Whether you’re working to get stains out of an old, neglected marble mantlepiece, or rust stains out of a newer marble shower, the method remains the same. Marble is a porous material — as is our skin, and like our skin when we have a wound, making a poultice to draw the stain out of your marble works in just the same way making a poultice to draw out infection in a wound would. The recipe may vary depending on the stain, but the poultice method is consistent.