Ten of the Most Common Myths about Mixing Grout

By Heather Ruhl

Grout type can make a big difference in a flooring installation as not all grout is created (or mixed) equally. With so many new products available to meet industry demands, there are unsurprisingly quite a few myths about how to properly mix this composite material. Here are the top 10 misconceptions.

Myth 1: Temperature Makes No Difference
The temperature of the powder and water plays a role in how quickly the mixture will cure. Hot powder and water will cure more quickly than a cold mixture; however, the higher the temperature of these elements, the shorter the working time of the grout mixture. It’s best to stay within the temperature range provided in the product instructions and plan adequate time to complete the project.

Myth 2: Just Add Water
Adding more water than instructed will stretch out the time to work with the grout but it will also weaken the mixture as it changes its structure. This will eventually lead to cracking and colour inconsistency.

Myth 3: A High-Speed Drill Saves Mixing Time
Using speed might save time but it causes friction and heat, providing less working time with the grout mixture. Instead, mix with a low-speed (under 350 RPM) drill to avoid flash-setting grout.

Myth 4: Move the Paddle During Mixing as Needed
Lifting and lowering the mixing paddle can build up air in the grout mixture. The result is air bubbles and then pinholes in cured grout. Avoid whipping any air into the mixture.

Myth 5: Experience Allows for Eyeballing
Regardless of industry experience, always read product instructions, especially if trying a new material. Technology used in grouting products today might react differently to water than one might think. Some grout powders might look dry, for example, but gradually loosen up with mixing. Adding too much water upfront can weaken the structure of the grout, leading to cracking and colour issues.

Myth 6: Water is Water
The water combined with grout powder should be clean and potable. Dirty water or that with a high mineral content can cause grout discolouration.

Myth 7: Any Grout will Work
Grout is chemistry in a bag. Leaving a bag open on-site or in a truck exposes the mixture to humidity in the air. The cement component of grout will hydrate when there is moisture around. If this happens before installation, the grout might not cure properly after it has been mixed and placed.

Myth 8: Slaking Grout is a Waste of Time
Letting grout sit or slake after it has been mixed allows for optimal performance of the grout. Remember, it’s a chemical reaction. If the grout feels stiffer after slaking, don’t add more water. Simply remix the grout by hand again to loosen it up. And always follow the manufacturer’s instructions for slaking, since it’s different for every product.

Myth 9: Grout Additives are Useless
Grout additives are sometimes required for commercial and exterior applications to enhance grout performance in high-traffic or freeze-thaw environments. While there’s an additional cost upfront, these additives can extend the life of the grout and help protect the flooring or tile design.

Myth 10: All Grouts Mix the Same
Always read product instructions on mixing as there can be variations between grout types. There are three main types of grout: cementitious, epoxy and pre-mixed. Cementitious grout is mixed with water and additives, with a manufacturer-specified recipe for the mixture. No water is added to epoxy grout, which typically includes resin, hardener and sand. Pre-mixed grout is ready to go from the pail for an easy and reliable installation.

Heather Ruhl is training program manager at TEC Installation Systems, which provides floor preparation and installation products for tile, stone, wood, carpet and resilient flooring. TEC products are available throughout Canada.

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