So with the primer down and dry (no more than 24 hours ideally) and a little dam built of 1/4″ weatherstripping to hold back the tide, It was time to pour underlayment. This powdered substance is made by a variety of companies but the gal at Home Depot told me the Custom brand LevelQuikRS is the best. So I mixed it up per the directions for two+ minutes until I had a smooth but pourable consistency – about that of pancake batter. Using a notched trowel I smoothed it into my confined test site, skiming it evenly towards edges and corners. It worked great and 4 hours later I had a rock hard, smooth finish.