Like all unsealed natural materials, cement tile has inherent pores in the surface which left unsealed will allow staining to occur. When Geon Tile is sealed with NanoSeal GT, you should expect years of use before a new coat of sealer will be recommended. For more detail or maintenance of Geon Tile, please refer to the care and maintenance guideline here https://mk0geontilev5ky0x10i.kinstacdn.com/wp-content/uploads/2019/11/GT10011.09.19-NanoSeal-GT-Product-Sheet.pdf