A, B. (abacus - breaks and returns)

 Abacus: the top moulding of a capital, derived from the Greek ëabaxí.

Acanthus: a plant commonly called ëBearís beechí whose leaves are often used for decorating the Corinthian and composite capitals.

Active hydraulic binder: a hydraulic binder which acts without the addition of an activator such as lime. In effect this includes hydraulic cements and hydraulic limes, but excludes pozzolans.

Accelerator: a material used to accelerate the setting of a variety of plaster and render mixes. Examples are ëalumí for plaster, ëcalcium chlorideí for ordinary Portland cement and sand mixes.

Acroteria: small pedestals found at the extremities and apex of a pediment. Originally intended to support figures. Can also be termed ëpinnaclesí.

Additives: these are materials other than aggregates, cements, lime or plaster used in the production of plaster and render mixes, eg.: accelerators, colouring agents, plasticizers, hardeners, water proofing compounds, etc.

Adhesion: the bond between a wet plaster or render mix and the backing to which it is to be applied.

Aggregate: the hard filler materials, such as sand and stones, in plasters and renders.

Air limes: limes which set through carbonation rather than through chemical reaction with water.

Air slaked lime: the mixture of calcium carbonate, hydroxide and oxide which results when a quicklime slakes naturally in moist air.

Alcove: a recess in a wall or room often vaulted or coved.

Angles: intersections of plaster or render surfaces at varying degrees. Can be either internal or external angles.

Angle bead or Angle-staff: a round member found at exterior angles.

Annulet: a ring - often applied to the fillets under the Doric Capital.

Applique: moulded or carved ornament fastened to a subject as distinguished from being planted, which is embedded in its surface.

Arabesque: a scroll ornamentation of leaves, animals and humans shapes.

Arcade: a series of arches.

Arch: a system of bridging over an opening, resting onto piers and having a curved soffit, intrados or archivolt. They can be semicircular, segmental, stilted, pointed/triangular, curved or horseshoe form.

Architrave: a moulding formed around a door or window opening, the lowest member of an entablature.

Archivolt: the moulding around an arch.

Armature: a rod or framework of iron or other material built into a surface, usually a wall or ceiling, for the purpose of strengthening or providing additional support to build up plaster or render to form features in relief, usually decorative.

Arris: the sharp or external angle formed by the intersection of two plane or curved surfaces.

Artificial pozzolan: A man-made material which will react with lime and water to give a hydraulic set, eg. brick dust.

As dug (sand): sand exactly as it is dug from the quarry, without any sieving or washing.

Ashlar: squared and regular masonry finish. External plasters/renders are often applied with a smooth and plain face marked and scribed to imitate the block form of Ashlar masonry.

Astragal: a small round moulding which encircles the top or bottom of a column. Often separates the column shaft from the capital.

Atlantes: male figures used instead of columns.

Autogenous healing: the self healing of fine cracks in a plaster or render from the binder already in that plaster. Free lime is transported by moisture into the cracks.

Axis: a straight line, real or imaginary which passes through the centre of a building or object.

Background: a surface other than any plaster rendered surface on to which plaster or render is applied eg: stone, brick, concrete, lathing, etc.

Backing: the plaster or render undercoats applied to a background. Also called render coat, floating coat or scratch coat.

Bagged lime: usually dry hydrate of lime. Calcium hydroxide in a dry power from and sold in sacks.
 

Ball flower: a formed Gothic moulding representing four curved and rounded petals enclosing a ball.

Baluster: a small round or square pillar or pilaster, serving to support a rail or cornice, generally ornamented with mouldings and other decorations.

Balustrade: a connected series of balusters surrounding balconies, terraces, parapets, steps, staircases, tops of houses, etc. They are sometimes used solely as ornaments.

Band: a flat often profiled moulding.

Bandeler: a plain moulding.

Banker: a raised board on which plaster is stored beside the plasterer for immediate use.

Baque: an annular moulding.

Base or Base moulding: the lower part of a column, pedestal or wall.

Bas-relief: a model or cast in which the figure or figures do not project in full from the ground.

Batter: where a wall is built intentionally with a sloping face ? the slope is termed ëthe batterí.

Bay: a compartment of a building; the space between two pairs of columns or two roof principals.

Bay-window: a bow-window; projecting beyond or from the general surface of the building.

Bead:  a small round moulding.

Beaded: a string of balls or beads; often used as a moulding.

Bed-mould: the moulding under the bold projection of a cornice or frieze.

Bevel: a slope made by cutting of an angle except one of 90o. Anything that is not square is generally called a bevel angle.

Binder: generally the term used for the material that causes the mix to harden or set. Traditionally this may have been hair, sisal or tow, etc.

Blister: a scaly protuberance on the surface of plaster work, caused by the blowing or bursting of improperly burnt or slaked lime, or by the presence of foreign matter.

Blocking Course: a plain course of stone or cast stone over a cornice; a plain string course.

Blub: a trade term for holes in moulds, casts, and plaster work, caused by contained air and careless manipulation of the materials.

Blue Lias lime: a hydraulic lime prepared from some of the limestones in the Lias formation which runs across England and the south of Wales. This was used extensively for engineering and external work in the nineteenth century.

Bond: the adhesion between the background and backing and the backing and finishing coats.

Boning: the operation to align or level angles, lines or objects by purely visual means. It is performed by placing two parallel straight edges on an object, and sighting on their upper edges to see if they range.

Boning-rods: are used for boning. They are made in the shape of the letter ëTí. The head giving the point of sighting.

Boss: an enrichment often used at the intersections and ends of Gothic mouldings.

Bowtel: a round moulding.

Bracket: a skeleton support for plaster mouldings, also used in solid plastering/rendering as a means for saving materials. Can be made of wood and metal, shaped to the required contour and fixed in position. In fibrous plastering they can give additional strength in the form of canvas and plaster covered members fixed on the backs of plaster casts, generally across the width.

Breatheability: the extent to which a building material is able to allow moisture to move to the surface and evaporate harmlessly.

Building lime: lime of a suitable nature and in an appropriate state for building uses.

Bust: a portrait statue of a person comprising the head, shoulders and breast.

Breaks and returns: the interruption in the continuity of mouldings and plain surfacing is the break and the return is the continuance of the same work at a different angle.
 

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