When quarried, Indiana Limestone contains ground water. This is commonly known as quarry sap. Normally buff stone does not require seasoning beyond the usual sixty to ninety days quarrying, sawing and fabrication process. For best immediate color uniformity, gray stone should be seasoned a minimum of six months prior to setting in the wall. This allows the organic matter in solution to stabilize. The organic matter will oxidize upon exposure to the elements causing gray stone to lighten in color with age. Due to the seasonal nature of the quarry operations in Indiana, it is sometimes necessary to use unseasoned stone. This is an approved practice in the industry; any resulting discoloration will disappear, usually within a few months after the stone is set. To mitigate the potential for staining, the use of gray stone in interior applications should be limited to fully seasoned material. Although ILI and its member companies urge contractors not to use the limestone shipper’s celotex or similar pads as separators for long-term storage, this practice occurs. It can result in comparatively long-lasting figuring of the stone, especially in the case of stone containing quarry sap. Although most of these “pad marks” will ultimately go away by themselves, and can usually be removed with special efforts, stubborn marks occasionally remain. It is much easier to avoid this problem by using non-absorptive spacers which allow air to circulate. ILI or its member companies will be happy to comment to inquirers on the subject. (See Contractors Handbook on Indiana Limestone, p. 1.) natural bed Indiana Limestone is a sedimentary formati