ProSlide® Engineered Infield Topdressings from DuraEdge Expanded Shale will absorb a very small amount of water, allowing it to drain through to be absorbed by the infield soil where you need moisture. Calcined Clay will absorb large amounts of water. Many groundskeepers have found you’ll get the best result from blending the two types together. A ratio of 60-70% expanded shale to 30-40% calcined clay is a good place to start, adjusting from there to get the performance you want.