Ceramic tile has been used for centuries and offers consumers more options in color, texture, pattern and overall beauty than most other floor covering materials. With new manufacturing techniques today’s ceramic tile designs are virtually indistinguishable from natural marbles, travertines, slates and other stone products.

Today, ceramic tile is manufactured not only in Italy and Spain, but also in Mexico, China, the United States, and many other countries around the world.

The Definition of Ceramic Tile

A thin surfacing unit made from clay and/or a mixture of clay and other ceramic materials; the tile has either a glazed or unglazed face; it is fired above a red heat in the course of manufacture to a temperature sufficiently high to produce specific physical properties and characteristics.

Ceramic tile is simply a mixture of clays which have been shaped and fired at high temperatures, resulting in a hard body.

How Ceramic Tile is Made

The fundamental steps used in the process of manufacturing ceramic tiles have not changed in thousands of years. Mixing, molding, glazing and firing have always been the essential steps required in production. The major changes that have taken place in the ceramic tile industry are the automation of the modern factories.

Today’s highly sophisticated factories, utilizing the latest state-of-the-art technology, mass produce tiles at speeds unimaginable to their forefathers. The ability to mass produce high quality tiles, while at the same time maintaining each tile’s individual characteristics, has given the producers the ability to offer the individual homeowner a product that was once reserved for only kings and sultans.

Ceramic Tiles Composition

All of the raw materials that go into making ceramics come from the earth, including the colors of the glaze. This is a testimonial to the quality of the product. While man has been successful in finding ways to improve most products by substituting natural materials with synthetics, such as in carpet, he has not been able to improve on the quality of raw materials found in ceramics. They have basically remained unchanged for thousand of years.

Glazed ceramic tile is made up of two parts: the body, which is called the BISQUE, and the surface, which is called the GLAZE. The ingredients used to make both the bisque and the glaze are all natural materials mined from the earth. The main ingredient is clay. Types of materials will vary from producer to producer, but could include such elements as quartz, kaolin, fritz, dolomite, cobalt, selenium, and talc.


P.E.I. Wear Rating System – To help select suitable tiles for specific applications tiles are rated the P.E.I. (Porcelain Enamel Institute) scale. The tiles are evaluated for wear resistance on a scale from 1 (lowest) to 5 (highest).

P.E.I. Wear Ratings:

P.E.I. 1 – Tiles suitable only for residential bathrooms where softer footwear is worn.

P.E.I. 2- Tiles suited general residential traffic, except kitchens, entrance halls, and other areas subjected to continuous heavy use.

P.E.I. 3 - Tiles suited for all residential and light commercial interiors such as offices, reception areas and boutiques.

P.E.I. 4 - Suited for all residential interiors and moderate traffic commercial applications.

P.E.I. 5 -Group V Recommended for all interior residential and commercial uses.

MOH’s Rating Scale (Method of Hardness):

The relative hardness of glazed tile is an important issue that should be addressed when selecting a tile. The test is performed by, scratching the surface of the tile with different minerals and subjectively assigning a “MOH’s” number to the glazed.

The softest mineral used is talc (a # 1 rating if no scratch), the hardest is a diamond (a # 10 rating if no scratch). Other minerals that provide MOH’s values of five or greater are suitable for most residential floor applications; a value of seven or greater is normally recommended for commercial applications. Both abrasion resistance and glaze hardness should be addressed when considering using glazed tiles as floor products.

Break Strength – Ceramic tile used on floors and walls must be able to withstand the expected load bearing capacity of various installations. In order to determine the strength and durability of the tile, a standard test method is used to evaluate individual pieces. A force is applied to an unsupported portion of the tile specimen until the breakage occurs. The ultimate breaking strength is then recorded in pounds per square inch. Final selection of the tile should be based upon the breaking strength and the appropriate installation method.

Coefficient of Friction – Tiles used on commercial and residential floors should provide a safe walking surface in wet and dry conditions. By measuring the coefficient of friction, a quantitative number can be determined. To determine this, a 50 pound weight is placed on a neolite heel and is pulled across the surface both wet and dry. The maximum amount of force (pounds) needed to initiate the weight is then recorded. This measurement is divided by the amount of weight (50lbs.) and referred to as the

static coefficient of friction value. A rating of 0.5 is currently recommended by OSHA. The American Disabilities Act recommends a static coefficient of friction value of 0.60 for accessible commercial areas and 0.80 for ramps.

Facts About Glazed Tile

The glaze is a liquid that has been sprayed or pored onto the surface of the tile. It is then fused and hardened by the means of tremendous heat.

The colors of the glaze are made from a mixture of minerals such as gold, silver, zinc, copper, mercury, cobalt, and many others.

The strength and wear resistance of the glaze are determined by its hardness. The following factors affect the hardness:

Temperature – The higher the kilns (oven’s) temperature, the harder the glaze.

Color – Dark color glazes, such as blacks and blues, are usually softer than lighter colored ones.

Gloss Levels – Shiny glazes are usually softer than matte or satin finished glazes.

Facts About the Clay Body (BISQUE)

The clay body, which is also called the bisque, is made up of various types of clay and other minerals. Combined, these raw materials give the bisque its strength and stability.

The strength of the bisque is also determined by its density. The strongest bisques, those suited for heavy commercial installations, have the smallest and fewest number of air pockets. The density of the clay also determines whether the tile is suitable for outdoor use. Tiles that are too porous, absorbing more than

3% moisture, will freeze and crack if installed outdoors in cold climates.

The density of the tile is measure by the amount of water it absorbs. There are four types:

Non-Vitreous tiles absorb 7% or more of their weight in water and more and are suited for indoor use only.

Semi-Vitreous tiles absorb between 3% & 7% of their weight in water and are suited for indoor use only.

Vitreous tile absorb between 0.5% & 3% water and are suited for both interior and exterior use because they are frost resistant.

Impervious tiles, the strongest, absorb between 0% & 0.5% of their weight in water and are suited for both interior and exterior use because they are frost resistant.


Glazed tiles -. Glazed Ceramic Tile is comprised of two basic elements, clay and water. Various clays are mined, ground and blended to a fine powder, and pressed together to form the body of the tile. The pressed clay body is then dried to reduce the moisture content. Next, the surface of the tile is coated with a colored glaze. The glaze is then permanently fused to the surface of the tile by firing it in kilns at approximately 2000° Fahrenheit, to form the finished product.

Unglazed tiles are true inlaids. They are simply baked pieces of clay whose colors run throughout the body of the tile.

Features of Glazed and Unglazed Tiles:

Glazed Tiles – Many glazed tiles are not recommended for heavy commercial installations. They are generally suited for residential and light commercial use, although there are some exceptions. Technology for glazes has improved dramatically over the past few years. Thre are some new glazes on the market that are hard enough and durable enough for use in heavy commercial applications.

Advantages of Glazed Tiles:

The glaze offers the manufacturers the ability to produce an unlimited array of beautiful colors and designs.

The non-porous glaze creates a smooth surface that is virtually stain proof.

Unglazed Tiles – This type of tile is the work horse of the industry. They are generally thicker and denser than glazed tiles. They include such products as quarry tiles and porcelains. Generally, the color range of unglazed tiles is limited to the natural colors of the clay, ranging from light sand to red brick, but there are exceptions. Some manufacturers achieve a wide range of colors by mixing pigments in with the clay.

Two advantages of Unglazed Tiles

Advantages of Unglazed Tiles -Unglazed tiles possess superior strength for heavy-duty commercial and residential use. The rugged surface texture and matte finish of the unglazed tiles give them excellent “slip resistant” qualities for use in wet areas.

Description of Various Popular Tiles

Quarry Tile -Quarry tiles are unglazed tiles made from natural clays and shale. Their colors are usually limited to earth tones, ranging from red to light tan, although some manufacturers add pigments to the clay to offer a wider range of colors. Their body is both thick and dense, making them a popular choice for both heavy commercial and residential installations. Their surface generally has good slip resistant qualities.

Porcelain Tile is made from a blend of fine-grain clays and other minerals to produce a very dense body, which makes it highly resistant to moisture, staining and wear. Because of these features, porcelain tile will withstand years of heavy foot traffic in both interior and exterior applications while maintaining its color and beauty. They come in a wide range of colors which are achieved by mixing pigments with the clay. The special clays allow the product to be fired at extreme temperatures (2,500 degrees F) resulting in a denser and harder body than most other tiles.

Terra-cotta Tiles

Terra-cotta tiles are either handmade or machine made pavers. The machine made terra-cottas are much denser than the handmade tiles and can usually be installed outdoors as they are frost resistant. The most popular handmade tile is Saltio tile from Mexico. Saltio tiles are crudely made, varying widely in size, shade, and texture from one to another. Occasionally, they will even come with animal tracks on the surface. These handmade tiles are very porous and must be waxed to prevent staining and wear. The colors range from terra-cotta to yellow to brown. Additional colors can also be achieved by using stains.

Mosaic Tiles

Mosaic tiles are small tiles, less than 6 square inches in size. They come mounted on perforated paper sheets for easy installations. They are usually very dense products that are tough and stain resistant. Mosaics are ideal for shower floors because their small size gives them the flexibility to follow the contour of the floor as it slopes to the drain. The numerous grout joints also aid in slip resistance. The toughness and stain resistance also make them ideal for countertops. Note: While most quarry, porcelain, terracotta

and mosaic tiles are unglazed, all of them can be produced with a glaze.

Floor and Wall Tiles

Wall Tile - Ceramic wall tiles are normally less durable than tile designed specifically for flooring. Most wall tile is glazed with a semi-gloss or matte surface. The glazed surface has a very low slip resistance and becomes slippery when wet. Therefore, glazed wall tile is much more suited for wall or countertop applications rather than floors.

Floor Tiles

These tiles, glazed or unglazed, have the sufficient strength, impact, and abrasion resistance to withstand weight and foot traffic. They are usually thicker, denser, and heavier than wall tiles. If the substrate is strong enough to support the weight, floor tiles may also be used on walls and counter tops.

Floor tiles range in size from less than one square inch with mosaics up to 24″ x 24″. Although the most popular sizes in the United States for floor tile are still 13″ x 13″ and 12″ x 12″, there is a growing trend towards large tiles. The most popular wall tiles are still 4 ” x 4_” and 6″ x 6″, but here again, there is a trend toward larger tiles such as 8″ x x 810″ and 8″ x 12″.


While square tiles still dominate the market, there are many other shapes available. The include rectangles, hexagons, elongated hexagons, octagons, and many more. Tiles also come in various shaped edges such as straight edges, scalloped edges, and cushioned edges that are heavily beveled to simulate handmade Mexican tile.


Ceramic tile is also available in various surface finishes that include smooth surfaces, textured surfaces that simulate slate, stone, undulated surfaces that imitate handmade tiles, and gritty surfaces for slip resistance.

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