Zinsser OKON W-1 Water-Repellant Sealer with micro-Plug™ technology penetrates deeply to effectively plug surface pores, preventing water absorption. Paintable, recoatable and ready to use. For use on vertical surfaces—cast concrete, tilt-up panels, unglazed brick, etc. Prevents efflorescence, freeze-thaw damage, dusting and staining; breathable. Clear, non-yellowing; water-based, low VOCs and very low odor. For best results apply using a low-pressure airless spray pump.