All natural stone is porous because of the sheer number of capillary pores that liquids and gases can move around. There are many types of natural stone, such as; sandstone, limestone, marble, travertine, slate, granite and basalt; all have porous materials that act like hard sponges, and soak up liquids, dissolved salts and minerals over a long period of time. Sandstone is considered a very porous stone as it absorbs liquids fairly quickly, whilst the more dense igneous stones like granite are much less porous and can take an hour or more to absorb water-based liquids and oils. impregnaty akemi