Pre-coated primer, also known as shop primer, is a temporary protective primer. Shop primer provides temporary protection for up to 12 months. Its main function is to provide rust protection during the interval between processes after sandblasting and rust removal of steel, preventing the steel from rusting during processing and storage.
Key characteristics include a generally thin film thickness (e.g., 10-15µm), good weldability and cutting performance, and a small burn-off area. For shop primers with high zinc powder content (e.g., epoxy zinc-rich shop primer), if the film thickness exceeds 20µm, a large amount of zinc oxide fumes will be generated during cutting and welding, which is detrimental to the health of workers. Common varieties include inorganic zinc silicate shop primer and epoxy zinc-rich shop primer [7] [14]. Inorganic zinc silicate primer has cathodic protection, dries quickly, has excellent heat resistance (can withstand high temperatures of 400℃), excellent welding and cutting performance, and a small burn-off area.
