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Glossary of Terms

Abrasion resistance
The degree to which a floor tile’s surface will withstand friction (the wear of foot traffic). Resistance is determined by abrasion tests. (AS 4459-7) classifies tiles from Group I (suitable for light residential traffic) to Group V (suitable for commercial traffic).

Absorption
The quantity of water a tile can absorb expressed as a percent of the dry tile weight. High water absorption corresponds to a porous structure, while compact, vitrified structures feature low water absorption.

Adhesive
A substance capable of holding materials together by surface attachment. Note: Adhesive is the general term used and includes cement, glue, mucilage, thin-set and paste. All of these terms are loosely used interchangeably. Various descriptive adjectives are applied to the term adhesive to indicate certain characeristics as follows: (a) Physical form,. that is liquid adhesive, tape adhesive, (b) Chemical type, that is, silicate adhesive, resin adhesive, (c) Materials bonded, that is, paper adhesive, metal-plastic adhesive, can label adhesive, (d) Conditions of use, that is, hot-setting adhesive.

Basalt (Bluestone)
A hard blackish coloured volcanic rock composed of fine-grained plagioclase feldspar and ferromagnesian minerals. The term ‘Bluestone’ is often referred to in Victoria, Australia, as ‘basalt’, but elsewhere it has been used to describe other bluish sedimentary rocks such as dense feldspathic sandstones or siltstones.

Bicottura
Literally ‘two firings’, referring to the separate firing of the clay body and the glaze. Bicottura glazes are not as scratch resistant and are now only used on walls.

Body (of tile)
The structural portion of a ceramic article such as the clay material or mixture, as distinct from the glaze.

Bullnose tiles
Tiles featuring a rounded edge used to finish wall installations, turn outside corners or applied to the leading edge for some steps.

Clinker tiles (also Klinker)
Natural clay tile, generally extruded and unglazed, vitrified or impervious to moisture and therefore suitable for indoor and outdoor use.

Cove tiles
Cove trim tiles with rounded top edge, used to finish tile installation as baseboard, backsplash, etc.

Decorated tile
Ceramic tiles that have been embellished by means of hand painting, silk screening, decals or other techniques.

Double Pressed
This is a popular choice because it gives the look of natural stone like marble and granite, but with the strength of a full porcelain tile. They’re so called because two different hues of porcelain are fused together when the tiles are made. Although these tiles don’t have the maintenance of natural stone, they are more expensive.

Dry-pressed tile
Tiles formed by the compaction of finely milled raw materials in moulds before firing. The majority of indoor tiles are produced this way.

Efflorescence
Crystalline deposit that sometimes appears on the surface of grout joints or unglazed tiles as a whitish powder or crust, caused by moisture reacting with impurities in the mortar.

Epoxy
Resin material used in mortars and grouts for thin-set tile installations.

Epoxy Grout
A two part grout system consisting of epoxy resin and epoxy hardener. Made to have impervious qualities, stain and chemical resistant. Used to fill joints between tiles.

Expansion Joint
Separation provided between adjoining parts of a structure to allow movement at stress points to prevent uncontrolled cracking.

Extruded tiles
Tiles formed by the extrusion process wherein the still malleable or plastic raw clay is forced through a mould and then cut into shape before firing.

Finishes
Textural or visual characteristics of a tile surface. For glazed tile this may be high gloss, satin or matt. Generally for porcelain tiles, finish can be natural, polished, semi-polished, honed, lapped. Other finishes mimicking stone such as bush hammered are also available. Other effects include raised, embossed, dimpled, etched, scored, ribbed, etc.

Firing
Final step of tile manufacturing process when raw material is ‘baked’ at high temperature (up to 1250 degrees C for porcelain tiles) to harden the tile body and glaze (if present).

Format
The size of tiles or mosaics may vary from 10mmx10mm to 500x1000mmm. Format is a modern term that simply refers to size.

Frost resistance
Ability of certain ceramic tiles to withstand freeze/thaw conditions with minimal effect. Frost resistance of ceramic tile is dependent on the tile’s porosity and water absorption levels.

Glaze
Glassy opaque or transparent coating fired or fused on to the ceramic tile body, creating a smooth, impermeable surface.

Glazed porcelain
This tile has a porcelain ‘biscuit’, or foundation, over which a ceramic is applied (Glaze), to give the look of, for example, terracotta, but with more durability. Now the most popular type of indoor floor tile. They are dense, strong and best cut with a wet saw.

Glazed through-body porcelain
A glazed through-body tile mixes a pigment into the porcelain so the biscuit looks the same as the glaze. This is to counter one the drawbacks of normal glazed porcelain, is being that the surface glaze has the same weaknesses as a normal ceramic tile – it’s prone to chipping, and when it does, you’ll see the differently coloured porcelain biscuit underneath. With the through-body porcelain, if the glaze chips, it won’t look so unsightly.

Unglazed through-body porcelain
An unglazed through-body tile mixes a pigment into the porcelain so the biscuit looks the same as the glaze. This is to counter one the drawbacks of normal glazed porcelain, is being that the surface glaze has the same weaknesses as a normal ceramic tile – it’s prone to chipping, and when it does, you’ll see the differently colored porcelain biscuit underneath. With the through-body porcelain, if the glaze chips, it won’t look so unsightly.

Granite
A visibly granular, igneous rock ranging in colour from pink to light or dark grey and consisting mostly of quartz or feldspars, accompanied by one or more dark ferromagnesian minerals. Granite, which is denser in appearance than marble, is frequently used as a benchtop material, wall and floor tiles and cladding.

Grout
A rich or strong cementitious or chemically setting mix used for filling tile joints, which can come is a variety of colours.

Grout joint
Space left between tiles to be filled with grout. This space may be extremely narrow or wider depending on the required installation and/or its aesthetics.

Impact resistance
Ability of ceramic tile to resist breakage – either throughout the body or as surface chipping – as the result of a heavy blow. In general, ceramic tile is not a resilient material, and care should be taken to avoid dropping heavy or sharp objects on its surface. Glazed tiles are more susceptible to surface chipping than unglazed tiles.

Inserts
Small, sometimes decorative tiles used in combination with larger or plain tiles to create patterns. Small square inserts are also known as a taco or tozzetto.

Limestone
A rock of sedimentary origin composed principally of calcium carbonate (the mineral calcite), or the double carbonate of calcium and magnesium (the mineral dolomite), or some combination of these two minerals (ASTM CII9). (Recrystallised limestone, compact microcrystalline limestone and travertine that are capable of taking a polish are also included in the category ‘commercial marble’ and may be sold as either limestone or marble.)

Lippage
In finished installations, lippage refers to the condition where one edge of a tile is higher than an adjacent tile. Excessive lippage can cause trips and falls.

Listello
Narrow decorative border tile, often designed to compliment a range of field tiles.

Marble
A true marble is a metamorphosed limestone capable of taking a polish, which exhibits a recrystallised interlocking texture composed principally of the carbonate minerals calcite and/or dolomite. However, some stones in the industry are referred to as green marbles, many of which are composed principally of mineral serpentine and by geological definition, should not be included in the marble definition. (It is important to distinguish between these two types of marbles, since some, but not all, green marbles are dimensionally unstable.) Marble is widely used as a vanity top material and wall and floor tiles.

Modular format
Combining different tile sizes is a popular trend which may be described as ‘modular’. Generally a mixture of sizes from the same tile series are laid together to create a more interesting pattern in the installed tiles.

Mohs’ scale
Scale used to express the measure of a material’s hardness from Mohs’ 1 (hardness of talc) to 10 (diamond).

Monocottura
Tiles produced with only one high temperature firing, generally with harder glaze and denser body than wall tiles with moisture absorption below 3 percent.

Monoporosa
Single-fired tiles with higher porosity and water absorption levels than ‘monocottura’ tiles.

Mosaic tiles
Mosaic tiles are defined by their size, generally less than 15cm square. Their composition can be Marble, Metal, Glass or Ceramic tiles. They may have a variety of finishes (-Tumbled, Polished or Honed for Marble mosaics, -Polished or Brushed for Metal mosaics, -Gloss or Matt for Glass mosaics and Glazed or Unglazed for Ceramic mosaics.

Mud
A slang term referring to thick-bed mortar consisting of sand and cement.

Pencil tiles
Narrow rectangular tiles (e.g. 2x20cm) sometimes with rounded surface, used on walls as accent pieces. These are often referred to as cappings.

Porcelain stoneware
Dust-pressed ceramic tiles with water absorption levels less than 0.5% and high mechanical and chemical characteristics. The surface of these tiles may be glazed or unglazed. Often specified for exterior installations, they are also referred to as fully vitrified.

Porosity
Volume of pores relative to volume of tile body and capable of absorbing moisture (and therefore stains).

Quarry tiles
Traditional term for single extruded natural clay tiles with a water absorption level not exceeding 6%. Can be glazed or unglazed.

Rectified
Cutting or grinding the edges off a tile allows the dimensions and squareness to be precisely controlled. Typically exhibiting a very square edge, rectified tiles are generally suited for installing with minimal grout lines between the tiles.

Sandstone
A sedimentary rock composed mostly of mineral and rock fragments within the sand sized range (from 2 to 0.06 mm) and having a minimum of 60% free silica, cemented or bonded to a greater or lesser degree by various materials including silica, iron oxides, carbonates or clay and which has a compressive strength over 28 MPa (ASTM C119, Quartz-based Dimension Stone Definition II). Australia has vast resources of natural stone; particularly sandstone.

Sealers
Clear coating penetrant applied to protect and prevent the absorption of liquids from spills or staining from other debris. Used with porous materials including: quarry tile, grout, natural stone. (also known as sealants).

Slate
A microcrystalline metamorphic rock most commonly derived from shale and composed mostly of micas, chlorite and quartz. Slate is a popular stone that has many applications.

Slip resistant tiles
Tiles treated to prevent slipping either by adding an abrasive grit to the glaze or a texture to the design of the tile surface structure such as ribs, studs etc.

Slip Resistance Tests
Are tests to show the coefficient of friction (traction) of the surface of tile? These tests are rarely used for stone. The ADA, (Americans with Disabilities Act 1990) recommends an average rating of .6 or better. The average is between a wet test and a dry test.

Spacers
T-shaped and + shaped, they are used in installation to separate tile on walls and floors. They are manufactured in various thicknesses

Terracotta
Traditional clay used to produce unglazed, cream to red body tiles, generally extruded and 12 mm thick or more. Surface may be rustic, smooth, polished, or waxed.

Travertine
Has a similar composition to limestone but with holes created by hot springs. Colours include beige, red, yellow and brown, with some variation from piece to piece. The porous holes can be left unfilled and the surface can be simply honed or they can filled in with either a resin or a cement based fill. The surface of filled travertine can be either Honed or Polished.

Unglazed tiles
Unglazed tiles derive their colour and texture from their raw materials or may be coloured by means of oxides dispersed throughout the body. They are generally fully vitrified.

Vitrified tiles
Vitreous tiles absorb less than 3 percent moisture whereas Fully Vitrified tiles are made from fine particles and fired to high temperatures (1250 degrees) which results in a denser tile with extremely low porosity (moisture absorption of less than 0.5 percent). Porcelain stoneware tiles are fully vitrified making a layer of glaze unnecessary for the tile to be impervious to water.

Wastage
Generally add 10 percent to the amount required for wastage due to cutting etc. If the installation is complicated or a lot of cutting is involved, the amount for wastage may need to be increased to 15 percent.

Water absorption
The quantity of water a tile can absorb expressed as a percent of the dry tile weight. High water absorption corresponds to a porous structure, while compact, vitrified structures feature low water absorption.