Dulux Trade Weathershield Preservative Primer (BP) penetrates into wood to seal and preserve against water damage, decay and blue stain fungi. Provides 8 year weathering durability, when used as part of the full Weathershield exterior paint system. Offers 8 year all weather protection and penetrates & seals new bare wood. Protects from decay and blue stain fungi. Water based. Apply this primer from the Dulux Trade range to exterior surfaces using a brush to prepare the surface for painting. It takes 24 hours to dry and will cover up to 4-5m² per litre on average. This primer has a preservative formula that protects and seals new bare wood, protecting it from water damage, decay and fungus. This comes with 8-year all-weather protection that makes this the ideal solution for exterior wood surfaces, such as sheds and decking. This primer gets a modest coverage of 4.5m² per litre.