Working With Grout

We’d like to give you a little more information on working with grout…. a few hands on tips for applying and wiping grout on your tile job.

At this point in your project you have properly bedded your tile pattern with a thinset adhesive over an appropriate setting surface, allowed it dry over night, and have removed setting spacers. Now you’re ready to grout the job. As we’ve already discussed, unsanded grout is used in small joints of less than 1/8 th inch and sanded grout is used in 1/8 th inch or larger joints.

Clean the surface:

Before you mix grout, you need to clean the tile surfaces and grout joints to remove excess thinset or any other unwanted debris.

On some construction sites, other elements like sawdust or drywall mud splatter invade the joints. You could use a shop vacuum first if this is the case.

To wipe the joints, you’ll need a large bucket of cold clean water, a large tile sponge, and possibly a retractable knife, a small stiff putty knife, and/or a hand held thin profile grout saw.

Wet the sponge and wring it out as dry as you can. Excess water in the sponge will leave too much water in the joint, which will cause problems later.

Wipe the joints to remove most of the excess thinset, rinsing the sponge frequently. For larger remaining clumps after the first wipe, gently scrape with a stiff putty knife on the surface of the tiles or use the retractable knife blade or grout saw inside the grout joint.

The first wipe wets the thinset so it comes off much easier. Be very careful not to damage the tiles with hand tools. Thin blades must be held in line with the joint, especially in very thin joints. Any turning of the blade in a narrow grout joint will chip the tile.

In addition, be careful not to strike tile corners at grout joint intersections. Just be gentle.

If you’ve done a good job of wiping excess thinset during the setting phase, this cleaning job should go quickly. The whole idea is to have fairly clean joints to hold the grout. Excess thinset in the joint will become visible when you wipe the grout.

Mixing the grout:

For most residential jobs, hand mixing is adequate. Only for large jobs with more than one worker would you need to mix a large amount of grout with a mixer. I like to use a one to three gallon bucket and a 6” margin trowel for most jobs.

Use a good quality grout, which contains dry latex additives. Each bag of grout has thorough instruction on grout mixing. Read and use the manufacturer’s instructions. On very specific applications, like near heat or on outside jobs, consult the manufacturer’s 800 number for specific details.

On most jobs, good quality grout mixed with water is sufficient. Alternately, in areas where added durability or water resistance is needed, you may want to mix grout with a latex grout additive or “milk” as provided for by the manufacturer.

Start the mix with a little liquid in the bottom of the bucket. Add a portion of dry grout to it and stir it a little. Add more liquid a little at a time until you get to the right consistency. The right consistency may vary a bit depending on the type of grout (sanded or unsanded) or the application (floor, wall, countertop, etc.) Generally, grout should be just loose enough to flow easily into the joint, but stiff enough to stay in place without excess liquid.

Unsanded grout for a wall should be no thicker than smooth peanut butter and no looser than toothpaste. Sanded floor grout can be a littler looser, but not sloppy or runny.

Run the margin trowel through the grout in the bucket. If it is stiff like a clod of wet dirt, it’s probably too dry. If it slumps too quickly and doesn’t stand up or peak, it’s probably too wet.

When mixing, don’t ignore “slaking”. Slaking is a process of thoroughly mixing and then letting the mix stand or rest before remixing. Slaking allows the pigments and additives to completely incorporate in the grout.

After the first mix, the grout will stiffen quite quickly. But with the second stirring the mix will loosen up again. During grouting, stir the mix often to keep it loose, but never add more liquid later to loosen an old mix.

Using a grout float:

With the right mix and a good rubber grout float, the grout should flow deep into the joint.

For floors, pour or scoop out a portion of grout from the bucket onto the floor. Floor grout, especially sanded grout, can be fairly loose, but not soupy. Hold the grout float at about a 45-degree angle relative to the floor and sweep across the tile surface at about a 45-degree angle relative to the grout joint grid. This will allow the float to pass across the tiles removing excess grout where it is not needed. It also allows the float to pass across the joints without getting hung up or trapped in the grout crevasse.

As you go, make sure each vacant grout joint is filled completely. Work an area that you can easily reach from one kneeling position, and then move to an adjacent small section. Fill overlapping sections one by one while backing your way out of the room.

For walls or vertical surfaces like fireplaces, the grout needs to be mixed a little stiffer to stay in place. For rare ceiling applications, make sure the grout is mixed somewhat stiff, but not clumpy. The water in the grout will aid the product in sticking in place with a capillary action.

Even with the ideal mix, it’s hard not to get messy with ceiling grout.

In many applications you will be using unsanded grout for wall work, like tub and showers with small 1/16th inch joints. Unsanded grout on walls needs a little extra push to insure that the grout goes all the way down into the joint. You can start with sweeping motions across the tile surface applying most of the grout. But then go back over each horizontal and vertical joint in the section with the short end of the float to make sure the joint is filled and there are no voids. Start at the bottom of the wall and work in sections to the top. It’s easy to miss spots, especially with unsanded grout, if you don’t keep yourself at eye level with the work.

Wiping the grout:

Once you have floated-in the grout, you’ll need to consider the wiping process.

Timing is very important in the wiping process.

If grout is mixed properly, it should stay workable in the bucket for a good while. But once it is spread, it will start to cure or dry.

As you move from one section to another while applying the grout, you will see the first sections drying. If you wait too long, the wiping process can become very difficult. If you see the grout becoming quite dry and hard while you grout, don’t hesitate to stop grouting and do an initial wipe on those areas. The grout in the bucket will stay workable while you tend to the drying grout.

I like to wipe grout in about three steps. With each wipe, use clean cool water. Warm water with cement-based products will chemically accelerate the cure. Always use the large yellow sponges specifically designed for tile work. Wet and clean the sponge completely and then wring it out completely with each wipe. The idea with wiping is to remove excess gout from the areas you don’t want it, and to leave it in the places you do want it. The sponges have a hydraulic action, which pulls the material into the sponge, if it is not real wet. If the sponge is too damp, the excess water will push the materials away from the sponge leaving it on the surface.

The first wipe can be done within 20 or 30 minutes. With this first wipe, concentrate on wiping the excess off the tile surfaces and less emphasis on wiping the joint. Excessive wiping in the joint at this point when the grout is still tender will remove too much of the grout in the joint. As you go, look for voided or low spots indicating joints that didn’t get filled. Keep the grout bucket nearby and fill voids as you see them.

After another 30 minutes or so you can do a second wipe with clean cool water. This time the grout is a little tougher and you can start wiping along the grout joint, which will pull them straight and smooth the top. You shouldn’t need to apply a hard scrubbing action. Just draw the sponge gently in line with the joint a few times to make a neat and smooth grout line. Let the action of the damp sponge do the work.

The technique in the third wipe is important. By this time you should have a fairly clean tile surface and full, straight and smooth grout joints. Usually, however, there is a hazy or chalky residue left behind. Start your third wipe with clean cool water and a barely damp sponge. Now with one side of the sponge, and with only one stroke, pull the sponge toward you across the tiles. Turn the sponge over on the clean side and again with only one stroke, pull the sponge toward you. After only one wipe on each clean side of the sponge, rinse the sponge and wring it out completely. Continue this process over the entire surface. The idea is to make the sponge work to lift as much of the residue as possible. Any re-wiping with a dirty side of the sponge will only reapply the residue.

During all of the wipes, always look for voided areas or places where excess thinset is protruding through the grout surface. Keep the grout bucket handy and repair these areas as you go. Now it’s time for a break while you wait for this final wipe to dry out. After an hour or so and using a clean dry towel, lightly polish off the final hazy residue.

Caulking the job:

Caulk can be used in some places in most any tile job. Caulk is always a part of tub and shower tile jobs. Caulk is manufactured in both sanded and unsanded types and comes in colors to match most any grout.

On floor jobs use caulk at places where the tile meets dissimilar materials like at cabinets, thresholds, stair noses and baseboards.

Countertops can be caulked where the top meets the wall or backsplash and at the sink.

Caulk is always used at inside corners and at the bases of tub and shower surrounds.

Caulk should not be applied over wet grout. Wait a day or two to caulk over fresh grout. If you’re in a hurry and need to caulk the same day, do not grout the areas that will be caulked so you don’t seal in moisture from wet grout in areas like where the tile meets a tub or a shower base.