Installations without cracks or loose tiles should be examined to determine if they can be restored, especially if located in a building with some historical or nostalgic importance. Almost any tile installation that has become unsightly through accident or neglect can be brought back to life using relatively simple methods and readily obtainable materials. The first step is to examine the tiles, the grout, and the movement joints to see if the installation is worth saving and restoring. The Inspection Tiles that are loose or are parting from the setting bed may exhibit cracks or a hollow sound. Loose tiles are either a sign that the adhesive grip no longer holds, or that there is a structural or support problem beneath the tiles. With a situation like this, no restoration of the tiles should begin until the problem with the structure is solved (without harming the installation). If the installation appears to be solid, with no visible cracks or loose tiles, examine the surface. If the tiles are unglazed porcelain, the appearance of scratches and even deep gouges in the tiles can be all but eliminated with grinding, polishing, and honing, since the color on the surface runs all the way through the body of the tile. The same fix, however, cannot be applied to glazed tiles since there is usually a contrast between the color of the glaze and the color of the bisque, or body, of the tile. Still, it is often a judgment call: worn tiles from a historic structure may be said to have character, but old, worn, white 4 1/4-inch non-vitreous tiles have little perceived value.
The Grout Joints A restoration inspection includes a close look at the grout and movement joints, if there are any. Normally, grout is not as strong as tile, and it may begin to erode and cause the unsupported edges of the tiles to spall or chip. Exposure to chemicals (usually acid-based liquids), and a maintenance schedule that includes high-pressure washes, are just two of the innumerable reasons grout joints fail. Grout installed prior to the 1980s or 1990s probably was not mixed with a latex to make it resilient and somewhat flexible, compared to regular, Portland cement grouts. This property makes latex grout ideal for partial repairs of old or nostalgic installations where excessive hardness is not desired in the grout. The soft material used to fill and finish the movement joints needs replacing from time to time, as part of regular maintenance of any ceramic tile installation. Removing Unwanted Grout If only a small amount of grout joint is affected, hand tools are used to remove the questionable grout. On joints less than 1/8-inch wide, a utility knife and an acre of patience is all that is required. Power tools can speed the removal process considerably. Reciprocating types can handle relatively narrow joints, while a dry-cutting diamond blade can plow through most grout joints with ease. If the tool is so equipped, it's a good idea to set the blade depth to about 1/16-inch below the bottom side of the tiles. After power sawing the joints, some work with a utility knife and a hand grout saw will be required. The resulting voided slot, filled with a latex grout, will result in a full, high-strength cross-section of grout that will endure much longer than a veneer of grout spread thinly over the remains of original grout that is not removed.
Cleaning the Tiles and Grout Joints If the tiles are securely bonded and the grout is relatively sound, the first restoration step is to clean the floor. If the floor is covered with paint or other types of coating, a non-slip overlay, for example, those materials must be carefully scraped away before the tiles can be cleaned. Chemical strippers may be used to remove some residues, but they can be noxious to use, and may leave behind residues that require additional treatment before the floor can be prepared for deep cleaning. For most grimy installations, I recommend a poultice made from a paste of water and powdered laundry detergent (with a bleaching agent if the grout is white). Using a margin trowel, a clean 5-gallon bucket, and a margin trowel, slowly add water to the powder and stir gently to avoid foaming the stuff-it needs to be stiff enough to hold peaks so that it can be applied in a 1/4-to-3/4-inch layer over the entire area to be cleaned, but it also has to be wet enough to penetrate into the grout, and into the minute surface crevasses of the tiles. To remove lumps once the entire batch has been hand-mixed, I may use a grout-mixing paddle chucked in a slow speed drill to finish the mixing. The poultice is then spread evenly over the tiles with a trowel, and immediately covered over with plastic food wrap to prevent evaporation. The poultice method is an age-old method for removing stains from stone floors, and it can be very effective when applied to a ceramic tile floor. To do this, the poultice must be allowed to do its work unhurried. I spread about 10 square feet, and then cover with the plastic film before spreading more paste. Windows should be shuttered to exclude sunlight, and the ambient room temperatures should be as low as possible to help retard evaporation-the method is effective only while the paste is still moist and water-laden. Once the moisture is gone, very little additional cleaning occurs. Normally, I let the poultice remain on the floor for as long as a week before removing it. First, I remove the plastic film, and allow any remaining moisture to evaporate. Next, I use a soft plastic scraper and a vacuum to remove the encrusted detergent from the tiles, and then switch to a soft white scrubbing pad and some water to dissolve what remains on the surface. Finally, I rinse the floor with clean water and a sponge, and allow the floor to dry. With heavily stained tiles and grout, I sometimes apply a second or even third poultice until I get the desired results. When the tiles and grout joints are bone-dry, I install any grout that is needed (and allow it to cure and dry fully), and then I treat the floor with an impregnator to help reduce future staining and maintenance. The poultice/impregnator method works well on grout and both ceramic and natural stone tiles.