Grout is often dirty due to the fact that it is recessed. When a floor pad or brush is used on the floor, it simply glides over the grout and never touches it; hence, not cleaning it. In order to get into the grout, you’ll need a brush that will reach down into the grout lines. There are several manufacturers that make these types of bushes.
Another way of reaching into the grout is to use a machine with a rotary brush. There are also several manufacturers that produce these machines. Of course, if the floor is small enough, you can always scrub the grout by hand with a narrow scrub brush.
Now, once you have the proper brushes and machinery, it is time to choose the proper chemicals. The main reason maintenance personnel have difficulty cleaning grout is because of improper chemicals. Grout becomes dirty and soiled by acrylic finishes and excess cleaners collecting in the recesses. In addition, the grout also accumulates dirt from traffic. In order to clean the grout effectively, two different chemicals are needed. Acrylic finishes and excess cleaners can be removed using a standard floor finish stripper. The dirt can be removed using a mild acid wash. The following is an eight-step grout-cleaning process. Do not use this procedure to clean grout on marble floors.
The above procedure should clean most grout. If it doesn’t work, then the grout may need to be replaced.
A word on sealing grout: One of the best sealers for grout is what is known as a penetrating sealer or impregnator. These sealers are sold for protecting marble and stone, but also work to seal grout. They are easy to apply by mopping the sealer over the entire floor (tile and all). The sealer will flow into the grout joints. The excess sealer is removed from the tile by wiping with rags or buffing with a white pad or carpet bonnet.