Thompson's WaterSeal Advanced Maximum Strength One-Coat Waterproofer - Specially formulated for wood, Thompson's WaterSeal Advanced Maximum Strength One-Coat Waterproofer provides one-coat maximum strength protection with a coating that resists mildew and UV damage, allowing your wood to maintain its natural color. With a patented formula, this advanced waterproofer enables you to clean and treat in one day and to apply immediately to new pressure-treated wood.