Glossary of Industry Terms



Packing house tile

Similar to quarry tile but usually of greater thickness.

Paper and wire

Tar paper and wire mesh (or metal lath) that are used as a backing for the installation of tile.

Paper mounted ceramic mosaics

Ceramic mosaic tiles inounted cm paper. Paper is applied to face of tile in slicets approximately twelve (12) incites wide, twentyfour (a-1) inches long.

Pate dare (hard paste)

A French term designating ceramic whitewares fired at relatively high temperatures. (ASTM C 242).

Pate tendre (soft paste)

A French term designating ceramic whitewares fired at relatively low temperatores. (ASTM C 242).


Unglazed porcelain or natural clay tile formed by the deist-pressed method and similar to ceramic mosaics in composition and physical properties but relatively thicker with 6 in.- or more of facial area. (ASTM C 242).


See Orangepeel; Shivering.

Pencil rod

Reinforcing steel rod with a diameter of ‘A”.


A lithium mineral of theorical composition Li.,O ‘ A1203 ‘ 8Si02 which transforms on heating to a beta spodumene-silica solid solution product of very lo%v or nil thermal expansion.


A simplified system of measuring acidity or alkalinity irrespective of the acid or alkali involved; in which neutrality is 7.0, e.g., Mineral Acid Solution is 1.0-2.8, Acetic Acid Solution or Citric Acid Solution is 3.0-4.0, Ammonia is 9.0, Lime Water is 12.0.

Physical properties of ceramic tile.

-[‘]lose properties as measured by ASTM tests.


Imperfections in the surface of a ceramic body or glaze resembling pin pricks. (ASTM C 242).


Indentations in the finished surface of individiial 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.


Development of relatively small cavities in a surface, due to phenomena such as corrosion or cavitation, or, in concrete, localized disintegration. (See also Popout.)


Pounders per lineal inch.


A cementitious material or combination of cementitious material and aggregate that, when mixed with a suitable amount of water, forms a plastic mass or paste which when applied to a surface, adheres to it and subsequently hardens, preserving in a rigid state the form or texture imposed during the period of plasticity; also the placed and hardened mixture. (See also Stucco.)

Plastic cracking

Cracking that occurs in the surface of fresh concrete soon after it is placed and while it is still plastic.

Plastic flow

See Creep

Plastic pressing

See Pressing, wet


A complex property of a material involving a combination of qualities of mobility and magnitude of yield value; that property of freshly mixed cement paste concrete, or mortar which determines its resistance deformation or ease of molding.


A material that increases plasticity of a cement paste, mortar, or concrete mixture.


Perpendicular to a true level.

Plumb – scratch

An additional    scratch coat that has been applied to obtain a uniform setting bed on a plumb vertical plane.

Pointing mix

Mortar with a consistency of stiff paste. The mix is forcibly compressed into the tile joints where it hardens.

Pointing trowel

The pointing trowel or pointer is probably the most essential tool in the trade. It comes in sizes ranging from 4″ to 7″ in length, but the 6″ trowel is the most popular. The tilesetter uses this trowel in every phase of the work, especially for straightening tiles on walls and floors, marking floated surfaces, filling small depressions on float coats, buttering tiles and trim work, and placing mortar in areas that are too small for the flat trowel. The butt of the handle is used for tapping in tiles that are not on a true plane with the rest of the tileNvork. The trowel’s flat working surface must be protected. The tilesetter should not use it to pry or chop hardened materials such as concrete or plaster.

Poisson’s ratio

The ratio of transverse (lateral) strain to the corresponding axial (longitudinal) strain resulting from uniformly distributed axial stress below the proportional limit of the material; the value will average about 0.2 for concrete and 0.25 for most metals.


A thermoplastic high-molecular-weight organic compound used in formulating protective coatings or, in sheet form, as a protective cover for concrete surfaces during the curing period, or to provide a temporary enclosure for construction operations.

Polychrome decoration

A multicolor decoration. (ASTM C 242).


The breaking away of small portions of a concrete surface due to internal pressure which leaves a shallow, typically conical, depression.


A glazed or unglazed vitreous ceramic whiteware used for technical purposes. This term designates such products as electrical, chemical, mechanical, structural, and thermal wares when they are vitreous. (See also, Alumina porcelain; Cordierite porcelain; Forsterite porcelain; Steatite porcelain; Titania porcelain; and Zircon porcelain.) (ASTM C 242).
Porcelain process. The method of producing glazed ware by which a ceramic body and glaze are matured together in the same firing operation. (ASTM C 242).

Porcelain tile

A ceramic mosaic tile or paver that is generally made by the dust-pressed method, of a composition resulting in .t tile that is dense, finegrained, and smooth with sharply formed face, usually impervious. Colors of the porcelain type are usually of a clear, luminous type or granular blend thereof. (ASTM C 242).

Porosity, apparent

The relationship of the open pore space to the bulk volume, expressed in percent. (ASTM C 242).


A method of prestressing reinforced concrete in which tendons are tensioned after the concrete has hardened.

Pot life

The period of time during which a material maintains its workable properties after it has been mixed.


All fired ceramic wares that contain clay when formed, except technical, structural and refractory products. (ASTM C 242).


A siliceous or siliceous and aluminous material, which in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties.


A concrete member that is cast and cured in other than its final position; the process of placing and . finishing precast concrete.

Precast concrete

Concrete cast elsewhere than its final position.


The term used to describe mortar that has been placed and allowed to harden prior to bonding tile to it with thin-set materials.

Pregrouted tile

A surface unit consisting of an assembly of ceramic tile bonded together at their edges by a material, generally elastomeric, which seals the joints completely. Such material (grout) may fill the joint completely, or partially and may cover all, a portion or none of the back surfaces of the tiles in the sheets. The perimeter of these factory pregrouted sheets may include the entire, or part of the joint between the sheets or none at all. The term edgebonded tile is sometimes used to designate a particular type of pregrouted tile sheets having the front and back surfaces completely exposed.


See Pressing, dry; Pressing, hot; Pressing, wet.

Pressing, dry

Forming ceramic ware in dies from powdered or granular material by direct pressure. (ASTM C 242).

Pressing, hot

A jiggering process wherein a heated profile tool or plunger is employed. (ASTM C 242-72)

Pressing, wet (plastic pressing)

Forming ceramic ware in dies from a plastic body by direct pressure. (ASTM C 242).

Prestressed concrete

Concrete in which internal stresses of such magnitude and distribution are introduced that the tensile stresses resulting from the service loads are counteracted to a desired degree; in reinforced concrete the prestress is commonly introduced by tensioning the tendons.


A method of prestressing reinforced concrete in which the tendons are tensioned before the concrete has hardened.

Primary clay (residual clay)

A clay which remains geologically at its site of formation. (ASTM C 242).


See Process, dry;

Process, wet

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. (ASTM C 242).

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. (ASTM C 242).

P.S.I. or psi

Pounds per square inch, a unit measure of pressure.


A highly porous and vesicular lava usually of relatively high silica content composed largely of glass drawn into approximately parallel or loosely entwined fibers, which themselves contain sealed vesicles.

Pumped concrete

Which is transported through hose or pipe by means of a pump.


See Neat cement.

Pure coat

A thin coat of pure portland cement which is used to bond tile to mortar.


A hydrated aluminum silicate mineral of the theoretical composition A12 03 – 4Si 02 – H2 O, having physical properities in the raw state resembling mineral talc. (ASTM C 21)