Sandtex Trade Rust Inhibiting Primer Undercoat. Prepare your exterior wood and metal surfaces with the superior protection of Sandtex Trade Rust Inhibiting Primer Undercoat. This high-performance flexible solvent-based primer undercoat creates the perfect base for long-lasting Eggshell and Gloss finishes ensuring enhanced adhesion and durability. Key Features Adhesion Promoting Formulation ensures strong adhesion for topcoat finishes enhancing durability. Combined Primer and Undercoat simplifies preparation by providing both primer and undercoat in one product. Ideal for Exterior Wood and Metal a versatile formulation suitable for a variety of exterior surfaces. Coverage and Application Number of Coats Apply 1 coat for effective priming and undercoating. Drying Time Touch dry in 4 to 6 hours ready for recoat in 16 to 24 hours. Application Methods Suitable for application by brush or roller.