I, J, K, L. (imbrication - linen fold)

Imbrication: a fish scale ornamentation.

Impervious: forming a barrier to water in its liquid state.

Impost Moulding: the horizontal moulding along the tops of piers (where the arch springs from); the moulding round the arch is called the archivolt.

In situ: in the permanent or original situation.

Insertion mould: basically a reverse plaster mould containing one or more lines of enrichment. This or these are reproduced by having a pliable mould to the complete line in either gelatine or PVC.

Intonaco: a relatively simple Italian stucco technique with sands, a little crushed brick and lime.

Jamb: the side of a window or door opening.

Key: a mechanical bond produced by the physical interpenetration of the first plaster coat with the background and of one plaster coat with another. The plaster key on lath background is made by the nibs that are formed between and behind the laths by pressure with the float when laying on the first coat. The nib is ideally a dovetail shape, but in practice just an irregular nib or scratching.

Keystone: the highest centre stone in an archway.

Knocked up: material after it has been gauged ready for use.

Label: a hood mould.

Laps: small square or rectangular portions of canvas used to assist the main reinforcing in fibrous plaster casts. They are soaked in plaster and pushed into the back of the cast.

Larry: a long-handled mixing tool for mixing lime putty and coarse stuff. It is like a hoe with a half-moon shaped hole in its blade.

Latent hydraulic binder: a pozzolan. It can combine with lime and water to give a hydraulic set.

Lath, lathing: the riven or sawn wood which is nailed up to form the back ground to some plaster systems. Typical dimensions for a lath are 25mm wide, 5 mm to 6 mm thick, and 900 mm to 1500 mm long. The word lathing is also used to describe alternative materials which do a similar task, for example, expanded metal, perforated and ribbed sheet materials, mesh and reeds.

Lean Lime: Class B lime. A lime prepared from a limestone or chalk which contains impurities which do not contribute to a hydraulic set, but act instead as part of the aggregate in a mortar.

Lime: the root meaning of the word is a sticky substance and from that it has developed several later meanings. In this context, the word lime includes all of the oxides and hydroxides of calcium and magnesium, but excludes the carbonates. Thus quicklime and slaked lime we would call lime, but chalk and limestone we would not call lime.

Lime concrete: a building material cast from aggregate (usually sand and stone) in a matrix or hydraulic lime or of lime and pozzolan, but not using Portland cement.

Lime pit: a covered tank formed in the ground to store lime putty in moist conditions.

Lime putty: slaked lime stored in an excess of water to fatten up. This process also enables less reactive particles to be hydrated before use. A distinction should be drawn between putty prepared from dry hydrate and putty run directly from quicklime.

Lime water: a saturated solution of calcium hydroxide in water. When lime putty settles out from milk of lime the clear liquid above is limewater. As this evaporates it becomes covered with a clear layer of calcite. Lime water may be used for consolidation of porous materials.

Limestone: any rock or stone whose main constituents are calcium carbonate or calcium and magnesium carbonates.

Limewash: a simple form of paint prepared from lime, with or without various additives. It is most suitable for use on walls and on ceilings, both internally and externally.

Linen fold: a popular pattern resembling the folds of a napkin. More commonly found in wood.
 
 

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