Painting Conservation & Restoration Gallery
Abrasion - paint loss caused by excess friction during improper removal of varnish, over cleaning or by other types of friction.
Acrylic - a type of paint based on a family of synthetic resins made by polymerizing esters ofacrylic acids.
Ageing cracks - age cracks caused by environment and mechanical and other stresses that appear in all older paintings and can run through all the layers of a painting.
Alkyd - a synthetic resin which is a condensation product of a polybasic acid such as ophthalmic, a polyhydric alcohol such as glycerin and an oil fatty acid.
Alla prima - an Italian phrase referring to oil painting, meaning painted wet in wet, usually in a single sitting.
Binder - the film forming ingredient that binds the pigment together(linseed oil in oil painting gum arabic in watercolor paint, etc.).
Blending - blending is most commonly used with reference to academic painting to mean the blending together of separate touches of color for half tones until the gradation of tones and brush marks are imperceptible.
Blistering - separation due to heat (burn blister).
Blocking-in - referring to the broad application of masses of light, shade and color in the early stages of painting.
Bloom - a florescent bluish area that forms on the surface of varnishes, mainly caused by too much moisture in the air while the varnish is drying.
Body - the common term for the viscosity of a paint or varnish giving a quantitative description Of the consistency.
Buffer solution - a solution of a week acid (acidic acid) and a neutral salt of the same acid (sodium acetate) that way if an alkali or acid is added, the pH value does not change appreciably.
Chalking - the upper layers of the paint film become powdery after exposure to the elements.
Cleavage - of various layers of a painting ground, paint layer, varnish) as a result of particular internal and external influences.
Chiaroscuro - use of gradation of light and dark to describe forms in painting and drawing.
Computer tomography - a procedure whereby thin layers of the object under investigation are x-rayed in succession; the results are computer processed and can be displayed as a quasi three dimensional image on a screen.
Condition report - a report on the condition of the of the art work prior to and after restoration which includes any conservation and restoration procedures performed.
Conservation - to keep a painting in a condition of high quality so that it looks as it should and will resist physical change and damage. This prevents the need for restoration.
Copal - a resinous exudate dug up as a fossil and made into a varnish and a drier.
Cradle (cradling) - a structure of strips of wood fixed to the back of a wooden panel support as a measure to strengthen and help prevent warping of the panel.
Craquelure - 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.
Crawling - the tendency of a liquid to draw up and bead on the surface.
Creepage - if a freezing point of a binding agent is in the region of room temperature, it remains sticky and can in certain circumstances, creep.
Crocking - the areas where color has been removed by abrasion.
Cupping - in the course of time, every picture layer an develop flaking as a result of age cracks. Cupping is when the edges of these flakes turn upwards to form small cups.
Dammar - a colorless pale yellow resin obtained in southeast Asia from trees of the Dipterocarpaceae family and next to mastic, it is the most important natural resin for the production of varnish.
Downward pressure table - an airtight metal table with a hollow interior, the upper surface perforated with numerous small holes where the picture can be sucked to the surface by using vacuum pressure.
Drier - any catalytic material which when added to a drying oil, accelerates drying or hardening of the paint film (Japan drier).
Drying cracks - cracks that occur during the drying process of the paint layers especially when under layers dry fats than upper layers.
Drying oil - an oil which has the property of forming a solid, elastic surface when exposed to air in thin layers (linseed, poppy or walnut oils).
Efflorescence - the formation of whitish crystals formed on a painted surface, usually sodium salts which have diffused through the paint film from the substrate.
Egg tempera - egg yolk or the whole egg can be used as a pigment binder which was very popular until the advent of oil paint in the Renaissance during the late fifteenth century.
Emulsion - a suspension of fine particles of liquid within a liquid.
Extender - a filler that when mixed with the paint, which may extend the length of painting time,Alter the gloss or reinforce the film.
Facing - partial or total covering of the front of the painting with fine linen or Japan paper to protect it.
Fly specks - the bodily waste of flies that can be cleaned off with a moistened cotton swab when it is fresh but eats into the paint if old and cannot be removed.
Fugitive pigment - a phrase used to describe a pigment s impermanence and tendency to fade or change color under the effects of natural effects of light and pollution.
Gesso - traditionally, a layer of size and chalk to form a ground on which to paint.
Glair - another name for egg white which is used in egg tempera and as a coating material.
Glass transition temperature - the temperature at which natural or synthetic resins change from fluid or viscous state to a pliable or solid one.
Glaze
- a layer of transparent pigment and excess medium used over under painting to build up depth.
- a glass-like surface.
Gloss - the shine or luster of the surface coating.
Gouache - opaque water color.
Grime - dirt consisting airborne grease, soot, nicotine, etc.
Ground - an opaque layer such as gesso, which is applied to a support to provide an appropriate surface on which to paint.
Haze - the dullness of a surface resulting from faulty solvent balance or incompatibility of ingredients.
Heat vacuum table - a heated plate with a suction device and an electric heating element. The low pressure between the covering film and the heated plate is produced by a vacuum pump and controlled by a manometer.
Impasto - a texture created in a paint surface by a brush or palate knife which can be thick or delicate textures found in smoother paint surfaces.
Infrared reflectography - a procedure using infrared radiation to render visible on a screen preliminary drawings and similar subsequently painted over.
Inpainting - paint applied over losses ONLY by a conservator or restorer.
Isolating varnish - a layer of retouch varnish that isolates the final varnish from the paint surface, making it easier to remove at a future date.
Lake - a colored natural or synthetic dye absorbed into a semi-transparent base and used as a pigment.
Lifting - layer separation involving the lifting of the paint surface
Lightfast - the permanency of a pigment.
Linen - the fabric traditionally used as a support for oil painting.
Lining - also called relining, it refers to gluing a piece of cloth (occasionally two or three) to the back of an original painting on canvas as a strengthening measure.
Linseed - a type of oil most commonly used in oil painting.
Luster - the gloss of a finish.
Medium - the type of binder used in painting.
Mildew - a fungus growth caused by a high temperature humid atmosphere which causes a dark discoloration.
Mottling - a film defect associated with spraying and appears as circular imperfections.
Natural varnish - varnishes made from tree resins (dammar and mastic), fossil resins (amber and copal) and insect secretions (shellac).
Neutral retouching - retouching in which the missing paint areas are painted in a neutral tone matching the original surroundings. This is used a lot in recent years by museums.
Opacity - the hiding power of paint.
Orange peel - a pebbled film surface similar in appearance to the skin of an orange caused by rapid drying before leveling takes place.
Over-painting - bad restoration that covers not only the losses but covers original paint.
Panel - a rigid support for painting, usually wood.
Patina - in painting, this refers to a yellowish varnish.
Pentimento - a word derived from the Italian meaning repentance and refers to the changes in composition made by the artist while producing the painting.
Pigment - the mineral or organic source for the color in paint which is ground and mixed with the binder.
Polar solvents - solvents which contain oxygen and have high dielctric constants (alcohols and ketones).
Polymer - a large molecule formed by many molecules linked together by polymerization.
Poppy - after linseed oil, it is the most commonly used oil in painting.
Powdering - when the binding layer in a color layer is destroyed whether chemically, physically or mechanically, the grains of pigment come loose in the form of powder.
Primer - a layer of paint put on a canvas after it has been sized.
Raking light - illumination from the side at a low angle, thus throwing long shadows and is used in conservation and restoration photography to show up surface - re-lining - see lining irregularities such as lifting.
Re-lining - see lining irregularities such as lifting.
Resin - an organic polymer in the form of a crystalline or amorphous solid or viscous liquid which could be natural or synthetic.
Restoration - repairing of damage to a piece of artwork to make it look as close to its original condition as possible.
Retouching - the work done by a conservator or restorer to replace areas of loss or damage to a painting.
Ridge - type of layer separation involving ridged raising of the paint surface.
Sagging - the tendency of wet paint film to flow downward and become thicker on vertical surfaces.
Saturation - purity or intensity of color.
Scumble - a very thin layer of opaque or semi-opaque paint that partially covers the under layer.
Sheen - a specular reflection taken at a low angle, usually 85 degrees.
Sinking - the absorption of paint medium by a lean under layer to produce a dead or matte surface.
Size - Usually rabbit skin glue which is applied to the linen prior to gessoing.-
Strainer - a wooden frame behind a painting that has glued or nailed corners that can t be keyed out and should not be used.
Stretcher - the wooden frame behind the painting that has wooden keys in the corners to tighten the canvas.
Synthetic resin - complex amorphous organic semi-solid or solid materials built up by chemical reaction of simple molecules.
Synthetic varnish - polyvinyl acrylate.
Tempera - see egg tempera.
Thermoplastic - resins that soften and flow when heated.
Thermosteeing - resin which become hard after heating and cannot be re softened.
Total retouching - a perfect retouching only recognizable through magnification.
Tow - short lengths of linen or hemp occasionally placed over glued joints by panel makers, to secure them-
Trateggio - a retouching technique whereby the restorer, having filled the defective area, paints over with fine parallel colored stripes.
Ultraviolet - light rays which are outside the visible spectrum at its violet end and are used by the conservator to see previous restoration.
UV fluorescence microscopy - a procedure whereby preparations to be examined under the microscope are stimulated to fluoresce by intense ultraviolet radiation which enables certain substances to be distinguished.
UV varnish - a synthetic varnish that protects paintings from UVA and UVB rays.
Vacuum table - see heat vacuum table.
Vacuum envelope - a lining method whereby the two canvases are coated with adhesive and enclosed in an airtight membrane from which the air is evacuated, thus assisting the adhesion.
Varnish - an applied surface film, usually a transparent cloudless resin, natural or synthetic that provides protection for the paint.
Warp - the lengthwise threads in a piece of woven fabric.
Weft - the widthwise threads in a piece of fabric.