This stuff is boiler slag, which is a recycled product from coal burning plants. When coal is “fired” at over 2500 degrees it melts and produces a by-product called slag. When the slag is cooled through a process called vitrification, it crystallizes, forming sharp, angular granules in a variety of sizes. We reclaim this slag and put it through several screen processes to remove dust and unburnt coal, and then size the remaining crystals into five different “grit” categories.

There are a lot of reasons, but perhaps the one you care most about is because it simply works better. It provides you with the low cost product you want with the high efficiency you need to get the job done quickly.