Does sealer make marble more porous over time?

Q. My friend cleans houses for a living, she mentioned she has seen marble showers become porous with time. Is this due to having a sealant?

A. Marble is a porous stone. Sealers can enhance stain resistance by filling the pores of the stone and inhibiting stain-causing substances from penetrating into the stone. If a marble shower had been previously sealed, that sealer will wear off over time, and the tiny pores in the stone will be exposed once again. While sealers do not actually prevent stains, they can allow marble owners the time to clean away stain-causing substances before they turn into stains. A PRO may or may not recommend sealing marble to enhance its stain resistance, because not all stone needs to be sealed. Highly polished stone may not even take an impregnating sealer. Sealer selection and application is a job for a professional stone restoration contractor. To learn more about sealing and other marble services a PRO can offer, visit https://surphaces.com/marble/.