Calcium oxide when heated with silica sand and sodium carbonate, forms a peculiar solution. When this solution cools down, it forms an amorphous, clear, colorless solid called glass. The quicklime is contacted with an aqueous solution of a boron-containing compound after being calcined. The boron-containing solution can be sprayed on the quicklime as it moves past on a conveyor belt. The retarded quicklime can be used for various industrial purposes and is especially useful as a reactant in a glass making operation.