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Confused about 'rectification', or unfamiliar with terms like 'back buttering'? Whatever your existing knowledge, this is a layman-friendly guide to all terms tiling related.

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An unglazed natural clay or porcelain tile for exterior use in such areas as drives and patios.

PEI Rating

Named after the Porcelain Enamel Institute (PEI) in the USA, these abrasion resistance classifications indicate how well a glazed tile will withstand friction, scratching, wear and tear, etc., when subjected to various levels of traffic.

  • Class 1  - Walls only

  • Class 2  - Light residential

  • Class 3  - All residential, light commercial.

  • Class 4  - Commercial

  • Class 5  - High traffic areas, heavy commercial/industrial

Pendulum Test

The pendulum coefficient of friction test was developed with the intention of providing a ‘portable’ method of assessing slip resistance on flooring.  The standardised test, as defined in BS 7976: Parts 1-3, 2002, is used to measure skid resistance of tiles and other floorings, particularly important in testing non-slip surfaces. A swinging imitation heel, with a standardised rubber sole, is swept over a set flooring area in a controlled way, with the slipperiness of the flooring shown as a pendulum test or slip resistance value.


Small indentations in the finished surface of an individual tile, typically the result of corrosion, cavitation, or manufacturing defects.


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


The tile's surface is buffed by a machine, resulting in an even, smooth and highly reflective surface.

Lightly Polished

The tile's surface is polished to a softly reflective sheen.

Polymer Modified

Polymers were first used as additives to cement mortars and concrete during the 1920s, when natural rubber latex was added to road paving materials. There has been considerable subsequent development of commercial products, called admixtures.  Polymer-modified Portland cement is widely used in the production of tiling adhesives and grouts to improve application and the performance characteristics, including easier handling, increased tensile and flexural strength, enhanced adhesion, improved water resistance, and greater durability. It also tends to prolong the hydration period, giving increased density and shear strength, extending the working time and, of particular importance with grouts, promoting colour uniformity in the end product.


These tiles are made with white clay and fired at a high temperature making them dense, hardwearing and perfect for floors. They have an extremely low water absorption rate of less than 0.5% making them well suited for bathrooms and wet rooms. Porcelain tiles can be glazed or unglazed.

Pot Life

The period of time during which a material, such as adhesive or grout, maintains its workable properties after it has been mixed.


A liquid, typically acrylic-based, used for preparing floor and wall backgrounds prior to fixing of ceramic/ mosaic and natural stone tiles. PVA-based primers are not normally recommended for tiling applications, as the water content changes the constituency of the PVA, returning it to a tacky state that prevents the adhesive from penetrating the substrate which could lead to tiles de-bonding.

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