If you have porcelain tiles in your home and there seems to be a film or residue on them, this can be caused by a few things, all of which are removable.
Porcelain Tile Overview
Porcelain tile is a man-made tile product made primarily of clay or clay dust. The product is produced under tremendous pressure and fired to high temperatures. The result is a tile that is nonporous, with an extremely low water absorption rate. What this means is that the tile will not absorb any substance, and any residue or film on the tile remains on the surface, making it easier to clean up.
Grout Haze
If your porcelain tiles have just been grouted, and they appear cloudy or covered in a film, this could be due to grout haze. Grout haze is left-behind particles of cement that were not fully removed from the surface of the tile during clean up. If the grout haze has only been on for a short time, it can be cleaned off with a dry paper towel.
If the grout haze has hardened onto the tile, dissolve 1 cup of sugar into 1 gallon of warm water. Pour it on the tiles and allow it to soak into the haze for a few hours. Clean the tiles up with a standard tile cleaner.
Sealer Residue
While most porcelain tiles require no sealing, polished porcelain tiles should be sealed prior to grouting to help facilitate easy grout cleanup. Your grout joints may also have been sealed, resulting in excess sealer getting on the tiles. If too much sealer has gotten on the tiles, it can leave a film.
If the sealer is fresh, you can apply more sealer to it to emulsify the old sealant, cleaning up both layers at once. If the sealer is more than a few weeks old, purchase a sealant stripper to remove it.
Tile Saw Residue
If your tiles have just been installed, and you have a pattern that required multiple cuts, you may have tile saw residue on the tiles. Tile saws use water to cool the blade as they cut. This water can mix with the tile dust to produce a slurry that can get on the face of your tiles, drying there. This can appear as a chalky, white film. To remove it, simply wash the tiles with any tile cleaner and rinse well with clear water.
Factory Glue
Rarely, glue from the tile packaging can get on the surface of porcelain tiles. This leaves a sticky residue that appears like globs of yellow crust, or like a recently removed sticker. Any solvent will remove this easily, and the yellow crust can be pried off with fingernails if there is only a small amount.
Check out this related video from Homesteady on Youtube.