Why Old Tile Grout Looks Black

It's frustrating to clean and clean and still that old tile grout just doesn't look any better. Why can't you get rid of that black stuff on old tile? As grout gets older and the cements start to break down, it becomes porous. Not only water penetrates, everything else in the water invades your grout too. That means body particles, soap dyes, and more get into your grout. When it dries, those particles remain.

Now you decide that this looks bad and start to clean it. Well now more foreign particles are introduced into your grout! So be sure to rinse, rinse, rinse.

Grout breaks down when these particles of soap (and whatever) expand and contract after getting wet, then drying, then getting wet again... Essentially they continually expand and contract until this water begins to infiltrate the substrate behind the tile and grout!

Not to worry if your home was built before 1968. Most likely you have concrete behind your bathroom tile. We refer to this as "mud tile" because it's real thick, maybe as much as 3 inches!

But if your home was built from the late sixties on, drywall was use and this can be a problem. The tile was glued to the drywall and the paper drywall surface acted as a wick absorbing water and holding it in suspension. As more water is introduced, mold and bacteria starts to grow. Soon this mold and bacteria come back through the grout exposing itself.

Then you wash it off and it comes right back within a week!

Believe it or not, this is telling you that something is really wrong so you certainly don't want to cover it up.

The worst case we've ever seen is where the builder put a plastic vapor barrier between the insulation and the drywall. The tile was then installed using a mastic glue. All of this plastic and glue holds even more water and rot and a musty, moldy, mildew smell started to pervade the room. The tiles actually started falling off the walls revealing the drywall which was soaking wet. This is also the perfect continuous water source that attracts insects such as black ants or silverfish.

Tear it out -- do not cover this up!

John Ashton, Founder
Baths Plus Inc.
513-821-7464