Surfactant stabilized latex, developed for use as a waterborne stain-locking primer vehicle. A stain-locking system means that the primer coat picks up any solubilized stain from the substrate, locks and traps it, preventing the stain from migrating into the topcoat. Designed for use over wood and walls. Uses a specific chemistry, which gives stain-locking capability without needing to formulate with reactive pigments such as zinc oxide (ZnO).