Installer Update: The Ins and Outs of Grout
January 1st, 2006


By Dave Gobis
Our favorite installation guru comes clean about grout. This what you need to know.

January-February 2006

Next to ceramic tile shade variation—which is inherent to all fired clay products—the largest, single customer complaint related to ceramic tile installation issues is grout.

Is it inherent also? To a degree, yes. Is it a valid problem relative to complaints received? NO!

Grout complaints in one form or the other are and have been the number one complaint from consumers and end users relative to installation as long as I have been in the business. This does not have to be an issue any more than the shade variation of ceramic tile when properly addressed. During the course of my years as a retailer and contractor I can say that in the sale of 10’s of millions of dollars in installed products, our complaints relative to grout shading can be counted on two hands. In dollar value, the loss was quite minimal. In 28 years we only once had to actually take corrective action. Bragging? Not at all. Our secret was that both our sales and installation staffs were properly trained and could read instructions.

The first step to happy customers and end users is the proper presentation of the product. This should include the same warranty as every ceramic tile sale: the color will vary; it is a promise and the only guarantee possible. Grout, with rare exception, will not perfectly match the sample. There are numerous reasons for grout color variation in both the installation and environmental areas. Those from a manufacturing side are few and far between.

From a sales perspective as a tile dealer, you are presenting a product for user approval under a specific set of conditions. If you are selling off of chip sets, you are showing a product that will in all likelihood be darker than the installed product. The short explanation is these samples are made in aluminum or plastic channels. These channels prevent the moisture from rapidly drying out. This slow drying time results in more intense color.

Several manufacturers also offer liquid latex additives in lieu of or addition to dry polymer formulations, another variation. The chip sets typically use latex additive if available. Most manufacturers realizing the futility of the perfect chip set for grout have gone to printed color samples. When it comes to printing, the limitations of ink and paper relative to variations in pigment, sand, and cement should be apparent to the professional. Installation environment as a whole is a big variable. To the consumer this is not the case; they expect it to look exactly like the sample. If you do not educate the consumer about these limitations during the sales process, you can be assured of receiving numerous complaints.

After the selection and sale there are numerous other items which can affect shading before the installer ever opens the bag. This list includes:

• Overglazed edges on the tile. This is a common practice done intentionally by some European manufacturers where the exposed edge is used as trim.

• Glaze on self-spacing lugs in wall tile.

• Porosity of the tile body. Impervious tile (porcelain) prevents the rapid absorption of water versus a wall tile which will readily absorb moisture.

• Dye lots. Grout manufacturers use multiple locations and blend numerous different colors during the normal course of production. Always check the dye lot. On larger jobs you should blend bags dry to achieve the greatest color consistency.

• Clean buckets and good potable water. The need for clean buckets should be self explanatory. Clean water can be hard to come by on construction sites with new wells. High amounts of chemicals, good or bad, can cause problems.

• Low speed mixing drill. Too much air results in weak grout. If you’re using a 3/8 drill, you are mixing too fast. Depending on the manufacturer, the range can be 100 to 300 RPM. (Yes, manufacturer recommendations vary.)

• Proper mixing and slake time are a much bigger issue than most can imagine.

Those are some considerations before we even mix the grout. Now that we are seemingly ready, but before we pour water or latex in the pail and add grout powder, a whole new set of installer controlled variables evolves.

• If a light-colored grout is to be used, hopefully the tile was installed with white thinset.

• The joints should be clean and free of debris including the construction dust typical of most job sites.

• The thinset in the joints should be of uniform thickness. Troweling parallel to the tile and positioning the next piece directly next to the previously installed tile makes this much simpler to achieve.

• The tile should be wiped down with a damp mop or sponge. Moistening the surface prior to installation goes a long way towards easier cleanup. Otherwise the tile surface’s first exposure to moisture will be the moisture in the pigmented grout. This is not a good idea.

• Tile setters do not own fans. Cement must cure at its own pace. Fans cause rapid loss of water resulting in light and weak grout.

• Caulk all movement joints and inside corners prior to grouting. In wet and exterior applications a sealant should be used.

Then there are those environmental concerns.

• Temperature should be consistent through the initial curing cycle to avoid mottling.

• There should be no exposure to direct sunlight. Heat accelerates the curing cycle and causes lighter color and weak grout.

• The installation area should be clean and free of dust and traffic. Gypsum dust is particularly miserable to remove.

• If the floor is going to be covered to protect it from traffic, it is all or nothing. Paper in the traffic areas or a box placed on the floor and left overnight somehow always results in the right color by damp curing the floor.

Now we are ready to mix!

Mixing offers a new set of variables. For some reason the low man on the totem pole seems to get the job of grouting. In Union Trades this job is called finishing. The pay scale is typically pennies below that of a setter, and the setter has a much larger tool investment. Proper grouting takes a fair amount of skill and understanding of the products. Assuming the tile has been properly installed, the person doing this job will give the consumer great pleasure in achieving their vision and providing a lifetime of easy maintenance. If the installer lacks the skills required, the customer will be presented with mottled, low, soft grout joints causing a lifetime of grief.

There is no substitute for the skill required to achieve proper joint filling, depth, and color. The lack of required skills is apparent to those of us on the technical end by the calls and emails we receive every day—and I mean every day. This is where things usually go sour.

By far the most common cause of grout complaints is excessive water. This can be either in the mixing process or clean-up. Proper drill speed and water ratio are very important to the thoroughly mixed product. Excessive speed results in too much air, causing pinholes, color loss, low compressive strength (powdery joints), and very little working time. The slower the better. Most of the water used in cement products is called “water of convenience”—that is, what is required to get it out of the bucket, on the floor, and in the joints in a reasonable manner. For the untrained installer, more water is more convenience. Why push that grout float and get a sore arm when we can almost pour it in the joints? Excessive shrinkage, poor strength (powdery), and mottled colors are the reasons why.

There is no corrective measure for poorly installed grout short of removal, though some may choose to argue. Repair will only mask the effects of a poor grout job. Grout floats are a very important tool, not only to compact the material into the joint but to clean the excess as well. There should be very little material remaining on the surface of the tile; this especially includes materials with surface variation. A good quality grout float is a little more expensive, but well worth the investment in time savings and job well performed. We prove this almost every week in our training courses. A good grout float will clean nearly all the residue off the face of the tile when used as a squeegee. Less grout on the tile, means less scrubbing and less water.

Water cleanup is the top reason for complaints on grout, period. I think we started using sponges in the early stages of the various latex and polymer formulations used in grout. I avoid using a sponge to clean a floor whenever possible. Yes, that is what I said—no sponge—and I still grout every week. There are times when a sponge in the cleaning process is necessary, such as a cold floor, a very sticky grout, unglazed tile or epoxy grout. The driest grouting clean-up method possible will result in the best performance and highest customer satisfaction for color and joint uniformity.

One method I use is called dry grouting. In this method once the grout has had a time to reach an initial set, meaning your finger can no longer compress the joint, it is time to begin cleanup. The first step is to “strike” the joint with an appropriate radius piece of wood. I have used everything from a closet pole to a Popsicle stick. This compacts the grout into a denser joint and leaves a perfectly uniform joint depth. Next, use a broom to lightly remove the excess material. Now you are ready to remove the remaining haze using either cheesecloth or my favorite, burlap. Using this method when possible results in uniform color and joint depth. It is also faster, easier, and better than sponge methods. There is no “final cleanup”.

If a sponge is used in cleanup the grout should also be firm in the joint. This may take anywhere from 10 minutes to a half hour, or longer. Getting back on the floor prematurely in the cleaning process will cause the joints to become low because the material is readily removed in this very soft state. The pigment used in many grouts is a powder with a consistency of talc and can easily be removed by excessive water or premature clean-up. When using a wet method, wring the sponge out as dry as possible, taking one pass to “shape” the joints, followed by rinsing and wringing out the sponge for the cleaning pass. Any remaining haze can be easily removed with a dry towel or cheese cloth.

There are many variations on wet cleaning of floors using towels, blankets, grout pails, even power sponges. In my opinion this part of the grouting process results in the greatest amount of complaints. These problems are easily avoided by not getting back on the floor too early in the initial drying process.

Since early on in my current position at CTEF, we have been involved in an ongoing research project with one major setting material manufacturer. Our initial research consisted of going through the numerous controlled variables mentioned in this article such as water use, mixing speed, drill paddles, and air entrainment among others. All were well borne out as factual concerns. On our second round, the chief chemist said he had made some improvements but the mixing time was critical, so we agreed to mix and slake the prescribed amount of time. The results were amazing to us. The stiff grout we had been accustomed to was gone, replaced by a consistency that I can only describe as troweling ball bearings. When we inquired what changes were made, the chemist told us that this was simply the first time we had actually mixed the product for the required amount of time. It seems the manufacturer had timed us at 2 to 3 minutes of mixing time after the lump free consistency had been reached instead of the recommended 5 to 10 minutes. I learned that lesson in spite of my 30-plus years of experience!

There are many new products currently out on the market claiming to be new and improved. There have, in fact, been some proprietary advances in epoxies, polymers, pigment, and aggregates. They do result in more uniform color in the many we have tried. But we have also found that with these new products come new installation techniques and waiting times. Mixing time and clean-up methods have become even more critical than with just good old sand and cement.

Grout is a subject that could no doubt fill a small book given all the products and cleaning variations in use today. This article is not meant to be a definitive look at the rights, wrongs, and how to’s of a complicated subject. However, it does cover the largest areas of concern based on the calls received at the Ceramic Tile Education Foundation and the Tile Council of America. Sales people need to better prepare their customers for the inevitable variation from the samples they use. Installers need follow instructions set by the manufacturers to minimize grout complaints. It is much easier and faster on the job over all to install grout correctly than incorrectly.

David M. Gobis, a third-generation tile setter, is the Executive Director of the Ceramic Tile Education Foundation. He has been in the trade for over 30 years and owned a successful contracting business for 18 years prior to his current position. Mr. Gobis is a member of the NTCA Technical Committee and ANSI A108, ASTM and TCA Handbook committees. He can be reached at 864-222-2131 or

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