About RainCoat® Clear Water Repellent (Water Base) Protect exterior wood from prolonged exposure to water and sun with Rust-Oleum® Wolman™ RainCoat® Clear Water Repellent (Water Base). This fast-drying formula provides one-coat coverage and will adhere directly to damp wood—so you can clean and coat in one day. 100% clear, matte finish reveals original wood color and allows wood to gray naturally. Long term water repellency exceeds Federal specifications. Protects against cracking, splitting, warping. Mildew-resistant coating film keeps wood free of mildew stain.