How to Mix Grout
Time Required: Under 2 hours
Knowing how to mix grout is the first step in any new tiling project. This article will guide you through selecting the right type of grout and additives for your project, choosing the grout color and the process of mixing grout to help you achieve long-lasting, professional-looking results.
Grout has three main types: sanded, unsanded and epoxy. Since each serves a unique purpose, you will have to determine which of these three types best suits your project before purchasing the grout powder.
- Appears and feels gritty.
- Contains large grains of sand that help the grout bond and prevent cracking.
- Does not shrink significantly as it dries, thanks to the added sand.
- Used to grout seams that are 1/8-inch or wider.
- Not advised for use in seams that are thinner than 1/8-inch, as the sand particles may take up too much width and weaken the structure.
- Can scratch polished tile and stone. Test the grout on a discreet spot to see if it damages your tile or stone. If it does, consider using one of the other types of grout listed below. Sanded grout is less likely to scuff honed, matte tile or stone.
- Also sometimes called “non-sanded grout” or “wall grout.”
- Contains very fine mineral particles that have no noticeable grit, giving it a smoother texture than sanded grout.
- Used to grout narrow seams that are 1/6-inch to 1/8-inch wide. In seams wider than 1/8-inch, unsanded grout tends to crack without the boosted bonding power of added sand.
- Shrinks as it dries but shrinking is not noticeable in narrow seams.
- Tends to be stickier and easier to work with than sanded grout, especially for tiling on vertical surfaces.
- Good option for polished tile and stone, as it won’t scratch their surfaces.
Both sanded and unsanded grouts are cementitious grouts, which means their main component is cement. Cementitious grout is the most popular grout formulation and can be used for virtually any tiling project. This type of grout dries slowly, which allows it a long time to cure and develop maximum strength and durability.
One downside to cementitious grout is that it is somewhat porous; it is prone to staining and water damage if you do not properly seal it with a penetrating sealant after installation. For the best protection, cementitious grout should be resealed every two years.
- Not a cementitious grout. Epoxy grout is formulated with resin, silica fillers, pigments and a hardener.
- Can be used for seams wider than 1/8-inch.
- Does not need to be sealed. Epoxy is waterproof and generally less porous than cementitious grouts, making it a great choice for kitchens or other rooms where acid or grease stains are common.
- Dries quickly, which can be beneficial or challenging, depending on your skill level and the project difficulty.
- Can stain unglazed tiles, so purchase pre-glazed tiles or glaze them beforehand when using epoxy.
Confusing grout and caulk is a common mistake. While they are used in similar ways, the two materials serve different purposes and cannot be substituted for one another. Grout fills crevices in a flat surface on either a horizontal or vertical plane. It is typically not flexible enough to seal and hold corners between two different planes or between two different materials. (Epoxy can sometimes be an exception to this rule.) Grout will prevent the edges of tiles from cracking and chipping.
Caulk is a silicone, acrylic or latex formulation that can seal corners between two different planes and/or materials. Unlike grout, caulk is flexible enough to absorb movement, meaning it protects vulnerable areas like joints and corners from cracking. Also unlike most grouts, caulk is fully waterproof and prevents mold and mildew damage. Since it can adhere to most surfaces, caulk is generally more multi-purpose than grout; however, caulk will also eventually dry out and shrink, requiring replacement every few years, which makes it an ineffective substitute for the more-resilient grout.
Depending on your project, you may want to choose an additive for the grout. Common additives include colorants, sealants and latex.
- Colorants will determine the color of the grout. Many grout powders already have a colorant included, so you can select the color beforehand and not worry about finding another additive.
- Sealants are liquid additives that eliminate the need to seal (and eventually reseal) the grout after installation. Incorporating a sealant will waterproof and protect the grout for the rest of its lifespan.
- Latex additives make the grout more flexible and similar to epoxy. Including a latex additive will help prevent cracking as the grout dries and the tile installation settles.
Note that some grout formulations already have additives, so read the manufacturer’s label before purchasing one for yourself. Additionally, epoxy already contains all necessary additives, and adding more may disrupt its formula.
Whether purchasing a colorant or a pre-colored grout mix, choosing the grout color is an important step before you purchase or mix the grout. Grout comes in a vast variety of colors, so it is easy to match or contrast any tile. The grout color can be as bold or as neutral as you choose.
Many people prefer gray grout, as it is an unobtrusive neutral that coordinates well with most other colors. Grout that closely matches the color of your tile choice will give the sense of a flowing, continuous tile surface. Keep in mind that white or other light-colored grouts will stain more easily than dark-colored grouts and may darken naturally over time.
- Always check the grout’s manufacturer’s label first to find out how much powder you will need for your project and to see if there are any unique instructions.
- Measure out the grout powder and pour it into the empty bucket. If you are grouting a large surface, start with a fraction of the total grout you will need, and mix in small batches so that the grout doesn’t dry out too quickly.
- Add 3/4 of total water needed for the measured amount of grout powder.
- Begin mixing. Either mix by hand with the trowel or use the mixing drill with an attached paddle. When using the drill, mix slowly to avoid creating excess air bubbles that will weaken the grout.
- If you have an additive, incorporate it into the mix per the manufacturer's instructions.
- Soak the sponge in water and use it to squeeze more water into the mix in controlled amounts.
- Mix until all the dry grout powder is incorporated and no clumps remain.
- The consistency of the grout should resemble smooth peanut butter. It should be malleable, but not drip from the trowel when lifted. If the mix is too stiff or dry powder is visible, add more water. If the mix is too fluid and watery, add more grout powder.
- Allow the grout to sit undisturbed for 5 to 10-minutes. This allows the grout to strengthen or “slake.”
- After it slakes, briefly remix the grout to loosen it again and use immediately. Grout will completely harden after 30 to 60-minutes. If you wait too long after slaking, you will have to dispose of the batch and start again; adding water will not reactivate the grout at this point.
- Repeat this process as often as necessary to make enough batches of grout to complete your project.
- Epoxy typically comes in two parts: Part A, which consists of an epoxy resin mixture, and Part B, which consists of a mixture of hardeners. Some brands may have an additional part. Read the manufacturer's instructions to ensure you are using the appropriate tools for epoxy.
- Combine both parts in their entirety. Do not alter the proportions. Do not add water, a solvent or any other ingredient, as it may disrupt the epoxy’s integrity.
Tip: If you only need a little epoxy, then divide Part A and B into equal portions, such as 1/2 and 1/2. Never combine inequal portions.
- Mix slowly using a small, mixer drill paddle attachment until thoroughly combined. Scrape down sides of the bucket as needed to ensure all parts are incorporated.
- As with cementitious grouts, do not overmix or mix too quickly. Doing so will create air bubbles.
- Once completely combined, use immediately. You will have approximately 60 to 80-minutes to work with the epoxy, depending on the brand. Environmental temperature can affect working time and curing time. Cooler temperatures (below 60 degrees Fahrenheit) will extend epoxy’s curing time, while higher temperatures (above 90 degrees Fahrenheit) will significantly shorten the epoxy’s life and working time.
Now that you have successfully learned how to mix grout, you can move on to mastering DIY tiling projects. To learn more about grouting, read our guide How to Grout Tile here.