#MAPEITechTip: Specifying the ‘right grout’ for the ‘right application’

No other piece of real estate has been at the center of more heated discussions between husbands and wives, designers and installers than the lowly grout joint.  Who would have thought that choosing a grout color and deciding on the size of the joint (typically 1/16" to 1") could raise such a ruckus, often more than selecting the tile, stone or glass itself!
 
And yet when the right grout is selected for the job (color, chemical and stain resistance, size), it fades into the aesthetic of the tile or stone installation. That is, until there is a problem with the grout, and the installers phone begins to ring off of the wall—complaining of color variations, staining, cracking, powdering, or chemical attack does everyone turn their attention to that small piece of real estate again. 

That is why it is important to look beyond color and joint size to determine if the right grout is matched to the right application.  Let’s take a look at the most popular grouts available to see the benefits and limitations of each grout make-up. 
 
Cement-based grouts can be an economical and aesthetically pleasing solution to many tile, stone and glass installations. However, using too much water either in mixing or in the cleanup process increases the potential for efflorescence (efflorescence occurs when soluble salts rise to the surface and powder out on the grout joint surface) in Portland cement-based grouts (Keracolor S or Keracolor U). That is why it is key to only use the amount of water indicated on the Technical Data Sheet (TDS) or on the packaging. This guideline also applies during the cleanup process—wring out the sponge so that it is wet/dry, not dripping wet.  Over wetting or scrubbing the grout joints with excessive water, could lead to ‘efflorescence’.  If you still want to use a cement-based grout, but are concerned about 'efflorescence', use MAPEI’s Ultracolor Plus FA grout, which uses calcium aluminate technology in place of Portland-cement-based cement, these type of cements do not contribute to 'efflorescence' and the final joints are more color consistent.
 
Whether using a Portland-based or Calcium Aluminate cement-based grout, good installation practices are required to ensure a grout joint that is strong and aesthetically pleasing—temperature, humidity and wind can affect the appearance and strength of a grout.  That is why it is good to keep in mind, particularly outside, that cement-based grout cures best when installed between 70°F and 80°F with 50% relative humidity. While this temperature is optimum, these grouts can be installed in temperature ranges from 50°F to 100°F. What about the mixing water?  Using water directly from the hose that has been baking in the sun or using pond water will negatively affect workability as well as the end product.  This also goes for the powdered grout itself, pulling it from the back of a truck or van that has been baking in the sun or in sub-zero winter, without acclimating it, could cause problems not only with the installation but with the grout results as well. For this reason, MAPEI recommends providing a minimum 24 hours for acclimation prior to application.
 
Because both standard and high performance cement-based grouts (ANSI A118.6 and A118.7) are porous (typically in the 5% to 18% range of water absorption), they are more susceptible to staining, since the pores offer a reservoir for dirt and spills.  In addition to selecting a premium grout, using a grout additive or grout sealer to improve stain resistance will help in maintaining the look and performance of your cement-based grout.  If the grout will be exposed to daily staining and cleaning regimens in kitchens and bathrooms—add MAPEI’s Grout Maximizer (Keracolor™ S or Keracolor U Only) in place of water to increase resistance to water, dirt and common household stains. If additional protection from staining is desired for the grout joint as well as for the tile or stone, use one of MAPEI’s UltraCare™ sealers once the grout (Ultracolor® Plus, Keracolor™ S or Keracolor U) is cured and ready for a sealer.

Are there limits to cement-based grouts where another type should be selected for the application? Yes, epoxy grouts will always outperform even a high-performance cement-based grout (Ultracolor Plus; ANSI A118.7) due to their low porosity (0.4%), high resistance to chemicals, stains and rigorous cleaning regimens.  When harsh conditions are specified, an industrial-grade epoxy grout is required– such as in an as industrial, commercial and institutional wall and floor installations, like a commercial kitchen or dairy plant. Kerapoxy® IEG CQ provides high chemical and heat resistance, while being able to withstand routine cleaning regimens. This type of industrial epoxy grout is perfect in commercial kitchens exposed to oleic fatty acids, heat and enzymatic cleaners. Even though these industrial epoxy grouts withstand these environments, it is still required to utilize a clean water rinse so remove fatty acid residue after maintenance.

What about the dining area of a restaurant that will not be exposed to the same harsh environment? Kerapoxy CQ is a great fit, providing excellent stain and chemical resistance from restaurant patrons’ daily spills and foot traffic.  Do not expect all epoxies to perform the same. Each epoxy is formulated to handle specific chemicals, cleaners and service duty. For applications ranging from residential to heavy industrial, it is critical to match the right epoxy to the right application. Always consult the manufacturer’s technical data sheet to determine suitability for the specified installation and chemical exposure.

What about premixed grout (mastic) in a bucket that you see at many box stores—can they be used anywhere you use a cement-based grout or epoxy grout?  In a word no, these grouts grouts are formulated for dry to intermittent wet conditions (water causes them to break down and emulsify) where very little water will be present, such as a backsplash or tub surround. Depending on the formulation, some premixed grouts can be used on shower floors for residential applications. 

Within the tile and stone industry there was a desire to have the ease of a premixed grout in a bucket, while performing similar to a cement-based or epoxy grout.  In recent years, manufacturers have been able to meet this challenge with acrylic and urethane technology that takes premixed grouts to the next level, providing strength, stain-resistance and chemical resistance.  All of this from a re-sealable container that can be used on future repairs or other projects, saving time mixing and waste.
 
MAPEI met this challenge head on with a ready-to-use for both commercial and residential installations—MAPEI Flexcolor™ CQ grout was born for interior and exterior applications. This grout can be used straight from the re-sealable bucket on walls and floors (grout joints 1/16" to 1/2"). MAPEI uses coated quartz (CQ) aggregate technology to ensure color consistency while improving application time and cleanup. For both the homeowner and the installer, it is a win-win scenario, not having to mix, wait, mix and mix again cement-based grout, wait for the grout to dry sufficiently in the joint before washing, greatly increasing efficiency—without sacrificing performance (no efflorescence) or the end look of the grout.  All of this with increased stain and chemical resistance!  It even can take as much as 65% less time for installation when compared to traditional cementitious grouts. What was considered impossible just a few years ago is now a viable choice when selecting a grout type, without compromising.
 
The key to any grout job is to remember, that although all grouts do the same job, fill the space between tiles, they can have very different features, benefits and limitations. Some grouts are more economical, while others are designed to save time and provide ease of application. There are even some grouts that are formulated to perform in the harshest of environments and chemical exposure. When selecting a grout, qualify the “service environment” using the TCNA Environmental Exposure Classifications; Com 1-7 & Res 1-7.