How to Clean and Restore Grout

Dirty grout dramatically detracts from the floor appearance. However, all is not lost. With the right combination of chemicals and cleaning techniques, you might be able to get the grout back to a like-new appearance. In this article, we take an in-depth look at grout cleaning to help you improve your floor’s appearance.

WARNING: Any time you’re using a new cleaning process, test the process in an out-of-the-way area. Take the time to establish that the process you’re using works and won’t damage your floors before moving on to the rest of the room.

SAFETY WARNING: Follow the manufacturer’s instructions when using chemicals, including personal protective equipment and proper ventilation.

All About Grout

Before we cover how to clean grout, let’s cover what grout is. There are two types of grout, cement-based and epoxy.

Cement-based grout – This grout consists of concrete, water, and sometimes sand. You may see this kind of grout referred to as sanded or non-sanded. Adding sand to the grout increases strength. Wall tile installations, which have thinner grout lines and require less strength, use non-sanded grout. Floor tile installation use sanded grout, where the grout lines can be between 1/8-inch and 3/8-inch wide.

Cement-based grout is porous and absorbs moisture. Dirty water soaks into the grout giving it a poor appearance. Using an automatic scrubber, rather than a mop, on grouted tile helps remove the dirt before it can soak into the grout. Also, making sure your scrubber’s squeegee performs well can help dry grout lines. Check out this article for tips on optimizing squeegee performance.

When the grout is newly installed or freshly cleaned, apply a sealant to protect against moisture absorption. Sealants come in two varieties, penetrating and non-penetrating. Non-penetrating sealants don’t absorb into the grout and offer less protection than penetrating sealants. A penetrating sealant will absorb into the grout, reducing the grout’s porosity, making water bead on the surface. When applying any sealant, be careful to avoid getting it on the tile because it will leave behind a hard to remove haze. Always refer to the manufacturer’s instructions when sealing the grout to ensure that the products you have selected are appropriate for your flooring. Sealants wear out over time, so cleaning the grout and reapplying sealant is a typical restorative process.

Important! Never apply a water-based floor finish to grouted floors. The floor finish will penetrate the grout, and it will be impossible to restore the grout to the original appearance.

Epoxy-based unsanded and sanded grout – Epoxy-based grout uses a polymer, instead of concrete, to create a hard, waterproof, stain-resistant filler between tiles. It is easy to clean and does not require a sealant. It is also very durable. With these benefits come a few tradeoffs. Epoxy-based grout is more expensive and takes longer to install. Also, epoxy-based grouts can have a “plastic” looking appearance, which some people find undesirable.

Before you start, inspect your grout

Here are a few questions you need to answer before you start:

1. Is the grout sealed? Apply a few droplets of water to the grout in various locations. If the water beads on the surface, then there is a sealant. If the water absorbs into the grout, there is no sealant or the sealant layer has broken down.

2. Is there mildew or mold on the grout? If the tile is in a frequently moist area with poor circulation, some of the dirt may be due to mold or mildew. Mildew is a type of fungi with a white or grey appearance. Mildew can look powdery or fuzzy. Mold also refers to a kind of fungi that is usually fuzzy or slimy-looking and can be various colors; blue, green, yellow, grey, or black.

3. Is the area greasy? If there is grease on the floor, you will need to select chemicals capable of cutting through the soil.

4. Inspect your grout for damage. Cracks can indicate possible problems with the grout’s installation. If the grout is loose, agitation might break it away from the floor. Unless you are ready to replace the grout, you might need to use more gentle methods around damaged areas.

Restoring Grout

Clean the grout using the least aggressive method possible. Remember that grout is a granular material that can react with some acidic products. Use nylon brushes instead of wire brushes to minimize damage to the grout. Try using neutral pH chemicals before using acidic chemicals.

Step 1: If you have mold or mildew, kill it first.

Use an anti-fungal surface cleaner to remove and destroy the fungus on the grout. You may find that killing and eliminating the mold and mildew restores the grout to an acceptable level. For stubborn areas, use a nylon brush along with the chemical to try to remove stains. NOTE: Unless you remedy the moist conditions that caused the mold to appear, it will come back. For a more permanent solution, you may need to improve ventilation or prevent moisture accumulation.

Step 2: Try cleaning the grout with a nylon brush and a general-purpose cleaner or a degreaser

Use a general-purpose cleaner or a degreaser and a nylon brush to clean the grout. If the grout sealant is intact, the dirt should be sitting on top of the grout surface. If you have greasy soils on the floor, you may need to opt for a degreaser that is safe for tile and grout. For large areas, use a floor machine or floor scrubber to speed up the process. You may also want to incorporate a high-pressure tile and grout cleaner, like the Rally 1200, into this step.

Step 3: Try using a chemical designed explicitly for tile and grout cleaning

If steps 1 and 2 didn’t produce satisfactory results, it’s time to bring out the harsher chemicals. Tile and grout cleaners typically will either have a high pH (Alkaline) or a low pH (Acidic). Whichever one you choose, read all the instructions before starting. These chemicals will have additional precautions. For example, one alkaline tile and grout cleaner recommends keeping the chemical off glass, aluminum, and steel. Acidic cleaners can react with the concrete in the grout. Follow the manufacturer’s recommendation regarding dwell time to prevent an over-reaction with the grout.

Use either a wet/dry vacuum, floor scrubber, or the Rally 1200 to remove the grout cleaning chemicals. These methods remove the soil and chemicals from the floor by vacuuming them into a recovery tank, preventing further reaction of the chemical with the grout. Finally, rinse the area with water and vacuum away any remaining soils and chemicals.

Save labor with the right equipment

Wet/Dry Vacuum

Floor Scrubber

Tile / Grout Cleaner

Keep your grout looking great

Cement-based (non-epoxy) grout can be sealed to prevent future stains. Your local janitorial supplies distributor can help you select the right sealant for your situation. Sealants are either topical, sitting on the grout’s surface, or penetrating, soaking into the grout. Topical sealants are less expensive but not as durable as penetrating sealants.

Avoid mopping grouted floors. Mops will deposit dirt into the grout. Use a cleaning machine instead. There are a variety of floor scrubbers that will fit any application. Alternatively, the Rally 1200 uses a high-pressure spray to turn a spray bar at 1400 RPM and blasts away the soil. A vacuum shoe around the spray tool sucks up dirty water, leaving clean grout lines behind.

Your local NSS distributor is an excellent source of information when selecting cleaning machines. In addition to your local distributor, NSS has regional managers throughout North America to help steer you in the right direction. Use the “Start a conversation” button on our homepage to let us know who you are and where you’re located. One of our regional managers will reach out to consult with you about your cleaning operations.

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