1. Steel with oxide skin: manually (electric steel brush) polished to St2 level.
2. Non-scalded steel: manually (electric steel brush) polished to St2 level.
3. Shop primed steel: manually (electric steel brush) polished to St2 level.
4. Welding, cutting or burning damage during fire calibration: after removing welding slag, spatter and polishing, manually (electric steel brush) polish to St2 level.
5. The previous paint film must be completely dry. For the coating that has been cured for a long time, polish the surface and remove grease and dust on the coating surface before painting