Unglazed tiles should be sealed with liquid tile sealant during the installation process, even if you want them to retain their flat look (sealants come in gloss and non-gloss finishes, just like paint). ... Cut the tiles at the edges of the floor as needed on your tile cutter. Let them set overnight.

Can unglazed ceramic tile be sealed?

With unglazed ceramic tiles, any quality penetrating surface sealer will work to seal both the tile and the grout. When both the tile and grout are being sealed at the same time, the sealer can be applied with a mop.

How do you seal unsealed tiles?

A common technique for applying sealant is using the wipe-on / wipe-off method. Evenly coat a sponge with sealant and then apply liberally to the tile area. Let the sealant dry for at least 20 minutes then rub the excess off with a clean, slightly damp sponge. Continue the process at least four times.