The galvanization on the galvanized steel coil surfaces makes the steel have a great corrosion resistance. Then the service life is very long. Therefore, it is widely used into many industries. But during the galvanized steel coil production process, it maybe come accross many problems because the production process is not rigorous.
Black spot is one of the problems. From the years of production experience, CAMELSTEEL finds that the black spot will affect its subsequent processing of surface quality. If it is very serious, the steel will scrap. So people need to give the tips according to the causes.
1. When people do the spray, the outfall is not seal up well, some organic thing mingled with the spray will cause the black spot on the surface.
2. On the chemical cause, the zinc produced in the zinc layer will produce hydrate, and the exposure parts will have chemical reaction and the color is black.
3. The passivation liquid is swing on the board.
4. The place, where the black spot in on, is not protected carefully. And it is damaged by extruded and friction.