Conservation Glossary...

Acid-free paper addresses the problem of preserving documents. Active acid pulps eliminated also Lignin and sulphur free.

An Italian phrase meaning solely in wet in wet and usually (but not necessarily) at a single sitting. It is used most commonly with reference to oil painting.

A synthetic adhesive used in conservation.

A discoloration appearing on the surface. It may be caused by water or solvent penetration. The term may be applied to lacquer when it becomes partially opaque or cloudy.

A blueish fluorescent and opaque coating which forms on the surface of some films.

A radical deformation of a surface, resulting in the potential delamination of surface layers.

To polish something using a tool with a hard surface.

A durable cloth made from a variety of natural fibres, most commonly cotton, flax or hemp. Commonly used as the primary support for easel paintings not executed on panels.

A name associated with industrial painting. A transparent ‘coat’ more commonly called varnishing.

The strengthening of one material with another. Often used when referring to the repair of paint that is delaminating from the underlying layers. The materials used in this process are referred to as “consolidants” such as lining.

Sometimes called student quality because it will not have as much versatility as linen canvas (true canvas).

A pattern of cracks that develops on the surface of a painting as a result of the natural drying and ageing of the paint film. Aspect of the age of a painting can be determined from this.

Fine lines or minute surface cracks occurring on painted surfaces due to unequal contraction in drying or cooling.

Areas of delaminating paint that have raised edges forming small dish-like deformations across a painting’s surface.

A painting that has been lined may at some point in the future require lining again. before this the first lining (canvas) must removed = the process of delining.

Tree-ring dating-used for analysis with age of panel paintings.

Using a new canvas as an addition support between the painting and the stretcher with out any adhesion materiel involved.

Egg (either whole, yolk or white) can be used as a pigment binder. Tempera painting was very popular until the late-15th Century.

A suspension of fine particles or globules of a liquid within a liquid.

Historically, enamel has described decorative and protective glassy coatings on metal as well as glassy, decorative coatings on glass. Enamel has also implied certain organic coating such as paints or lacquers.

An artistic technique whereby drawn lines are shortened to give the illusion of depth.

Brown or grayish marks appearing on paper. The causes of foxing are not clear.

A painting executed on plaster, often as an architectural decorative scheme. See also Buon Fresco and Fresco secco.

A phrase used to describe a pigment’s impermanence and tendency to fade or change colour under the influence of natural effects such as sunlight. See also Colour permanence.

Traditionally a lean layer of size and chalk mixture to form the layer on which to paint.

The application of gold leaf to a prepared surface. When applied to a water-based gesso (e.g. a picture frame) the technique is referred to as “water gilding”. If the surface is prepared with an oil-rich medium, it is referred to as “oil gilding”. Oil gilding gives a more durable surface, but cannot be burnished as well as a water gilded one.

An almost transparent paint on top of body colour. (Or other previous paint).

Transparent vanish. Conservators deal with the challenge of painting being too glossy.

A layer of opaque paint applied to a support to provide a suitable colour and texture on which to draw or paint.

Undulations in a paint film caused by application of thick paint strokes.

Paint applied over losses only. This is a technique commonly used by Conservators to unify a painting that has suffered paint loss. More commonly called retouching.

A small wooden wedge that fits into slots cut into the inside corners of a Stretcher to facilitate an increase in the tension of the structure. Also called a wedge.

To increases tension in a stretcher by movement with the ‘key’ or ‘wedge’.

A kit-kat or kit-cat portrait is a particular size of portrait, less than half-length, but including the hands. The name originates from a famous series of portraits which were commissioned from Godfrey Kneller for members of the Kit-Cat Club, a Whig dining club, to be hung in their meeting place at Barn Elms.

Attaching a painting directly on a new support. A painting on a canvas is attached to a new canvas = One canvas is attached to another.

The most popular drying oil used as a paint medium. The medium hardens over several weeks as components of the oil polymerise and form an insoluble matrix. Driers can be used to accelerate this process.

The gloss of a finish.

The component of a paint in which pigment is dispersed such as oil, acrylic, tempera, etc.

Organic surfaces exposed to high temperature/humidity atmospheres are attacked by fungus growth. This dark discolouration is usually a mould-type of fungus, but is more commonly called “mildew”.

A film defect associated with spraying. Appears circular imperfections sometimes referred to as the “orange peel” effect. See also orange peel.

Impervious to light, or not translucent.

An undesirable effect in a coating resulting from fast temperature change = Like orange peel.

Derived from the Italian “pentirsi” meaning “repentance.” Pentimenti are the changes in composition which a painter makes while producing a painting. These compositions are often visible in infrared images, x-rays and sometimes the naked eye.

A finely divided, insoluble substance which imparts colour to the material to which it is added.

A large molecule formed when many molecules are linked together by polymerisation.

The application of sizes and/or grounds to a support, to prepare the painting’s surface, modify it’s absorbency, texture and colour.

Illuminating a painting from a shallow angle. Surface deformations are often easier to see in raking light, as the low angle causes shadows to form behind any raised area.

Lining a painting again following de-lining.

A term used for in-painting. The aspiration of the restorer is to paint ‘in’ the missing area exclusively. Retouching is a confusing term as nothing is being ‘re’ done !

When a canvas becomes slack the corners can form a ‘wave’ like shape of converse and convex ‘rucks’.

Purity of intensity of colour. Degree of freedom from grayness.

A stretcher but with fixed corners. It cannot be expanded to tension the canvas.

A rigid wooden frame over which a canvas is usually stretched. The stretcher can be expanded by tapping keys (wedges) inserted at the corners.

Vertical or horizontal impressions visible on the surface of a painting, caused by a slack canvas coming into contact with it’s stretcher.

The physical structure that carries the paint and preparation layers. Supports can be made from almost any material, but are usually canvas, paper or wood.

A small pin with dome head used for attaching a canvas to a stretcher or strainer. (The tack predates the staple gun)

The tack is placed on to the ‘turn over’ edge to fix the canvas to a stretcher or strainer.

Usually refers to an egg (either whole, yolk or white) used as the medium, but can also refer to glue size.

From the French, meaning “to trick the eye”. An artistic style used to give an appearance of three-dimensions. Often (but not exclusively) used when referring to Frescos.

The ‘edge’ of the stretcher or strainer between the front and back (of the picture).

The light rays which are outside of the visible spectrum at it’s violet end. It is used in picture conservation to investigate added overpaint on paintings.

The clear surface to act as a ‘widow’ onto the pigments in a painting. Also called ‘Coating’.

Air and heat used to attach canvases together (lining) when a ‘panelled out’ look is required to be restored to a painting (for what ever reason).

Popular with conservators for the recipe of coating. (Wax and Varnish). A very important ingredient to give art work the right ‘age’ look.

When lining is noticeable in the original surface (conservators try to avoid this look if possible).

Also called ‘Keys’. The wedge is used to key out the stretcher when more tension is required.