Granite and marble are porous materials and are subject to staining if not taken care of properly. In granite, the same porosity that allows for staining also allows for easy stain removal. In most cases, stains can be prevented by quickly blotting the spill with a paper towel. Don't wipe, as this will spread the spill. If a spill is left overnight, especially if the liquid is grease, oil, coffee, or wine the granite will usually darken. To remove the stain, a poultice should be used, which may pull out the stain from the granite. Marble can be stained and etched by acidic or oil-based products.