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ABRAHMS LAW – A rule stating that with given concrete materials and conditions of test the ratio of the amount of water to the amount of the cement in the mixture determines the strength of the concrete provided the mixture is of a workable consistency.


ABRASION – Wearing away by friction


ABRASION RESISTANCE – The ability of a surface to resist being worn away by rubbing and friction.


ABSORBED MOISTURE – Moisture that has entered a solid material by absorption and has physical properties not substantially different from ordinary water at the same absorption. The relationship of the weight of the water absorbed by a ceramic specimen subjected to pre­scribed immersion procedure, to the weight of the dry specimen, expressed in percent.


ACCELERATOR – A substance which, when added to con­crete, mortar, or grout, increases the rate of hydration of the hydraulic cement, shortens the time of setting, or increases the rate of hardening of strength develop­ment, or both.


ACID – A chemical substance usually corrosive to common metals (iron, aluminum, zinc) and which, in water solution, imparts an acid, sour or tart taste. Acids are generally divided into two classes: (a) strong mineral or inorganic acids such as sulfamic, sulfuric, phosphoric, hydrochloric or nitric, (b) weak organic or natural acids such as acetic (vinegar), citric (citrus fruit juices), oxalic and fatty acids (oleic, palmitic, stearic, etc.)


ACID & ALKALI-RESISTANT GROUT – Is a grout that resists the effect of prolonged contact with acids and alkalis.


ACIDITY – A general term applying to substances on the acid side of neutral – principally the degree of acidity.


ACRYLIC – A general class of resinous polymers derived from esters, amides or other acrylic acid derivatives.


ADDITIVE – A term frequently (but improperly) used as a synonym for addition or admixture.


ADHESIVE – A substance capable of holding materials to­gether by surface attachment. Note: Adhesive is the general term and includes among other cement, glue, mucilage and paste. All of these terms are loosely used interchangeably. Various descriptive adjectives are applied to the term adhesive to indicate certain characteristics 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.


ADMIXTURE – A material other than water, aggregates, and hydraulic cement, used as an ingredient of concrete or mortar, and added to the concrete immediately before or during its mixing.


ADOBE – Unburnt brick dried in the sun.


AGGEREGATE – Granular material, such as sand, gravel, crushed stone, and iron blast-furnace slag, used with a cementing medium to form a hydraulic-cement, con­crete or mortar.


AIR ENTRAINING – The occlusion of air in the form of minute bubbles (generally smaller than lmm) during the mixing of concrete or mortar.


ANDALUSITE – A polymorph, along with sellimanite and kyanite, of composition A1203 Si02. On firing, it dis­sociates to yield principally mullite.


ANGLE DIVIDER – The angle divider is used by the tilesetter to determine the degree of an angle to cut. It is used for fitting trim, moldings, and floors into corners. A corner angle is measured by adjusting the divider to fit the corner.



BASALT WARE – Is a black unglazed vitreous ceramic ware having the appearance of basalt rock.


BASE – One or more rows of tile installed above the floor. See Cove.


BELLEEK CHINA – A highly translucent whiteware composed of a body containing a significant amount of frit and normally having a luster glaze. (Produced commer­cially in Belleek, Ireland.)


BICOTTURA – Is the second firing of the bisque after the glaze or decoration has been applied.


BISCUIT CHIPS – Glazed-over chips on the edge or corner of the body of a tile.


BISCUIT CRACKS – Any fractures in the body of a tile visible both on face and back.


BISQUE – any tile shape ready to be glazed.


BLEB – A small blister or bubble.


BLISTERING – The development during firing of enclosed or broken macroscopic vesicles or bubbles in a body, or in a glaze or other coating.


BLOTS – Green marks or stains on the face of a tile.


BRIGHT GLAZE – colorless or colored ceramic glaze having high gloss.


BROOM FINISH – The surface texture obtained by stroking a broom over freshly placed concrete.


BRUSHED SURFACE – A sandy texture obtained by brushing the surface of freshly placed or slightly hardened con­crete with a stiff brush for architectural effect or, in pavements, to increase skid resistance. You can also achieve a brushed surface on stone by using acid and a brush.


BULLNOSE – A trim tile with a convex radius on one edge. . This tile is used for finishing the edge of ceramics and porcelains, although not all porcelains need bullnose.


BULLNOSE CORNER – A type of bullnose trim with a convex radius on two adjacent edges.


BUTTERING – The spreading of a bond coat (followed by a mortar coat, a thin-setting bed mortar, or an organic adhesive) to the backs of ceramic tile just before the tile is placed.



CEMENT BODY TILES – Tiles with the body made from a mix­ture of sand and Portland cement. The surface may be finished with Portland cement, spheroids of marble or other materials.


CEMENT GROUT – A cementitious mixture of Portland ce­ment, sand or other ingredients and water which pro­duces a water resistant, uniformly colored material used to fill joints between tile units.


CEMENT MORTAR – A cementitious mixture of Portland cement, sand or other ingredients and water which is used for bonding tile to back-up material.


CERAMIC TILE – A ceramic surfacing unit, usually relatively thin in relation to facial area, made from clay or a mix­ture of clay; and other ceramic material, called the body of the tile, having either a “glazed” or “unglazed” face, and fired above red heat in the course of man­ufacture to a temperature sufficiently high to produce specific physical properties.


CERAMIC WHITEWARE – A fired ware consisting of a glazed or unglazed ceramic body which is commonly white and of fine texture. This term designates such products as china, porcelain, semi vitreous ware and earthen­ware.


CHECKING – Short shallow cracks on the surface.


CLAY – A natural mineral aggregate, consisting essentially of hydrous aluminum silicates; it is plastic when suffi­ciently wetted, rigid when dried en masse, and vitri­fied when fired to a sufficiently high temperature.


CLEAR GLAZE – A colorless or colored transparent ceramic glaze.


COLOR – The aspect of the appearance of an object de­pendent upon the spectral composition of the incident light, the spectral reflectance of transmittance of the object, and the spectral response of the observer. Hue – The attribute by which a perceived color is distin­guished as red, yellow, green, blue, purple or a com­bination of these. White, gray and black colors possess no hue. Lightness – The attribute by which a per­ceived color is judged to be equivalent to a member of the continuous series of grays ranging from black to white. Saturation – The attribute by which a per­ceived color is judged to depart from gray of equal lightness toward a pure hue.


COLORED GROUT – Commercially prepared grout consist­ing of carefully graded aggregate, Portland cement, water dispersing agents, plasticizers and color fast pig­ments.


COMPRESSIVE STRENGTH – The measured maximum resist­ance of a concrete or mortar specimen to axial loading; expressed as force per unit cross-sectional area; or the specified resistance used in design calculations, in the U.S. customary units of measure expressed in pounds per square inch (psi).


CONCRETE TERRAZZO – Marble-aggregate concrete that is cast-in-place precast and ground smooth for decorative surfacing purposes on floors and walls.


COVE – A trim tile unit having one edge with a concave radius. A cove is used to form a junction between the bottom wall course and the floor or to form an inside corner. (TCA)


COVE BASE, SANITARY – A trim tile having a concave radius on one edge and a convex radius with a flat landing on the opposite edge. This base often is used as the only course of tile above the floor tile.


CRAWLING – A parting and contraction of the glaze on the surface of ceramic ware during drying or firing, result­ing in unglazed areas bordered by coalesced glaze.


CRAZING – The cracking which occurs in fired glazes or other ceramic coatings due to critical tensile stresses.


CRYSTALLINE GLAZE – Glazed tile with an extra heavy glaze produced for use on counter tops and light duty floor surfaces where abrasion or impact is not excessive. (CTI)


CURING – Maintenance of humidity and temperature of freshly placed concrete during some definite period following placing, casting, or finishing to assure satis­factory hydration of the cementatious materials and proper hardening of the concrete.


CUSHIONED EDGE TILE – Tile on which the facial edges have a distinct curvature that results in a slightly recessed joint.



DECORATION INGLAZE – A ceramic decoration applied on the surface of an unfired glaze and matured with the glaze.


DECORATION OVERGLAZE – A ceramic or metallic decoration applied and fired on the previously glazed surface of ceramic ware.


DECORATION UNDERGLAZE – A ceramic decoration applied directly on the surface of ceramic ware and sub­sequently covered with a transparent glaze.


DELFT WARE – A calcareous earthenware having an opaque white glaze and monochrome over glaze decorations. (Originated in Delft, Holland.)


DOLOMITE – The double carbonate of lime and magnesia having the general formula CaC03 MgCA3


DOUBLE BULLNOSE – A type of trim with the same convex radius on two opposite sides.


DRYING – Removal by evaporation, of uncombined water or other volatile substance from a ceramic raw material or product, usually expedited by low temperature heating.


DRY SPOTS – Small areas on the face of tile which have been insufficiently glazed.



EARTHENWARE – A glazed or unglazed non-vitreous ceramic white ware.


EFFLORESCENCE – The residue deposited on the surface of a material by the crystallization of soluble salts.


EGGSHELLING – The texture of a fired glaze similar in appearance to the surface of an eggshell.


EMBOSSED – A decoration in relief or excised on the ware surface.


ENGOBE – A slip coating applied to a ceramic body for im­parting color, opacity or other characteristics, and sub­sequently covered with a glaze.


EPOXY ADHESIVE – A two-part adhesive system employing epoxy resin and epoxy hardener used for bonding of ceramic tile to back-up materials.


EPOXY GROUT – A two-part grout system consisting of epoxy resin and epoxy hardener, especially formu­lated to have impervious qualities, stain, and chem­ical resistance, used to fill joints between tile units.


EPOXY MORTAR – A two-part mortar system consisting of epoxy resin and epoxy hardener used to bond tile to back-up material where chemical resistance of high bond strength is a consideration.


EXTRUDED TILE – A tile or trim unit that is formed when plastic clay mixtures are forced through a pug mill opening (die) of suitable configuration, resulting in a continuous ribbon of formed clay. A wire cutter or similar cut-off device is then used to cut the ribbon into appropriate lengths and widths of tile.


FAIENCE TILE – A glazed or unglazed tile, generally made by the plastic process, showing characteristic varia­tions in the face, edges, and glaze that give a hand­crafted, non mechanical, decorative effect.


FAN OR FANNING – Spacing tile joints to widen certain areas so they will conform to a section that is not parallel.

FEATURE STIP – A narrow strip of tile that has a contrasting color, texture, or design.

FELDSPAR – A mineral aggregate consisting chiefly of microcline, albite and/or anorthite. Also know as a listelle.


FLASH POINT – The temperature at which the material gives off flammable vapor in sufficient quantity to ignite momentarily on the application of a flame under specified conditions.


FRIT – A glass which contains fluxing material and is employed as a constituent in a glaze, body or other ceramic composition.


FRITTED GLAZE – A glaze in which a part or all of the fluxing constituents are prefused.


FROST PROOF TILE – Tile produced for use where freezing and thawing conditions occur.



GLASS MOSAIC TILES – Tiles made of glass, usually in sizes not over two (2) inches square and 1/4 inch thick, mounted on sheets of paper. Usually sheets are twelve (12) inches square.


GLAZE – A ceramic coating matured to the glassy state on a formed ceramic article. The term glaze also refers to the material or mixture from which the coating is made.


Bright glaze – A high-gloss coating with or without color.

Clear glaze – A transparent glaze with or without color.

Crystalline glaze – A glaze that contains microscopic crystals.

Fritted glaze – A glaze in which a part or all of the fluxing constituents are pre-fused.

Matte glaze – A low-gloss ceramic glaze with or without color.

Opaque glaze – A nontransparent glaze with or with­out color.

Raw glaze – A glaze compounded primarily from raw constituents. It contains no pre-fused materials.

Semi matte glaze – A medium-gloss ceramic glaze with or without color.

Speckled glaze – A glaze containing granules of oxides or ceramic stains that are of contrasting colors.


GAUGED OR GAUGING – A grinding process to make all pieces of material to be used together with the same thickness.


GAZED INTERIOR TILE – A glazed tile with a body that is suitable for interior use and which is usually non­vitreous, and is not required or expected to withstand excessive impact or be subject to freezing and thaw­ing conditions.


GLOSS FIRING – is a second firing at a lower temperature which fuses the glaze with the bisque


GRADE – A predetermined degree of slope that a finished floor should have.


GROUT – A rich or strong cementitious or chemical set­ting mix used for filling tile joints.



IMPERVIOUS – That degree of vitrification evidenced visually by complete resistance to dye penetration.

NOTE: The term impervious generally signifies zero absorp­tion, except for floor and wall tile which are considered “impervious” up to 0.5% water absorption. Impervious tile has water absorption of 0.5 percent or less.



LIMESTONE – A sedimentary carbonate rock, composed chiefly of calcite (Ca C03), but sometimes containing appreciable dolomite.


LOAD BEARING WALL – A wall designed and built to carry superimposed vertical and shear loads as opposed to non-load bearing walls.



MAJOLICA – Formerly an earthenware with an opaque luster glaze and overglaze colored decorations, but currently designating any decorated earthenware having an opaque glaze.


MASTIC GROUT – A chemical mixture of organic and in­organic ingredients forming a one part grouting composition that is used directly from the manu­facturer’s container.


MATTE GLAZE –  A colorless or colored ceramic glaze having low gloss.


MATURING RANGE – The time-temperature range within which a ceramic body, glaze, or other composition may be fired to yield specified properties.


MEXICAN PAVER TILE – A handmade Terra cotta-like tile, used mainly for floors. These tiles vary in color, texture and appearance, from tile to tile and within each tile. They are available in squares up to 12 inches, hexagon, octagon, elongated hexagon, fleur de lis and other shapes. These tiles are coated with various types of sealers because of their soft absorp­tive characteristics. The coatings provide a wearing surface on the pavers which would otherwise powder away under wear.


MODULUS OF ELASTICITY – The ratio of normal stress to corresponding strain for tensile or compressive stresses below the proportional limit of the material; referred to as “elastic modulus of elasticity”; “Young’s mod­ulus,” and “Young’s modulus of elasticity”; denoted by the symbol E.


MODULUS OF RUPTURE – A measure of the ultimate load ­carrying capacity of a beam and sometimes referred to as “rupture modulus” or “rupture strength”. It is calcu­lated for apparent tensile stress in the extreme fiber of a transverse test specimen under the load which pro­duces rupture.


MOLD – 1) A divider containing a cavity into which neat cement, mortar, or concrete test specimens are cast; 2) A form used in the fabrication of precast mortar or concrete units (e.g., masonry units).


MOLD OIL – A mineral oil that is applied to the interior sur­face of a clean mold, before casting concrete or mortar therein, to facilitate removal of the mold after the con­crete or mortar has hardened.


MONOCUTTURA – (Single-Fired). A term used for tile man­ufactured by a process which allows the simultaneous firing of the clay with the glaze producing a finished tile with a single firing.


MOSAICS – the body is generally 1/4″ to 3/8″ thick with a facial area of less than six square inches. It is usually offered mounted, on one foot by one foot sheets.


MORTAR – A mixture of cement paste and fine aggregate; in fresh concrete, the material occupying the inter­stices among particles of coarse aggregate; in masonry construction, mortar may contain masonry cement, or may contain hydraulic cement with lime (and possibly other admixtures) to afford greater plasticity and work­ability than are attainable with standard hydraulic cement mortar.


MOUNTED TILE – Tile assembled into units or sheets by suitable material to facilitate handling and installa­tion. Tile may be face-mounted, back-mounted or edge-mounted. Face-mounted tile assemblies may have paper or other suitable material applied to the face of each tile, usually by water soluble adhesives so that it can be easily removed after installation but prior to grouting of the joints. Back-mounted tile assemblies may have perforated paper, fiber mesh, resin or other suitable material bonded to the back and/or edges of each tile which becomes an integral part of the tile installation. Back-mounted and edge mounted tile assemblies shall have a sufficient ex­posure of tile and joints surrounding each tile to comply with bond strength requirements. Tile manu­facturers must specify whether back-mounted and edge-mounted tile assemblies are suitable for instal­lation in swimming pools, on exteriors and/or in wet areas.


MUD – A slang term for mortar.


MURALS – Tile installed in a precise area of a wall or floor to provide a decorative design or picture. Glass or marble mosaic tile (tesserae) made to form a picture or design. Ceramic tile painted and fired to form a picture or design.



NATURAL CLAY TILE – A tile made by either the dust-pressed method or the plastic method, from clays that pro­duce a dense body having a distinctive, slightly tex­tured appearance.


NOMINAL SIZES – This is the approximate facial size or thickness of tile, expressed in inches or fractions of an inch, for general reference.


NON-SLIP TILE – Tile having greater non-slip character­istics due to an abrasive admixture, abrasive particles in the surface, grooves or patterns in the surface or because of natural non-skid surface characteristics.



OPAQUE GLAZE – A nontransparent colored or colorless glaze.


NONVITREOUS – (nonvitrified) That degree of vitrification evidenced by relatively high water absorption.            Note:  The term nonvitreous generally signifies more than 10.0 % water absorption, except for floor         and wall tile which are considered nonvitreous when water absorption exceeds 7 %.



PACKING HOUSE TILE – Similar to quarry tile, but usually of greater thickness.


PAVERS – Unglazed porcelain or natural clay tile formed by the dust-press method and similar to ceramic mosaics in composition and physical properties but relatively thicker with 6 in.- or more of facial area.


PINHOLES – Imperfections in the surface of a ceramic body or glaze resembling pin pricks.


PITTED – Indentations in the finished surface of individual tiles other than at the corners and edges. These are caused by sharp corners on trowels and other tools of the workmen and are different than manu­facturing defects.


PLUMB – Perpendicular to a true level.


POROSITY, APPARENT – The relationship of the open pore space to bulk volume, expressed in a percent.


PORCELAIN – A glazed or unglazed vitreous ceramic white­ware used for technical purposes.


PRESSING, DRY – Forming ceramic ware in dies from powdered or granular material by direct pressure.


PRESSING, HOT – A jiggering process wherein a heated profile tool or plunger is employed.


PRESSING, WET – (plastic pressing). Forming ceramic ware in dies from a plastic body by direct pressure.


PROCESS, DRY – (dry mix). The method of preparation of a ceramic body wherein the constituents are blended dry, following which liquid may be added as re­quired for subsequent processing.


PROCESS, WET – (slip process). The method of preparation of a ceramic body wherein the constituents are blended in sufficient liquid to produce a fluid sus­pension for use as such or for subsequent processing.


P.S.I. – Pounds per square inch, a unit measure of pressure.



QUARRY TILE – Unglazed tile, usually 6 in.  or more in sur­face area and ‘/z to 3/4 in. (13 to 19 mm) in thickness, made by the extrusion process from natural clay or shales.



RAW GLAZE – A glaze compounded primarily from raw constituents, that is, containing no pre-fused ma­terials.


REDUCER – A trim unit used to reduce the radius of a bullnose or a cove to another radius or to a square.


RELATIVE HUMIDITY – The ratio of the quantity of water vapor actually present to amount present in a saturated atmosphere at a given temperature; expressed as a percentage.


RETURN – The ending of a small splash wall or a wain­scot at right angle to the major wall.


RUBBER SPACERS – Cross and tee-shaped objects used to space tile on floors or walls. They are manufactured in thicknesses of 1/16″, 1/8″, 1/4″, 3/8″, and 1/2″.



SALT GLAZE – A glaze produced by the reaction, at elevated temperature, between the ceramic body surface and salt fumes produced in the kiln atmosphere.


SANDBLASTING – A method of scarifying the surface of concrete or masonry to provide a bondable surface, also used to give surface and structure to stone.


SAW CUT – A cut in a hard surface utilizing diamond or silicone-carbide blades or discs.


SECOND GRADE CERAMIC TILE – Ceramic tile with appear­ance defects not affecting wearing or sanitary qualities.


SEMI-MATTE GLAZE – A colorless or colored glaze having moderate gloss.


SEMIVITREOUS – (Semivitrified) The degree of vitrification evidenced by a moderate or intermediate water absorption.  Note:  The term semivitreous generally signifies 0.5 to 10 % water absorption, except for floor and wall tile which are considered semivitreous when water absorption is between 3.0 to 7.0 percent.


SET – The condition reached by a cement paste, mortar, or concrete when it has lost plasticity to an arbitrary degree, usually measured in terms of resistance to penetration or deformation; initial set refers to first stiffening; final set refers to attainment of significant rigidity; also, strain remaining after removal of stress.


SHADE – The gradation of color that often uses a rating scale from V1 to V5.


SHOWER PAN – Terminology used in sonic areas for Wa­terproof membrane.


SKID RESISTANCE – A measure of the frictional characteris­tics of a surface.


SLIP-RESISTANCE TILE – Tile having greater slip-resistant characteristics due to an abrasive admixture, abra­sive particles in the surface or grooves or patterns in the surface.


SOAPING TILE – The method of applying a soapy film to newly tiled walls to protect them from paint and plaster during construction.


SPACERS – T-shaped and Y-shaped, they are used in instal­lation to separate tile on walls and floors. They are manufactured in various thicknesses from 1/16″ to ½”.


STONEWARE – A vitreous or semi-vitreous ceramic ware of fine texture, made primarily from non-refractory fire clay.


STRAIGHT JOINT – The usual style of laying tile where all the joints are in alignment.



TENSILE STRENGTH – The pulling force necessary to break a given specimen divided by the cross sectional area. Units given in lbsdin2 (P.S.I.). It measures the resist­ance of a material to stretching without rupture. Nor­mally is not used with reference to elastic materials which recover after elongation.


TERRA COTTA – Hard baked clayware, including tile, of variable color, averaging; reddish red-yellow in hue and of high saturation.


TERRAZZO TILE – A terrazzo surface, on a Portland cement and sand body, made by a mixture of marble chips and Portland cement and usually ground smooth.


THIN-SET – A term used to describe the bonding of tile with suitable materials applied approximately 1/8″‘ thick.


TILE – A ceramic surfacing unit, made from clay or a mixture of clay and other ceramic materials, fired above red heat to a temperature sufficiently high to produce specific physical properties and characteristics.



UNGLAZED TILE – has a ceramic body that does not have a coating on the surface. Unglazed tile is generally a hard, dense tile of uniform composition throughout, deriving color and texture from the materials of which the tile is made.



VITREOUS TILE – Has water absorption of more than 0.5 %, but no more than 3%.



WALL TILE – A glazed tile with a body that is suitable for in­terior use and which is usually non-vitreous, and is not required nor expected to withstand excessive impact or foot traffic.


WET AREA – These are areas that are either soaked, saturated, or subject to moisture. Examples are tubs, showers, laundries, saunas, steam rooms, swimming pools, etc..