Surfaces must be sound, clean, dry and free from all defective or poorly adhering material, dirt, grease or wax. Remove all loose or defective paint or powdery residues by thorough brushing and scraping, using a stiff fiber brush and high pressure water jet. Treat any areas affected mould, lichens, algae and moss with Dulux Fungicidal Wash. Make good minor defects with a suitable exterior grade Filler. Surfaces that remain powdery, friable or chalky after thorough preparation should be sealed with one coat of an appropriate Primer (see below). It should not be applied on areas where moisture reading (as measured by Protimeter) exceeds 17%. These wall should be left to dry further. Note: Do not apply Dulux Weathershield Powerflexx during wet weather.