Cleaning Grout

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How do I clean grout?

Cementitious grout, as you may have observed, is porous – it can absorb a stain. Looked at under a microscope, there is a large surface area to absorb stains. For this reason, many owners choose to seal their grout – usually the better the sealer, the more the grout joint is protected. Even better, if epoxy grout is used, it is virtually as stain proof as the tile.

Removing stains from cementitious grout is similar to removing stains from clothing. The same cleaners you might use on clothes to get out a stain should also work on grout.

Keep in mind though, that grout is based primarily of cement and sand. Sand, like glass, is unaffected chemically by most cleaners. Cement is not – rather it is alkaline based and is dissolved by acids. As baking soda and vinegar react, so do grout and vinegar.

Accordingly, it is better to clean grout with an alkaline cleaner (Spic and Span, Mr. Clean, etc.) than an acid based cleaner. There are also specialty cleaners available at most tile retailers that are designed for tile and grout. There are also cleaners with enzymes that attack stains similar to enzyme pre-soaks for laundry.

The same cleaner that works on the grout generally will work well on the tile. In fact, since the tile is usually so easy to clean, the tile can often be cleaned with water.

Just a few more important points: As the grout can absorb the soap as well as a stain, do not clean with oil or wax based cleaners (Murphy’s Oil soap, Pine Sol, etc.). These products will leave a waxy or oily film in the grout. Even good alkaline cleaners, if not properly rinsed, will leave a sticky soap film. This usually attracts dirt. In fact, truly clean ceramic tile without any sticky soap film will stay very clean as tile does not tend to hold an electrostatic charge (which can attract some kinds of dirt).

The absolutely best way to clean grout is to apply the cleaner and then vacuum (“shop vac”) up the dirty water. This lifts the dirt off the joint. Apply rinse water and vacuum that water up. This lifts off any remaining soap film.

Just to mention it, there are tile installers that remove very stubborn stains on grout with an acid (like straight vinegar or a stronger acid). There they have elected to dissolve the top layer of grout molecules so the stain is no longer attached to anything. While this works, it is not recommended by the grout manufacturers – needing to regrout is sometimes the result. Also, extreme care should be used when handling any acids.

Should you be unable to get your grout clean through conventional methods, you may also want to try steam. Some stains that do not respond to conventional cleaners will come clean when subjected to pressurized steam. As a last resort, some installers elect to cut out the grout and regrout. This is possible although care must be taken to not damage or loosen the tile. Generally it is not possible to grout directly over the old grout without cutting the old grout out. The same contaminants that made the old grout dirty may prevent new grout from sticking properly.

How can I prevent my grout from staining?

To prevent staining in the future, you should seal the grout.

Generally, sealer is a very good idea for cementitious grout (regular grout – not epoxy grout). For glazed floor tile, it is not a good idea to spray anything on the tile – the glaze of the tile will be easier to clean and longer lasting than any coating. For unglazed tile, generally sealers are recommended, although it is important to follow the recommendations of the tile manufacturer.

For cementitious grout, there are two broad classes of sealer: penetrating sealer that chemically bonds with the grout and repels water (and water based stains) and topical sealers that coat the surface of the grout and repel almost everything (until they are worn off by foot traffic).

Each type of sealer has its advantages and disadvantages. Additionally, there are hybrids on the market combining advantages.

In general, the topical sealers are less expensive but give the grout a plastic appearance. Also, they are subject to wear and tear and very sensitive to water in the grout while curing. As stated above, the plastic coating does block almost everything until it is compromised by foot traffic.

The penetrating sealers are more expensive but also more durable. There are also penetrating sealers that repel oil based stains that are even more expensive. They can be applied on the grout sooner than the topical sealers, as they are usually vapor permeable. As they do not coat the grout (but penetrate in), they do not change the large microscopic surface area. While stains don’t penetrate, they can be a little harder to remove (just a little) because the sanded texture of the grout hasn’t been changed.

How do I clean off the “white stuff” on my grout?

Solving the problem of residue on grout depends greatly on the cause of the problem – with ongoing moisture migration through concrete being the most difficult.

Generally efflorescence is removed with an acid. However, grout manufacturers do not advocate the use of acids because they attack the cement in the grout. Used judiciously though, this can be a highly effective way of removing efflorescence. There are several products on the market for this with different acids and strengths. In all cases, extreme care should be used to protect the person applying the acid and surrounding fixtures. Generally, it is best to employ an experienced professional for this type of work. Also, acid that is too strong can strip some color out of grout (which is also undesirable) and acid generally cannot be used if acrylic sealers have already been applied to the grout.

After successfully removing the efflorescence, it can only reappear if moisture is entering the system. At this point, sealing the grout joints with a penetrating sealer may be recommended depending on the entire tile assembly. The sealer will minimize water entering from above (for example, from rain) and slow down the rate of evaporation of the water entering from below. However, they should not be used if a water sensitive material (like mastic and some self-leveling products) was used in the tile assembly and there is water migration through the substrate.

For removing a whitish residue from polymer migration, solvents or strong cleaners are needed. As there are many different polymers that could have been used in the grout, any one cleaner may have more or less efficacy. Possibly, an acid could work by removing the surface layer of grout molecules to which the polymers are attached. For removing soapy dirt stuck to the grout, generally multiple rinsing with clear water and some brushing of the grout joints will be effective. As noted previously, vacuum extraction (for example, with a shop vac) provides the easiest and best results.

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