Travertine countertops should be cleaned with a neutral pH cleaner, as acidic or abrasive cleaners may damage the stone. In the case of stains, a poultice made from a mixture of baking soda and water or hydrogen peroxide can be applied to the affected area and left to sit for several hours before being rinsed off. For particularly stubborn stains, a commercial stone stain remover specifically designed for use on Travertine may also be effective, but it is important to carefully follow the manufacturers instructions and test the product on a small, inconspicuous area first.