Grout problems in tile and stone installations are a leading cause of both customer complaints and callbacks - with color inaccuracies high on the list. The problems can lie in the product itself, or in the installation process, or both!
The key is to understand why grout color can change and how to keep it from happening. The best bet is to become more knowledgeable about the way some grouts are formulated to help neutralize traditional color problems. It's also important to revisit successful grout installation techniques.
A growing sector
Based on a number of industry and government reports, demand for premium hard-surface floors is growing. Ceramic tile is projected to grow at a 5.8 percent annual rate on a square footage basis between 2005 and 2007, according to recent data from the Catalina Report on Ceramic Tile. The U.S. Geological Survey, meanwhile, reports that imports of natural stone flooring have risen at a steady rate of 15 percent since 1996. In short, there is significant interest in ceramic tile and stone surfaces - all of which require grout.
Customers who choose tile and stone floors are emotionally and financially invested in their surface and expect the beauty they saw in showrooms, magazines and store brochures to translate to their homes.
When it comes to grout, they expect the grout color to match what they saw in the store. Customers choose grout color based on color samples. They will notice after installation if the grout color is wrong or inconsistent.
Installers, meanwhile, need grouts that help them deliver accurate and consistent color and are also easy to use. In the end, everyone benefits from a quality job - the customer, the installer, and the flooring retailer.
Understanding color accuracy
When it comes to grout color, it's important to understand the concept of grout color accuracy. By definition, it means the grout installed matches the color sample used to select the grout color. Grout color accuracy depends heavily on the grout manufacturer's level of quality control. Color variations can occur when:
• An improperly formulated blend of materials will not cure to the correct color.
• The manufacturer does not allow for differences in raw materials and processes at different locations.
• The manufacturing process itself is not consistent.
• Color is not closely scrutinized, or the tolerances that define "acceptable" are too wide.
Leading grout manufacturers ensure accuracy by applying color science and computerized technologies to their quality control processes. The most sophisticated color measurement process uses a digital spectrophotometer, which measures relative intensities of light in different parts of the color spectrum. The human eye may judge color inaccurately, but spectrophotometers don't lie. The same spectrophotometer reading from one manufacturing plant to another is an excellent assurance of accurate color.
The quality of grout materials also affects color consistency. While site conditions and installations practices always matter, high-performance grouts are formulated to help neutralize some causes of inconsistent color.
Technically advanced grouts contain additives that reduce sensitivity to variables such as temperature and humidity, joint size, tile types and glazing, and amounts of water used for mixing. These same grouts also contain color additives that neutralize color variation caused by cement, and premium pigments that enhance color development.
Premium grouts are also formulated for ease of use. They are easy to mix, have extended pot life and working time, spread easily, and are easy to clean from the tile or stone surfaces. This is important for helping the installer deliver results that meet customers' high expectations.
Color consistency of equal importance
Assuming that the color of the grout materials is accurate, color consistency problems can develop on the work site - as every contractor knows all too well. That's why an understanding of color consistency is equally important as color accuracy.
Color consistency means the customer's installed grout remains the same, uniform color from one side of the room to the other. Common color problems include spots of less or more intense color (mottling), and differences in intensity from one tile joint to the next.
Common factors that affect color consistency are over watering during mixing or cleanup, grout joint size and depth, tile type (absorptive stones or clays versus porcelain), tile overglazing, and grout installation and curing conditions (warm or cool, dry or humid).
Over watering: Cement in grout reacts with water to form the hydrated crystals that deliver strength. Cement needs water in order to set, but too much water during mixing and cleanup can lead to shrinkage cracks or color that is too light. Over watering can also cause efflorescence, in which salts from the grout cement go into solution, then deposit on the grout surface when the water evaporates. The salt deposits make the grout appear lighter or, in extreme cases, appear as crystals on the surface.
Grout joint size: Ideally, the grout joint is twice as deep as it is wide, but conditions are seldom ideal. The biggest contributor to variations in joint depth is mortar that squeezes up into the joint, creating shallow areas. Thinner sections of grout will appear darker - this is a common cause of grout mottling.
Tile types: Tiles differ in their capacity to absorb water from wet grout. Vitreous and porcelain tiles are non-porous and so draw little or no water from the grout as it cures. This tends to result in lighter-colored grout. Conversely, clay-bodied tiles and porous stone materials can absorb large amounts of water and will tend to yield darker-colored grout. A common problem area is a cut edge of a glazed clay tile - a highly absorptive surface that will likely darken the neighboring grout.
Tile overglazing: In the manufacturing process, tiles are glazed as they travel on a conveyor beneath a nozzle that sprays the glazing compound. In the process, glaze may be applied to the leading and trailing edges of the tile. The overglazed edges are less absorbent, and will tend to lighten the neighboring grout.
Curing conditions: Grout curing involves chemical reactions, which of course are affected by temperature and humidity. Low temperatures can delay or even stop cement hydration. High temperatures and low humidity can cause dehydrated and "soft" grout. In either case, color can be affected.
Getting it right
While high-performance grouts make color consistency easier to achieve, installers still need to be vigilant on the job.
Proper mixing is essential. Dry mixing of the contents before mixing with water ensures that cement and pigments are evenly distributed. It is advisable to mix an entire bag of grout at one time. If the grout is mixed in small batches, the amount of water used may vary, and the color of each batch may be slightly different.
The manufacturer's mixing recommendations should be observed. While it may be tempting to use more than the recommended amount of water to make the grout easier to work with, the price may be dilution of the color and an unhappy customer. Of course, clean water for mixing is a must.
Slaking is an important step. During the 10 to 15 minutes required for the ingredients to "wet out," the grout properties improve and the color pigments develop. After slaking, the grout should be remixed to achieve the optimum installation properties and color.
Temperature and humidity affect how quickly the grout cures and dries. Manufacturers' recommendations can vary, but typically grouts should not be applied below 50o F or above 90o F. Steps should be taken when applying in adverse conditions, for example damp curing in dry conditions.
After installation, the grout clean-up procedure should be performed at the right time - neither too soon nor too late. If done too early, there's a risk of disturbing the surface and watering down the grout, potentially altering its color. Performing the cleaning procedure too late, of course, makes cleanup difficult and might require the use of more water, which can also affect the color. A general rule of thumb is to clean up grout haze as soon as possible after the grout has set up in the joint, which is typically 30-60 minutes. In addition, it's important to keep the clean-up materials (e.g., sponge, towel, etc.) as dry as possible.
Manufacturers recommend shelf lives for their products, and they should be observed. This is because, over time, moisture from the atmosphere can enter the container and start the chemical reactions involved in curing. As a result, grout used beyond its shelf life sets up structurally weak.
Keeping customers happy
Quality flooring jobs result from skilled installers using premium-grade materials according to directions and sound work practices. When these factors come together on a project, the results are fewer callbacks and complaints and better-satisfied customers with potential to provide repeat business and referrals.