zinc is very thin, only about 3-5um thick. Although the surface is smooth, it may have a dull and dirty appearance, with good processing performance but insufficient corrosion resistance.
2. Different production volumes
Hot dip galvanizing belongs to mass production, so it has a good output. However, galvanizing cannot be produced in large quantities, so its output is relatively low.
3. Different prices
The surface effect, processing performance, and bonding strength of electroplated zinc are all inferior, and the price will be higher than hot-dip galvanizing. Moreover, the cost of electroplated zinc itself is higher, so its price is also higher.
4. Different coating structures
The surface of hot-dip galvanizing belongs to pure zinc coating, which is uniform and pore free. However, there is still a layer of brittle compound between the coating and the substrate. The coating of electroplated zinc is only composed of zinc atoms, which are deposited and precipitated on the surface of the steel strip. It belongs to physical adhesion and has many pores on the surface, making it more susceptible to corrosion.
They can be distinguished from several aspects
1. Distinguish from the process
There are many processing techniques for hot-dip galvanizing, which require the workpiece to be degreased, acid washed, impregnated, and dried before being immersed in a molten zinc pool. After a certain period of immersion, it can be extracted, which is the process of hot-dip galvanizing. Some hot-dip galvanized pipe fittings are processed in this way. Cold galvanizing is actually electroplating, which is processed using electrolytic equipment. After undergoing processes such as oil removal and acid washing, it is immersed in a solution containing zinc salts, connected to the electrolytic equipment, and deposited with a zinc layer on the workpiece during the directional movement of the positive and negative electrodes.  
2. Distinguish from appearance
The overall appearance of hot-dip galvanizing is slightly rougher, with the appearance of process water lines, droplets, and other marks, especially on one end of the workpiece, which is clearly silver white overall. The surface of electroplated zinc is relatively smooth, mainly yellow green, but there are also colors such as rainbow, blue white, and white with green light. The entire workpiece basically does not have zinc nodules, clumps, or other phenomena.
