It is important to realize that the sand in a bunker is not at a consistent depth throughout the entire bunker area. Sand on the sloped face normally is kept shallow to help avoid plugging or fried-egg lies. The depth gradually increases to the flat portion of the hazard. Generally, the base or floor of a greenside bunker needs 4 to 6 inches of sand, whereas a fairway bunker commonly needs 2 to 4 inches. That said, the exact depth should be determined by the physical attributes of the sand and desired playability. Laboratory testing can eliminate much of the guesswork. An accredited physical analysis laboratory measures particle size distribution and particle shape, the ability to retain moisture and saturated hydraulic conductivity (water movement). The lab can even run specialized tests to predict the likelihood of fried-egg lies. These tests are helpful in selecting an appropriate sand that plays well for the golfer and is easier to maintain for the golf course superintendent.