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Ceramic tiles · Commercial and technical classifications Manufactoring Process and Technical Classifications

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MANUFACTURING PROCESS AND TECHNICAL CLASSIFICATIONS

In the past, ceramic tiles were made by manual processes based on working clay and water, and controlling the fire. These processes included:

• selecting, crushing, and mixing natural clays, • preparation, with water, of (clay) pastes for forming or moulding the body in

the plastic state, • forming operation using primitive wood moulds that provided the green piece

with its dimensions, • natural drying to remove most of the water that had been supplied in body

preparation, • a first firing that provided the product with mechanical strength, its definitive

geometry, and surface colour; in some cases, these ceramic tiles were used as covering materials, without any further treatment,

• application of engobes and glazes onto the fired product to mask the colour of the ceramic body, give the fair face a different colour, or make a porous product impermeable,

• application of decorations and other surface treatments, either directly onto the ceramic body or biscuit, or onto the engobes or glazes,

• a further firing process in which the ceramic tile was fired again to provide all its parts with their final state, maturing all elements applied onto the surface of the body or biscuit.

Those traditional tiles were customarily installed with lime mortars, which

provided good adhesion and were slightly deformable, allowing the ceramic tiling to adapt to thermal changes or small movements that occurred in the substrate or in the installed tiles. When not exposed to the action of water, wall and floor tilings installed with lime mortar have resisted the passage of the time until the present day, sometimes in a very good state of conservation.

Since the mid 19th century, a series of changes have taken place in tile processing, which have laid the groundwork for current ceramic technology and for the ceramic families that today’s ceramic industry markets.

THE CURRENT MANUFACTURING PROCESS

The foregoing point has very briefly described the ceramic tile processing steps up to the mid 20th century. These steps include three essential stages for the fabrication of ceramic tile with given characteristics: raw materials selection and treatment, the forming process, and firing. These three stages have undergone numerous innovations and upgradings, which have led to current ceramic technology, in terms of the processes illustrated in Chart 1.

The chart shows the three large blocks corresponding to the stages mentioned, while each block includes a number of alternatives in the major current ceramic tile manufacturing techniques:

• raw materials preparation by a dry or wet procedure, • forming or moulding in the plastic state (extrusion) or forming in a semi-dry

state (pressing), • single-firing or double-firing (biscuit and subsequent applications)

Diagram of the ceramic tile manufacturing process Chart 1


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Raw materials treatments

Once the clays and other raw materials, as well as the additives needed in the final composition of the ceramic body, have been selected, the first manufacturing process stage consists of comminuting these constituents, obtaining a homogeneous mixture, and preparing the composition for the subsequent forming or moulding process. Today, there are basically two approaches: Clay quarry

• preparation by the dry method, in which the clays and other compositional

constituents are mixed and comminuted by mechanical means without the use of water, and

• preparation by the wet method, in which the clays and other compositional constituents are mixed with water for grinding or milling in rotating mills or ball mills. The resulting suspension then needs to go through a thermal process in order to remove water again and be converted into a semi-dry raw material.

Figures 1 and 2 schematically illustrate these processes.

Raw materials processing. Dry comminution.

Figure 1

Raw materials processing. Wet comminution.

Figure 2


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Current ceramic tile manufacture tends mainly to use the wet raw materials preparation route, particularly before forming by pressing. As already noted, the clays and other materials are milled in water in rotating mills (Figure 3), mixed and stored in large tanks, and then pumped (Figure 4) to a spray dryer (Figures 5 and 6), which evaporates the water and produces a raw material in the form of hollow spherical granules with a controlled moisture content (between 5 and 7%). This is the ideal raw material for subsequent forming by pressing.

Array of Alsing mills Figure 3

Pumping station in a spray-dried powder plant

Figure 4

General view of a spray dryer Figure 5

Schematic illustration of a spray dryer Figure 6


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Forming or moulding

The following fundamental stage in the ceramic tile manufacturing process is forming or moulding. Most current products are made by semi-dry pressing (raw materials with a moisture content between 5 and 7%) or by extrusion (raw materials of clayey consistency with a moisture content between 14 and 20%). The slip casting process is innate to the manufacture of sanitary ware, tableware, and ceramic products of complex geometry; in the case of ceramic tiles, it is only used in making border trims and other decorative elements, and consists of filling plaster moulds with an aqueous dispersion of raw materials (liquid clay). Semi-dry pressing (B)

The raw materials, in the form of small hollow spheres with a moisture content of 5–7% or in the form of solid grains with a controlled particle-size distribution, are subjected to mechanical pressing, which provides the ceramic tile with its definitive shape by application of a uniform pressure between 250 and 500 kg/cm2. The optimisation of this mechanical process has led to the manufacture of steadily thinner tiles with greater uniformity in regard to material density per unit volume, in addition to high green mechanical strength. That uniformity of the pressed raw material also allows the body to dry uniformly and avoids the defects that originate in differing behaviour of the material during the drying and subsequent firing processes.


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he use of moulds (dies) with engraved punches has also enabled relief to be incorpo

he first mechanical presses were entirely manual; a spindle movement and pressin

This high green strength has also allowed optimisation of tile surface treatments, without the piece first needing to be fired. In any event, semi-dry pressing has not only enabled advances in the single-fire manufacturing process but also a considerable increase in tile size without decreasing the quality and characteristics of the end product.

Mould with four outputs Figure 8 Pressing dies

Figure 7

Trated with great levels of accuracy. Tg force transmission system was later incorporated, using hydraulic or electric

energy. This was followed by the introduction of an automated clay feeder system for the press moulds, and optimisation of the pressing variables (essentially, pressing


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friction presses or hydraulic presses.

he manufacture of porcelain tile has led to the implementation of a new generat

The heading of this section contains a ‘B’: this is the letter that the product standar

xtrusion (A)

fter raw materials preparation, usually by the dry method, a plastic clay mass is obtaine

he facility used to press the clay forward, including the mould or die and the cutter t

pressure and uniformity of the operation). Semi-dry pressing takes place either in

Hydraulic press Figure 10

Mechanical friction press Figure 9

Tion of high-performance presses, whose most important innovation has involved

the diversified, stepped feed of different raw materials, achieving decoration effects in the ceramic substrate or body.

d uses to designate all tiles that are formed or moulded by a pressing process using slightly moistened powdered clay. E

Ad by homogeneous mixing in water. In this case, the resulting clay has a

moisture content of 14–20%, the body being pressed in a cylinder, through a die that provides the tile with its final geometry.

That cuts individual pieces of the same size from the exiting column of clay, is

known as an extruder or auger (Figures 11 and 12). The resulting individual tile is termed an extruded tile.

Figure 11

Figure 12

Extruders for plastic forming (clay)

This process is typical in the manufacture of ceramic brick and, to a lesser extent, in that of certain types of roofing tiles and, of course, ceramic tile. The ceramic tiles resulting from the extrusion process have grooves in the back, since they leave the extruder in pairs and then need to be mechanically separated, either in the manufacturing process itself or prior to tile installation (these tiles are also known as Spaltplatten or split tile).

The characteristics of this forming process differ from those of semi-dry

pressing, and the resulting product therefore also differs from that made by pressing. All tiles made by extrusion are designated by the letter ‘A’ in the product

standard.

Other forming processes (C)

Ceramic tiles may be shaped by other methods than the foregoing two methods. One such method is the traditional process, using manual or mechanical pressing of the clay, while another less frequent method is slip casting, in order to obtain pieces of complex geometry.

The slip casting process consists of pouring a liquid clay composition (aqueous dispersion of clay and other raw materials) into a plaster mould, so that it is deposited on the walls of the mould up to a certain thickness (vacuum casting), or it is deposited between two plaster moulds. The plaster absorbs the water of the deposited layer until an appropriate consistency is obtained.


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Drying

As it has already been remarked, all forming processes need to incorporate water in order to be able to take advantage of the clay’s plasticity. That water, independently of whether a surface treatment is applied to the green piece, must be removed before the firing process.


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Formerly, all ceramic objects were dried in

a natural process, in a more or less controlled way. Since the mid 19th century, with the introduction of mechanical forming processes and ensuing production growth, different industrial drying processes for ceramic pieces have been tried, recently including the reuse of hot air generated in the firing kilns.

Fast vertical tray dryer Figure 13

Current ceramic tile production has implemented drying equipment that

combines great productivity and uniformity in the operation devoted to water removal from the ceramic body. Drying production is matched to the green ceramic feed into the dryer and to the following manufacturing operations. Drying uniformity, which is absolutely essential to avoid tile breakage and deformation, is achieved by appropriate management of the hot air flow and physical separation of the tiles for uniform water removal through the ceramic tile cross-section and surface.

A further advantage is also obtained when tiles leave the dryer at an appropriate temperature for the subsequent engobe, glaze, and decoration applications onto the green piece, because this encourages rapid evaporation of the surface water that is added in these applications, though it is necessary to subject the ceramic tiles to complementary dryings before they undergo single firing.

Regularity and uniformity are vital in the drying operation, as well as in forming and firing, to keep end product dimensions constant, while also avoiding various defects stemming from both non-uniform drying and excess water in the green piece immediately before firing.

Glazing and decoration

In the past, engobes (clayey coatings) and glazes were applied onto the ceramic body that had previously been fired (biscuit), which was usually porous (allowing absorption of the water added by those applications), either before or after the decorations. These applications were entirely manual and only in the case of serial (repetitive) decorations were auxiliary items used to reproduce designs consistently (templates for outlining the graphics and stencils to fill in surfaces with a given contour). Hence the term painter section given to the tile factory department that performs the glazing operations and decoration applications on part of the production. View of a glazing line Figure 14

Though the decoration process with stencils led to great growth in productivity, it was transfer printing that enabled full serial decoration.


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The implementation of the screen printing

technique in ceramic tile decoration in the 1960s, first manually and later using printing heads (Figure 16), allowed the decorating process to be mechanised.

In turn, the incorporation of equipment for automated engobe and glaze application (waterfall, spraying, airbrushing, etc.) brought an end to the manual application of these coatings on the ceramic tile body (Figure 15).

In any event, the most important innovation was the concatenation in a glazing line or on a conveyor belt of all the treatments applied to the ceramic tile, either in a green or fired state (Figure 14). That glazing line allowed automatic feed of the tile substrate, whether as a biscuit fired in a double-fire manufacturing process or as a green body exiting the continuous dryers (in the single-fire manufacturing process).

Engobe and glaze applications as well as decorating techniques have evolved towards systems that provide great productivity, consistency in the parameters that control application uniformity, and a notable increase in decorative possibilities in terms of graphic complexity and wealth of colours. The implementation of the roller printing technique has notably enriched the diversity of the decorations obtained in industrial processing before firing (Figures 17 and 18).

Disc application (engobes and glazes) Figure 15

Screen printing head (mechanical screen printing)

Figure 16

Roller array for printing decoration Figure 18

Roller for printing decoration Figure 17

Though the use of mechanical screen printing has decreased compared with pad printing, at least in reproducing mineral effects, to be noted is the appearance of emerging techniques that represent, if they consolidate themselves, an advance in surface treatment possibilities (surmounting the constraints of other techniques). Thus, the following techniques are currently being implemented:

• Ink jet printing using fluids containing pigments and glazes with small

particle sizes (from nanometres to tenths of a millimetre) • Physical vapour deposition, used in obtaining metallised coatings and mirror

effects

Facsimile reproduction of mural decoration in theBaron of Vallvert Palace (Valencia, 18th century)using the ink jet technique. FRITTA (Alfa de Oro Award, Cevisama 2007)


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Water jet cutting

The application of this technique from the stone industry to the cutting of all types of ceramic tiles and especially of porcelain tile has allowed recovery of collections of the past, and custom reproduction of any design.

The mounting of complex compositions on polyethylene or glass fibre mesh

enables rapid, problem-free installation.

SOME CONSIDERATIONS ON THE MANUFACTURING PROCESSES Extruded tiles (A) ► Plastic forming and a harsher drying process (14-20% evaporation) lead to greater dimensional non-

uniformities ► To obtain a given mechanical strength, the extruded needs to be thicker than the pressed tile ► The extrusion process limits possible surface treatments on the green product (regarding embossing,

decorations, etc.) ► It is an appropriate process for the production of rustic tiles or for applications in which formal

aspects play a secondary role Pressed tiles (B) ► The improvements and innovations in the semi-dry pressing process (clay powder with 5–7%

moisture content) have allowed obtainment of large sizes, reduced thickness, and greater dimensional consistency, in addition to the incorporation of sophisticated surface treatment processes in the forming stage: embossing, mineral effects, glaze applications, etc.

► The drying and firing of tiles in a deck (dryers and single-deck kilns) have also contributed to the technical quality of these tiles and to greater dimensional uniformity

► The complete concatenation of the manufacturing processes has enabled quality control in real time ► By combining surface treatment techniques in the glazing line and on the finished product (low-

temperature decoration), current ceramic tile has no textural, chromatic, or decorative limitations ► The water jet cutting technology and pre-mounting on mesh have allowed re-emergence of the more

complex language of plane partitions, dating back to the Mediterranean tradition of Greek mosaics, Coptic art, and Hispano-Muslim wall claddings

► Technological maturity has enabled recovery of ceramic tiling systems, with their functional and/or decorative trims

Tiles obtained by other forming processes (C) ► These are only referenced in the standards in terms of their apparent porosity ► The tile production involved responds to three specific demands:

■ Terracotta or fired clay tiles fabricated by the traditional clay pressing process ■ Trims for swimming pools (scum troughs and borders), whose geometry does not allow them

to be formed by extrusion or pressing ■ Pieces of complex geometry for decorative purposes

In all cases, though it is not envisaged in standard EN 14411, the manufacturer should supply information on the main characteristics of these tiles


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A first classification based on the manufacturing process

The description of the manufacturing process allows a first simple classification of ceramic tiles to be derived, in terms of one or more process stages.

In terms of raw materials

Red-body ceramic tiles: tiles made from clays that, as a result of the firing process, acquire a colour that ranges from straw yellow to intense red or brown, depending on their iron oxide content and, to a lesser extent, their manganese oxide content. White-body ceramic tiles: tiles made from clays that contain no colouring oxides in their composition and, therefore, acquire a white or greyish-white colour as a result of firing. More or less porous ceramic tiles, depending primarily on the carbonate content in the clay composition and, in the second place, on the forming and firing processes. Vitrifiable clays, with a very low carbonate content, allow the ceramic body to be fired at temperatures above 1100ºC, this being essential for the manufacture of products with very low or no porosity (stoneware in general, and porcelain tile in particular).

In terms of forming method

Extruded tiles (A): tiles obtained by a forming or moulding procedure in which a plastic paste (body), usually a clay-based composition, is pressed through a die by means of an endless screw on a shaft that turns inside a steel cylinder or by obliquely mounted blades. The assembly comprising the endless screw and die is known as an extruder or auger. Ceramic tiles formed by extrusion are termed extruded tiles. These types of tiles include the extruded double tiles (namely, tiles that exit the extruder in the form of a double column and that, after they have been cut, dried, and fired, are separated by a light blow, thus yielding two individual tiles). A variant of the extrusion process may be considered post-extrusion lamination, sometimes with a pressing station. This yields tiles that may be quite large (200x900 mm) and very thin (4-5 mm). The Keraion® series by the German company Buchtal are fabricated by the lamination process, and the Barbieri & Tarozzi patent also uses this process.


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Pressed tiles (B): tiles made using the forming method based on a clay composition in powder or granular form, with a specific grain-size distribution and low moisture content (below 7%). Mechanical pressing of this moisture-containing powder gives rise to the pressed compact. This forming process is known as dry or semi-dry pressing. Vibrocompaction (semi-dry or high-pressure pressing) may also be considered a pressing variant for the production of very thin, large tiles [2700x900x3 mm]. This process has been patented by System under the trade name Laminam®. Tiles obtained by other forming or moulding methods (C), which include those already mentioned obtained by plastic forming of the clay, either manually or mechanically, this being, respectively, the usual way of making terracotta tiles more or less artisanally or of fabricating them industrially with a rustic appearance. The plastic pressing method is also applied to volumetric borders and cappings. The slip casting technique has been brought back again for very complex geometries. As already noted, the technique consists of pouring an aqueous dispersion of clays into plaster moulds. In the European standard, this aqueous dispersion of clays is referred to as a slurry.

In terms of firing

Single-fired tile: this refers to the ceramic tile manufacturing process that consists of just one single firing process, though the tile may subsequently be subjected to other thermal processes for low-temperature firing of decorations (below 900ºC). Double-fired tile: this refers to the ceramic tile manufacturing process in which the ceramic body is fired first, thus yielding the biscuit, followed by a second firing for the glaze(s) and decorations. Third-fire tile: this refers to tiles that receive decorative applications and other surface treatments, which are subjected to one or more additional firings below the peak firing temperature of the base tile.

In terms of glaze application

Glazed tile (GL): this refers to ceramic tiles whose fair face is coated by one or more glazes. Unglazed tile (UGL): this refers to ceramic tiles whose fair face is not coated, either wholly or in part, by any glaze. This tile family includes terracotta tile, unglazed rustic stoneware, and porcelain tile.


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In terms of mechanical treatments on the finished product

Polished tiles: in these tiles the fair face has been subjected to a complex abrasion process with a set of grinding tools containing differently sized grain in order to obtain a mirror-gloss surface. This treatment is applied to the ceramic body (porcelain tile) and to the glaze of certain types of glazed tiles. Rectified tiles: when the dimensions of the tiles exiting the kiln are small, the tiles may be machined by mechanical cutting and edge-bevelling to a precise size, with variations below ± 0.5 mm in length and width. Tiles that are produced by abrasive water jet cutting in order to obtain complex shapes for borders or mosaics, which are then pre-mounted on mesh.

In terms of intended use

The manufacturing process itself indirectly delimits the use of a ceramic tile, since a given thickness, size, and characteristics of the ceramic body will make it suitable for a particular application, a distinction being made between those tiles that, owing to their mechanical strength, may be used for a treadable space and those that, in contrast (low mechanical strength and thinness), can only be used in a non-trafficked surface.

In addition, depending on their shape, ceramic tiles may be classified as special pieces or trims when they are to be used as junctions, in order correctly to join an abutting construction element, or to separate/delimit spaces for functional or decorative purposes. As a result, ceramic tiles may be classified in terms of intended use as:

Ceramic cladding or wall tiling: ceramic tiles that clad a wall or facing. In general, this is the name that should be given to ceramic tiles that are intended for a location in which they will not be walked on. In Spain, these are known as azulejos (earthenware tile or wall tile). Ceramic flooring: group of ceramic tiles that cover floors and that are also going to be walked on. Special tiles: ceramic tiles that, owing to their geometry or decoration, have a specific function in a wall tiling or flooring.

This section includes:

• Tiles that serve as junctions for changes of plane (coves and angles) • Pieces that make up a swimming pool scum trough system and nosings

• Pieces that make up a stair system, especially treads with nosing, and cheeks

• Pieces that serve to separate or decorate (listels, borders, cappings).

TYPOLOGICAL CLASSIFICATION BASED ON MANUFACTURING PROCESS

Coloured body or substrate: red body → In terms of raw materials White body or substrate: white body Tiles of very high porosity (group III) Tiles of high porosity (group IIb) Tiles of intermediate porosity (group IIa) Tiles of low porosity (group Ib)

→ In terms of raw materials, plus formingmethod and firing process

Tiles of very low porosity (group Ia) (E ≤ 0.5%) Extruded tiles (A) Pressed tiles (B)

→ In terms of the forming or moulding technique

Tiles formed by processes other than extrusion and pressing (C) Glazed tile (GL) → In terms of the presence of glaze on the tile

fair face

Unglazed tile (UGL)

Single-fired tile (one single firing) → In terms of the number of firings that the tile undergoes

Double-fired tile (two firings)

Third-fire tile (low-temperature decorative treatments, one or more firings) Rectified tiles, when the ceramic body is subjected to cutting and bevelling Tiles obtained by water jet cutting to achieve formats with complex contours

→ In terms of additional treatments after firing

Polished tiles (mechanical polishing of the porcelain tile body or mechanical polishing of the glaze in glazed tiles) Cladding or wall tiling: non-treadable tiles Flooring: treadable tiles

→ In terms of tile mechanical strength or geometry, in direct relation with intended tileuse Trims: tiles with a specific function

Chart 2


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Note ■ There is no direct link between fired tile body colour and tile quality or performance ■ White-body tiles are not better than red-body tiles ■ Single-fired tiles are not of better quality than those made by several firing processes


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On the other hand, since the dawn of Silicate Chemistry, Materials Science, and Ceramic Technology, most ceramic product classification have used the following two (readily identifiable and quantifiable) technical parameters to categorise all ceramic products generally, and tiles in particular:

• Colour of the fired ceramic body, also known as the biscuit: white or near-

white, and coloured. • Fired body water absorption capacity, broken down into large groups that

match large families of traditional ceramics, from very absorbent products to porcelain.

The following chart reproduces this traditional technical classification in regard

to ceramic tiles.

FIRST CLASSIFICATION OF TYPES OF CERAMIC TILES

Fired body colour

Porosity Glaze Technical/trade name

No (UGL) Fired clay tile Terracotta tile Other local names

High/Very high

Yes (GL) Earthenware tile or wall tile Majolica tile Majolica

No (UGL) Rustic stoneware Industrial stoneware Clinker

Intermediate/Low

Yes (GL) Glazed stoneware tile Single-fired stoneware Stoneware flooring

No (UGL) Porcelain tile Clinker

Coloured

Very low

Yes (GL) Glazed porcelain tile Glazed stoneware tiles Clinker

No (UGL) High/Very high

Yes (GL) White-body wall tile Earthenware tile

No (UGL)

Intermediate/Low Yes (GL)

Earthenware tile White stoneware White-body stoneware flooring

No (UGL) White porcelain tile

White

Very low Yes (GL) Porcelain mosaic

Chart 3


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The foregoing classification displays a direct link between trade categories and the technical classification. The following chart reproduces the previous one with inverted columns, and lists the product codes according to European standard EN 14411 in the last column.

LINKS BETWEEN THE COMMERCIAL AND TECHNICAL CLASSIFICATIONS

Trade name Technical family Surface Water

absorption (E) %

Product group EN 14411

TERRACOTTA TILE OR FIRED CLAY TILE

Coloured, very porous biscuit

Unglazed UGL E >10% AIII

EARTHENWARE TILE OR WALL TILE

Coloured or white, very porous biscuit

Glazed GL E >10% BIII

RUSTIC Low porosity and coloured

Glazed and unglazed

GL and UGLE < 5% AIb, AIIa-1, AIIa-2,

BIIa, BIb

GLAZED SINGLE-FIRED FLOORING

Low porosity, coloured or white

Glazed GL E < 5% BIb, BIIa STONEWARE

CLINKER Low porosity and coloured

Glazed and unglazed

GL and UGLE < 3% AIb, BIb

TECHNICAL Unglazed UGL E < 0.5% BIa, AIa PORCELAIN

TILE GLAZED

Very low porosity, coloured or white Glazed

GL E < 0.5% BIa, AIa


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By way of final summary, a table follows that relates the commercial families to main tile characteristics, as an advance of the documentation that may be accessed under the head ‘physico-chemical characteristics’.

COMMERCIAL FAMILY

PREFERENTIAL PRODUCT GROUP

EN 14411 NOTEWORTHY CHARACTERISTICS

TERRACOTTA TILE OR FIRED

CLAY TILE AIII UGL

• Lacks dimensional precision • Does not withstand frost/thaw cycles • Is stainable and needs protective treatments • Requires regular maintenance • Mechanical strength depends on thickness

EARTHENWARE TILE OR WALL

TILE BIII GL

• Dimensionally precise, though it is recommended to control tolerances in large sizes (from 30x30 cm)

• Has low mechanical strength owing to thinness. Only appropriate for cladding facings or walls

• Does not withstand frost/thaw cycles • Chemical and stain resistance depends on the nature of

the glazes and surface finish • Impermeable fair face, which requires no maintenance

RUSTIC STONEWARE

AIb UGL AIIa-1 UGL

AIb GL AIIa-1 GL

• Lacks dimensional uniformity, especially in tile marketed as natural

• Does not withstand frost/thaw cycles • Has high mechanical strength • Stainability depends on surface texture and whether

glaze is present

CLINKER TILE

AIb UGL BIb UGL AIb GL BIb GL

• Dimensionally precise in the marketed sizes (12x24 cm, 20x20 cm)

• Has high mechanical strength and chemical resistance • Some types withstand frost/thaw cycles • Has variable stainability

STONEWARE TILE BIb GL

GLAZED STONEWARE FLOORING

BIIa GL

• Lacks dimensional precision. Should be marketed with a calibre code

• Does not withstand frost/thaw cycles, except for some BIb products

• Withstands impairment of appearance (mechanical and/or chemical aggressions) depending on type of glaze

• Has low stainability

GLAZED PORCELAIN

TILE BIa GL

• Has high mechanical strength • Withstands frost/thaw cycles • Remaining characteristics like those of stoneware tiles

PORCELAIN TILE BIa UGL

• Has high mechanical strength and chemical resistance • Withstands frost/thaw cycles • Lacks dimensional precision. Needs a calibre code or

rectification • Has variable stainability in polished finishes

Ceramic systems

Within the trade offer for the different tile families, it is necessary to consider ceramic tiling systems, these being sets of ceramic pieces that serve comprehensively to tile a construction element without the need to cut any materials, or that have a functional and/or aesthetic purpose. Stairs

Set of ceramic pieces that serve to clad stair steps and join these to adjacent construction elements. The product offer also sometimes includes ceramic banisters and balusters.


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STAIRS

Name Definition

Tread Ceramic tile with special edge termination (lip), the part adjacent to that lip usually being profiled, to constitute a stair tread

Tread corner Ceramic tile with special termination (lip) at two adjacent edges, to constitute the tread outside border

Riser Ceramic tile, usually glazed and decorated, as long as the tread, whose widthcorresponds to standard step height

Nosing or edge Piece containing a longitudinal anti-slip profile, for the outer part of the step, complemented with a flat tile of the same width, to complete the step cladding

Cheek Piece of irregular geometry, adapted to the step cross-section, which serves as stairskirting. The model and its mirror image are manufactured, in order to be able to clad the left and/or right skirting of a stair

Handrail or banister Piece with a concave or rectangular cross-section to clad the top of a stair railing,which is usually of masonry

Set of tile items for stair tiling

Tiling of swimming pool basins and scum troughs Set of tile items that allow changes of plane in swimming pool basin tilings,

including underwater stairs, in addition to scum trough systems.

Ceramic systems for junctions at abutments and changes of plane in tilings in water environments

SWIMMING POOLS

Designation Definition Nosing Ceramic piece that serves to clad the edge of a conventional swimming pool

without a scum trough, which may have a more or less complex cross-section, usually with anti-slip profile and end moulding. Nosing types include the Finnish system, Zurich system, and Portuguese system, a flat joining part being incorporated with the inner tiling of the swimming pool. The Wiesbaden A and B system nosings include a small scum trough, in addition to a piece with a water-drainage hole

Nosing corner Complementary trim to the nosing for swimming pool corners, without the need to cut any pieces

Cove or concave shape

Piece with a concave cross-section (quarter circle) for joining abutting facings

Cove angle Piece complementary to the cove to be fitted in three-sided pieces

Channel Ceramic piece with a more or less complex geometry for leading the water alongthe edges of a swimming pool. It includes a piece with a centre hole

Scum trough U-shaped piece with a more or less complex geometry, depending on the different finishing systems, which serves as a scum channel.

Scum trough angle Piece complementing the scum trough, for the channelling in the corners


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Skirtings

System or set of pieces which, on the one hand, allow changes of plane in a ceramic tiling and, on the other, serve decoratively to delimit surfaces (listels, cappings, borders, etc.).


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SKIRTINGS

Name Definition Round-edge tile Ceramic tile with a rounded edge (semicircular termination of the fair edge), for

corner junctions Double round-edge tile

Ceramic tile with two adjacent rounded edges (semicircular termination of two adjacent edges), for corner junctions

Bevelled earthenware tile or wall tile

Ceramic tile with bevelled fair edges (angle ≤ 45º in relation to the tile surface), fordecorative purposes

Capping Ceramic piece that is usually three-dimensional or embossed, used to delimit parts of a tile dado or wainscot. The length corresponds to the skirting base tile

Capping angles (in- or out-angles)

Pieces complementary to the capping, with the same cross-section, for joins with other facings without the need to cut any pieces. They may be concave or convex

Dividers or strips Very narrow pieces, of the same length as the base tile that constitutes the tile dado or wainscot, which serves to delimit parts of the tile dado or wainscot. Also termed listel or fillet. The term listelo is inappropriate, since it is an Italian word.

Divider angles Pieces complementing dividers or strips, of the same cross-section, for junctions with other facings without the need to cut any pieces. They may be concave or convex

Beads Pieces with a cylindrical geometry (quarter cylinder), which serve as junctions with other facings without the need to use mitres or to cut any pieces. They are used both horizontally and vertically. Also called coves

Bead angles Pieces complementing beads, of the same cross-section, for joining three-sidedpieces and corners. They may be concave or convex

Skirting Ceramic piece, of the same length as the base piece, sometimes in a square format, with formed edge profile, as the bottom part of the skirting and junction with the flooring. By extension, this term should be used for all pieces that constitute the skirting of a flooring, usually with a rectangular cross-section and same length as the floor tile

Skirting with top bevel

Special piece for skirting with a bevel termination

J-shaped skirting Ceramic piece with a J-shaped cross-section, which serves as a junction with the flooring

Coves Term equivalent to bead, and associated most frequently with the concave piecesthat serve as junctions with other facings

Cove angles Trims complementing the cove, with a triangular shape, for joining three-sidedpieces


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Other trims

There are further specific ceramic trims and special pieces for construction finishes. These products may be broken down on the basis of functionality or personality in the Art of cladding surfaces. Functional products include window sills and systems for ledges and benchtops. Personality-focused products include inserts or olambrilla, trencadís (tile fragments), and mosaics (tiles smaller than 10x10 cm).

OTHER TRIMS

Name Definition

Systems for kitchen benches or ledges and laboratory benches

Group of tiles designed to prevent liquids from spilling or penetrating into bench corners. Applied especially in laboratory benches and now also recovered for use in the most qualified tiling offer for kitchens. They include tiles with raised edges, corners with raised edges, tiles with a J-shaped edge, tiles with centre profile and opening for plumbing facilities, junction pieces, and angle trims.

Sills Ceramic pieces designed with the classic inverted ‘M’ at the edge to facilitate water evacuation and keep water from running down the facade

Sill with raised edge

Particular window sill with raised lip on the side opposite the outer edge to protect the junction with the carpentry and keep water from seeping in through the joint

Mosaic Small-sized ceramic tile, usually 5x5 cm or smaller, though some call mosaic any ceramic tile with a total surface area below 100 cm2. Mosaic is supplied as face or back pre-mounted panels, customarily measuring 40x40 cm

Trencadís The term refers to inlaid or embedded ceramic tile fragments (hence of irregular geometry), juxtaposed to provide a ceramic tiling with contrasting colours. At present, they are also marketed pre-mounted according to particular decorative programmes and are used both in wall tiling borders and flooring borders

Mitre 45º cut made on the bottom or rear edge of a ceramic tile to allow the fair faces of two adjacent tiles to touch at their outer edges, avoiding a bevel angle. By extension, the term mitre refers to the tile that has this inner bevel edge

Insert Small-sized tile, dimensionally coordinated with the base tile of a flooring. It usually has a colour that contrasts with or has different decorative effects from the flooring, for insertion in the flooring

Olambrilla Piece equivalent to the insert and traditional Spanish name for tile measuring 5x5 cm or smaller, glazed, decorated, or embossed, inserted in a terracotta tile or fired clay tile flooring

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