The great thing about hard wood floor surfaces such as ceramic or natural stone is that they are beautiful, durable and long lasting. While many of them are processed in a way that leaves them virtually impenetrable, such as glazed ceramic tile like you would find in a bathroom shower, most are not. This leaves them fairly porous and open for penetration from dirt, grime and grease. In addition, grout, which is usually cement-based, is extremely porous.