15 Pounds - Calcium Carbonate - Limestone Powder - Rock Dust - Great Soil Amendment and Fertilizer 4 Ounces of Calcium Carbonate Used in 100s of Industries for Multiple Situations Increases Minerals in Soil Odor & Moisture Absorpent If using as chalk paint powder you should not expect a completely smooth surface without any sanding. As you can see in the photo, there is a slight grittiness to it.