Ceramic/Porcelain Glossary

For definitions of other terms not listed here, please go to these sections: How Ceramic Is Made, Ceramic Styles and Before You Buy Ceramic.

ASTM Most manufacturers will have a rating system that is based on or supported by the American Society for Testing & Materials (ASTM). Many times you can find these ratings on the tile sample or in the product catalog. The most common system rates ceramic tile abrasion resistance or the overall durability of the tile. Other ratings might include: scratch resistance, moisture absorption, chemical resistance and breaking strength.

Biocuttura Tile Ceramic tiles are fired in a kiln at temperatures around 2000 degrees Fahrenheit. Biocuttura Tiles are first fired after the green tile is dried and then fired again after the glaze is applied. Also call Double Fired.

Bisque When you look at a glazed tile from the side you can see 2 layers. The body of the tile, or largest layer, is called the bisque. The top layer is called the glaze.

Bullnose A ceramic floor tile trim that has one rounded finished edge on the tile to give a nice finishing touch. Sometimes it is also used as a substitute for cove base.

Ceramic Ceramic tiles are created from natural products extracted from the earth that are shaped into tiles and then fired in kilns at extremely high temperatures.

CBU Today, many tile ceramic tile installers have opted for the industry accepted and more efficient thin set method, where the tile is adhered directly onto a backer board that is nailed to a plywood or concrete substrate using a much thinner layer of mortar. This backer board is called a CBU, or cement backer unit, which provides a supportive and water resistant layer between the porous substrate and the mortar and tile applied on top of it.

Classes 1-5
Class 1: no foot traffic. These tiles are suggested for interior wall applications only and not for the floor.
Class 2: light traffic. These tiles are suggested for interior wall applications and for residential bathroom flooring only.
Class 3: light to moderate traffic. These tiles can be used for residential floor and wall applications including bathrooms, kitchens, foyers, dining rooms and family rooms. They’re a good all-around performer.
Class 4: moderate to heavy traffic. These tiles are recommended for residential, medium commercial and light industrial floor and wall applications including shopping malls, offices, restaurant dining rooms, showrooms and hallways.
Class 5: heavy/extra heavy traffic. These tiles can be installed anywhere. They will hold up in floor and wall applications at airports, supermarkets and subways.

COF Most manufacturers will have a rating system that is based on or supported by the American Society for Testing & Materials (ASTM). Many times you can find these ratings on the tile sample or in the product catalog. One rating system measures Slip Resistance, which is measured by its Coefficient of Friction (COF). The higher the COF the more slip resistant the tile. This is important when selecting a floor tile for areas that get wet, such as your shower or bathroom floor. Other ratings listed by the manufacturer might include: scratch resistance, moisture absorption, chemical resistance and breaking strength.

Corner Bullnose A ceramic floor tile trim that has two rounded finished edges on the tile to be used to complete a corner.

Extrusion Extruded tiles are formed by forcing the clay material through a mold for the desired shape versus pressing the tile.

Field Tile When creating a pattern with different ceramic tiles, the more prominent tile that is throughout the largest areas is called the “field tile”.

Firing The fifth step in the manufacturing of ceramic tile. The tiles are fired in the kiln at temperatures around 2000 degrees Fahrenheit.

Frit Part of the fourth step (glazing) in the manufacturing of ceramic tile. The glaze liquid is prepared from a glass derivative called frit and colored dyes. The glaze is applied by either a high-pressure spray or is poured directly onto the tile.

Glazed Glazed ceramic tiles are coated with glass-forming minerals and ceramic stains. Typically, they have a matte, semi-gloss or high-gloss finish. They can offer better stain and moisture resistance than unglazed tile. When you look at a glazed tile from the side you can see 2 layers. The body of the tile, or largest layer, is called the bisque. The top layer is called the glaze. Glazed tiles have a hard non-porous, impermeable surface after firing.

Glazing The fourth step in the manufacturing of ceramic tiles. Glazing liquid is prepared from a glass derivative called frit and colored dyes. The glaze is applied by either a high-pressure spray or is poured directly onto the tile.

Green Tiles The third step in the manufacturing of ceramic tile. Here, clay is pressed or formed into a tile shape. These pressed tiles are called green tiles at this stage.

Grout Grout is a type of cement that is used to fill the space and provide support in tile joints. There are two types of grout commonly used in home installations; Portland cement based, and epoxy based. Both of these grout compounds may have sand added to provide additional strength to the tile joint. Pigment is added to the cement at the job site when the grout is mixed.

Impervious Tiles Tiles that have less than .5% moisture absorption. These tiles are frost proof and can be used in exterior areas or on the outside of building facades. You can use these where winter is for real.

Moisture Absorption As the density of the tile increases, the amount of moisture that tile can absorb becomes less. Tile density means that, as the weight or the density of the tile increases, it becomes a stronger tile. Tile density and moisture absorption have an indirect relationship to each other. What this means is that as the density of the tile increases the moisture absorption rate becomes less. Tile density and moisture absorption is important for you to understand when selecting tile for different applications.

Monocuttura Tile Ceramic tiles are fired in a kiln at temperatures around 2000 degrees Fahrenheit. Tiles that are fired once after the glaze is applied are called Monocuttura Tile or single fired.

Mosaics In addition to ceramic tile styles, manufacturers also offer decorative inserts, medallions and mosaics that are used to create intricate patterns and beautiful borders. Tile size 2”x2” and smaller are usually referred to as mosaics and are often used with different colors to create a pattern or decorative inset. Some of these smaller tiles also come in different shapes, such as hexagon.

Nominal Size Tile is usually referred to by its nominal size, not its actual size. During the firing process, ceramic tile will shrink, on average, by about 10% in size. For example a 12” by 12” floor tile will actually measure 11-7/8 inches square. Currently, the most popular ceramic floor tile are the larger sized tiles such as 13” by 13”, 16” by 16” and 18” by 18” sizes.

Non-Vitreous Tiles Tiles that absorb 7% or more moisture. They are suited for indoor use only.

Porcelain Porcelain tile is made up of 50% feldspar and is fired at a much higher temperature than regular ceramic tile. This makes porcelain tile much harder and more dense than other tile products. Because of its highly durable make-up, porcelain is more resistant to scratches and can withstand temperature extremes. Also, because porcelain is non-porous, it’s very stain resistant, has very low water absorption ratings (Less than 0.5%) and thus can be used for interior and exterior applications as well as heavy-use and commercial areas. Finally, because porcelain’s color goes all the way through, small scratches or chips are less noticeable.

Pressing The third and most common step in the manufacturing of ceramic tile. The clay is pressed or formed into a tile shape. These pressed tiles are called green tiles at this stage.

Sanded Grout There are two types of grout commonly used in home installations; Portland cement based, and epoxy based. Both of these grout compounds may have sand added to provide additional strength to the tile joint. Sanded grout is recommended for tile joints 1/8th of an inch and larger.

Sanitary Cove Base A ceramic floor tile trim that has a rounded finished top like a bullnose to cover up the body of the tile.

Semi-Vitreous Tiles Tiles that absorb from 3% to 7% moisture. They are applicable for indoor use only.

Shade Variation Shade variation is inherent in all fired ceramic products and certain tiles will show greater variation within their dye lots. Shade variation is usually listed on the back label of each sample with a low, moderate, high or random rating.
Low: consistent shade and texture.
Moderate: moderate shade and texture variation.
High: high shade and texture variation.
Random: very high shade and texture variation.

Substrate The process for installing a ceramic floor begins with the preparation of the tile foundation, or what’s called the substrate. Common materials used as tile substrates in home installations include concrete, plywood, and drywall.

Thickset/Mud Set In the past, ceramic tile was installed using what is called the thickset or mud set method. In this method, a thick layer of mortar was applied to a waterproofed and steel reinforced substrate. This provided a strong, flat base onto which the tile was installed. The thickset method is effective, but it’s an involved and labor-intensive process.

Thinset Today, many tile installers have opted for the industry accepted and more efficient thinset method, where the tile is adhered directly onto a backer board that is nailed to a plywood or concrete substrate using a much thinner layer of mortar.

Through Body Unglazed tiles that are a solid color all the way through and do not have a top layer of glaze are often referred to as through-body construction. (See Unglazed.)

Tile Density Tile density means that, as the weight or the density of the tile increases, it becomes a stronger tile. Moisture absorption means that, as the density of the tile increases, the amount of moisture that tile can absorb becomes less. Tile density and moisture absorption have an indirect relationship to each other. What this means is that as the density of the tile increases the moisture absorption rate becomes less. Tile density and moisture absorption is important for you to understand when selecting tile for different applications.

Unglazed Unglazed tiles are a solid color all the way through and do not have a top layer of glaze. This is often referred to as through-body construction. They have no additional surface applications and are typically more dense and durable than glazed tile. Thus they are more suitable for interior and exterior applications. Unglazed tiles do have good slip resistance, however please note that they do require sealing to help prevent staining. They come in various surface treatments and textures.

Unsanded Grout There are two types of grout commonly used in home installations; Portland cement based, and epoxy based. Both of these grout compounds may have sand added to provide additional strength to the tile joint. Unsanded grout is typically used in joints that are smaller than 1/8th of an inch.

Vitreous Tiles Tiles that absorb less that 3% moisture. They are referred to as frost resistant tiles but cannot be used in exterior areas where freeze- thaw conditions could cause tile cracking.