British Paints PREP 4in1 Water Based is a multi-purpose water-based preparation coat, suitable for use on interior and exterior surfaces. British Paints PREP 4in1 Water Based combines the functions of sealer, primer, undercoat and stain-blocker in one convenient product. British Paints PREP 4in1 Water Based has great hiding, filling and adhesion properties, making it ideal for covering oil-based stains and food and beverage stains.