Dependable Hood & Ducts Grease Negate powder is a bio-degradable roof and ground cleaner that is used to remove long-standing grease from all types of materials. Grease Negate is best utilized after cleaning a rooftop or wall-mounted fan to avoid it being rapidly washed away during the cleaning. To use, simply remove the seal and use the shaker cap to sprinkle the powder evenly over the desired area. To activate the product and prevent it from blowing away with the wind, be sure to thoroughly wet the area you are treating with hot water before application. Hot water assists in softening the grease and allows the powder to penetrate deeper but is not required for the product to activate. Cold or room temperature water is acceptable.