stone sealing is the application of a surface treatment to products constructed of natural stone to retard staining and corrosion. all bulk natural stone is riddled with interconnected capillary channels that permit penetration by liquids and gases. this is true for igneous rock types such as granite and basalt, metamorphic rocks such as marble and slate, and sedimentary rocks such as limestone, travertine, and sandstone. these porous channels act like a sponge, and capillary action draws in liquids over time, along with any dissolved salts and other solutes. very porous stone, such as sandstone absorb liquids relatively quickly, while denser igneous stones such as granite are significantly less porous; they absorb smaller volumes, and more slowly, especially when absorbing viscous liquids.