Why does galvanizing coating look different?
You may noticed, some products after hot dip galvanization (HDG) coating, even in the same facility using the same process may look different from others. It can be noticeable that some of the product will be much brighter and other much darker.
There is nothing wrong with the product nor with the coating and any difference will depend on the product steel.
Coating thickness and content of silicon in steel may cause different appearance on the finished product.
Please refer to this article for more details: The HDG Coating (galvanizeit.org)