Self leveling compound is used to make an uneven floor more level, before installing new flooring. When dried, leveling compound is very hard, very much like cement. Use leveling compound in areas where the dip in the old flooring or subflooring is 1/4 inch or more. Use a trowel to level the compound as much as possible while it is still wet and pliable. Only use small amounts at a time to prevent quick drying before it is level. A grinder can be used to sand down bumps in dried compound. For smaller bumps, a course sandpaper on an electric sander is effective.