Glossary - L
Lacquer
A term usually applied to coatings that dry entirely by evaporation of the solvent.
Lagging
The process of covering vessels or pipes with a non-conducting material to prevent loss or ingress of heat.
Laitance
A milky type deposit from newly applied concrete.
Lantern light
A rectangular projection on a flat roof, usually with vertical sides and wholly or partly glazed to admit light and air to the building beneath.
Lap
In painting, the expression 'to lap' refers to the joining up of a section of painting to a previously painted, but still wet, section. Normally it is important for the previously painted edges to be 'kept alive' so that the paint can be well worked into the previously painted section and subsequently dry without the lap showing.
Latex paint
Water-based paint made with synthetic binders such as 100% acrylic vinyl, acrylic terpolymer or styrene acrylic. Latex paint dries fast, flows smoothly and cleans up easily with water.
Lath and plaster
Describes a form of ceiling or wall construction in which narrow strips of wood are fixed to the framing or joists over which plaster coatings are spread.
Laying off
The final brush strokes on any surface during a painting operation. These strokes are made after the paint has been spread evenly over the surface.
Laylight
A window fixed horizontally in a ceiling to admit light (natural or artificial).
Lead paint
Usually refers to a paint based on white lead or red lead but more widely can mean any paint containing a lead pigment.
Leafing
Certain metallic pigments such as aluminium in the form of thin, flat flakes (as distinct from the granular form) which float to the surface of a paint coating and slightly overlap each other, forming a 'barrier' to help prevent staining from previous coatings or substrate.
Legged and braced door
A door formed of boards fixed to a frame with diagonal bracing pieces.
Let down
To dilute a material usually to improve application properties.
Levelling
The ability of a coating to form a smooth film without brush marks appearing.
Lifting
The softening and disturbing of an existing coat of paint when a further coat is applied over it and usually causing a wrinkled effect to develop.
Light
Any glazed opening, window, etc. is termed a light.
Light fastness
The degree of resistance to colour fading of pigments in paint on exposure to light.
Limewash
A white or pale coloured coating for brickwork, stucco, cob, walls, etc. which is made from freshly slaked quicklime to which a binding agent such as tallow has been stirred in while still hot. Pale colours are obtained by tinting with lime-fast dry pigment.
Lining paper
A plain 'wallpaper' for use as a ground for painting or wall hangings. Usually white or creamy white in colour and generally used for high quality work and to disguise surface defects in plaster which cannot be overcome by normal preparation.
Linseed oil
An oil obtained by crushing flax seed. Its drying properties make it suitable as a paint medium but it is now used mainly for modifying synthetic resins.
Live edge
During the process of painting large areas some edges of the wet paint will have to be left for a period while the remainder of the work is brought level. If these edges are still capable of being joined without a lap showing they are said to be 'live'. The art of the painter is to coat the whole surface keeping any such edges 'alive' so that the finished work shows no joints or laps.
Lock rail
The horizontal member or rail of a door in which the lock or latch is fixed.
Long oil
Term used to denote the properties of oil and resin in a vanish. A long oil varnish should contain not less than 70% drying oil. Terms for other proportions: short oil for 45-50% drying oil; medium oil for 50-70% drying oil.
Luminous paint
A paint containing a phosphorescent pigment which glows in the dark after exposure to light.
Lunette
Properly a small vault in a larger vault, but commonly used to describe a semi-circular panel or light.
Lustre
A term used to describe a particular degree of gloss, e.g. an eggshell or low gloss finish.