QUESTION

Why is our matte gray colored porcelain floor tile turning several shades darker?

The floor tile was installed four years ago throughout our condo unit. We recently removed an area carpet in the living room and discovered that the underlying tile retained the original gray slate color while the surrounding tile had evidently turned several shades darker in contrast. An examination of the naked tile in the other rooms throughout the condo also indicated a uniformly darker contrast from the original color. The installation was over a masonry floor that had been left exposed in a very dry Las Vegas climate for several years before finishing. We did not over seal the finish. What is causing this effect and how can we restore the original color?

ANSWER

ANSWER - Although by definition a porcelain tile is impervious, it can still get dirty.  Depending on what kind of texture the tile has on its surface and whether it has micro pores, as many do, some porcelain tiles can have a tendency to collect dirt and not clean easily.

There is a trade off with tiles in terms of being slip resistant and how easy it is to maintain.  The more texture a tile has the more it will be slip resistant, but the more it will tend to collect dirt and require more effort in maintaining it.

Also some porcelain tiles will have microscopic pores where dirt can get trapped in them.  During the firing process of the tile in a kiln there is an off-gas where microscopic pores can develop in the tile.  Depending on how the manufacture treats the finished side of the tile, some tiles can have a propensity to collect dirt.

What you described between the clean virgin tile under the carpet, and the tile exposed to traffic, is not uncommon.  People tend to just damp mop floors and they don't properly rinse the floor and pick up the dirty water.  So they end up moving dirty water around and letting it dry on the tile surface.

To properly clean tile you should use a detergent or degreaser made for tile to let it soak into the floor and then use a bristle brush with an extended handle and scrub the floor.  Then use a wet and dry vacuum to pick up the dirty water.  Then rinse the floor with clean water and pick it up with the wet and dry vacuum.

Even though you have porcelain tile that is impervious, using a sealer over it once it is clean and dry will make the tile easier to keep clean.  It won't tend to pick up dirt and will be easier to clean.   Use a tile sealer for porcelain tiles.  Since it doesn't absorb, apply the sealer with a damp lint free cloth, and then immediately wipe it up and buff dry it with a dry lint free cloth.  If you leave the sealer on the tile surface without wiping it dry, it will make it tacky and cause a cleaning problem.