PPGI steel is short for pre-painted galvanized iron, which refers to pre-painted zinc-coated steel. As the name implies, PPGI commonly uses a hot-dip zinc-coated steel (GI) as a substrate. Then the GI sheet in coil form is cleaned, pre-treated, and painted with layers of organic coatings, such as PE, SMP, HDP, PVDF, etc. The painting process is continuous, which is known as coil coating process. That’s why PPGI steel consists of several layers, namely base metal, zinc coating, pre-treatment (chemical conversion coating), primer coating, and top/back coating. Below is a structure drawing for you.