New : Surface must be sound, clean, dry and free from all defective or poorly adhering material, dirt, grease or wax. To have better finish, rub down surface using suitable abrasive and dust off before painting
Repainting : better finish, rub down surface using suitable abrasive and dust off before painting. Previously Painted Remove all loose, defective and unstable paint film or powdery residues by thorough brushing and scraping. High pressure water jet is highly recommended. Treat area effected by mould, lichens, algae and moss with any fungicidal wash.