Glossary of Fine Art Conservation & Art Restoration Terms
This list will help you understand some of the terminologies you will find in your fine art conservation or restoration condition report.
AbrasionAny changes to the surface preparation, ground, or paint due to rubbing, scraping, or cleaning with an abrasive.
Absorption1) Absorption of one substance into another through osmosis, solvent, or capillary action.2) Absorption of light, and weakening in a layer of pigment, for example.
AccretionUnintentional deposits of "foreign" material that are not part of the original painting, (for example, flyspecks, dust, dried liquids, etc.)
AdsorptionAdhesion, by physical or chemical force, of molecules of liquids or gases to the surfaces of solids and liquids, in which they come in contact.
Aging/CracksCracks due to aging, caused by mechanical or environmental and other stresses over time, often occur in all older artwork. Damage may run through every layer of a painting, originating with the support of the artwork.
Auxiliary Support Generally, referring to a stretcher or a strainer. Auxiliary support is the secondary structure of a painting or other work of art. A framework upon which one stretches a canvas.
Backing Board Stiff "backing board" is attached to the back of the auxiliary support to protect and support or frame the painting.
Beva 371Beva 371 is a specifically formulated adhesive for art conservation professionals. It has numerous uses, such as; mounting canvas to wood, textile to textile, paper to canvas, etc. Applied by roller, brush, or thinned and sprayed. It is fully reversible by heat or solvents.
BinderA material that forms a film, holding together the particles of pigments in paints (such as vegetable gum in watercolor paints or oil in oil paints.
Binding Agent/MaterialA general term for a material or product that binds together different or similar substances. Linseed or other oil, for example, which binds pigments and forms the pigment layer. When adhering materials together or gluing, we would call it a bonding agent.
BlanchingBlanching refers to the loss of contact between the binding agent and the pigment grains. Blanching alters the refraction of light in the layer, resulting in discoloration. It is generally caused by exposure of the surface to humidity and condensation.
BlisteringBlistering is the separation of layers due to heat (AKA burn blister).
BloomA yellowish, white, or bluish-white haze on the surface, caused by ground and paint components migrating to the painting's surface.
BucklingLifting off of the ground and paint layers that form ridges. Caused by compression (pressure), it is associated with flaking, cleavage, and cracks.
CanvasFabric support for a painting, generally composed of one of the following woven fibers: hemp, cotton, ramie, jute, linen, (or a mixture of these).
ChalkingDeposit of powder on a layer of paint, due to insufficient binding medium (or outdoor exposure to weather).
ChipA bit of material (wood, ground, or paint layer) broken away from the artwork.
CleavageSeparation of a layer.
CockleA bulge or pucker that creates a wrinkled or creased surface.
Concentric CracksCracks in a circular or cobweb pattern. They are usually caused by pressure or a bump into a painting.
Corner Draws Corner draws are ripples radiating from the corners of the canvas.
CraquelureA network of cracks.
Crazing1) The cracking of a layer of varnish into a network that becomes opaque.2) Crazing in the pigment/paint layer (refer to "blanching" above).
Cup (or Cupping)Over time, every painting layer will develop flaking as a result of cracks due to aging. Cupping refers to when the cracks' edges turn upwards and form what we call "cups."
DeformationChanges to the original shape of the support, including depressions, cockling, and bulges.
DentA concave indentation (deformation) on a surface, caused by pressure or a collision.
Diagonal CracksOften appearing in the corners of paintings due to inconsistent keying or being dropped on its corner.
DispersionThe fine distribution of particles from one substance in another.
Drying Cracks Occur during the drying process of paint layers. Caused by chemical processes and other physical properties, they are generally curved and wide.
Drying OilsOils used in European easel painting – poppy-seed, walnut, and linseed oil are referred to as drying oils—Oxidizing and "drying" due to exposure to oxygen.
Edge-StripA protective strip of metal, plastic, or wood attached to a painting's outer edges extending above the front surface.
EncausticA technique using pigments or paints mixed with hot wax as the medium.
ExaminationA visual inspection of a work of art.
FacingA total or partial protective covering (with Japanese paper) of a delicate painting.
Feather CracksA feather pattern of cracks caused by some contact with the back of the painting (for example, a scrape or a hammer's tap when keying.
Fill/FillingReplacing lost material, paint, or paint with ground layers, to an area of to level with the surrounding surface.
FlakingA complete or partial detachment of fragments of ground or paint layers from the layer below.
GlazeA transparent layer of oil or resin applied to the surface of a painting.
GouacheAn opaque type of watercolor.
GrimeDeposit of dirt on or ingrained into the surface of the artwork.
GroundAn opaque preparation layer (colored or white) is applied to the support material to create a painting foundation.
Heat/Vacuum TableA heated surface with an electric heating element and a suction device.
ImpastoThis technique or process of thickly applying paint, medium, or pigment makes it stand out from a surface.
ImprimaturaA layer of paint thinly applied over the ground to provide a base tone for a painting.
IndicatorA material that changes color, reacting to a chemical, indicating that a response has occurred.
Infrared ReflectographyA procedure that uses infrared radiation to make preliminary drawings and other subsequently painted over items visible.
InpaintingThe technique of adding new paint to areas where the original color is missing.
Japanese PaperGenerally refers to traditional Japanese Mulberry paper AKA "Washi." Often used in the conservation and mending of art on paper and books.
Key (or Keying)A corner key or (tightening key) is a small wedge or block of wood or plastic, tapped into a stretcher's inside corners to adjust the tension or prevent a sagging canvas.
Layer SeparationThe Separation of the layers in a painting (ground, paint layer, varnish) due to particular external and internal causes.
LiftingThe separation of one layer from another.
LinerThe inside section of a frame "lining" a painting and made independently of the frame structure.
LiningSometimes referred to as "relining," is a strengthening technique. Gluing a piece (or several pieces) of cloth to the rear of a textile support surface.
Loose LiningFabric is stretched behind, but not attached to a canvas painting, supporting and protecting the artwork.
Loss/LacunaAn area of paint or paint and ground layer, missing due to damage or deterioration.
MarouflageThe technique of adhering a canvas to a rigid material, such as a panel or wall.
Mechanical CracksCracks with sharp edges, caused by excessive stress or movement in layers of the painting.
MediumA material mixed with paint altering particular characteristics (flow, texture, drying time, or finish). See "Binder" (above)
Mending PlateA custom-shaped metal plate for holding a painting in a frame.
Nap-Bond MethodA Lining technique where the lining canvas is attached to the original canvas with an adhesive layer on only a few small areas, not covering the entire canvas.
Neutral RetouchingA type of retouching where a missing area of paint is painted with a neutral tone matching the original surroundings.
Normal RetouchingA retouching process in which the damaged section is painted in fine dots and strokes (after filling) with a color and form, making the paint layer appear uniform.
OverpaintPaint, not applied by an artist that covers part of the original painting.
Paint LayerThe paint layer (or multiple layers) that lie between the ground and the varnish.
PatinaA yellowed varnish in a painting, or changes in the paint layer over time.
PentimentoA change made by an artist to artwork, in the course of its completion.
PercussionThe examination of a picture by tapping it to detect a cavity in the ground, paint layer, or varnish.
PigmentA color-producing material, embedded in a binding agent.
Plain WeaveA pattern commonly seen in a canvas where one thread is woven alternately under and over the warp threads
PowderingIf a binding agent in the color layer is damaged (mechanically, physically, or chemically), grains of pigment may come loose in powder form.
PunctureA small tear or hole through the painting.
Raking LightIllumination at a low angle, from the side, creating long shadows. Helpful in restoration photography to show surface inconsistencies such as lifting.
Scraping An abrasion caused by repetitive contact with a sharp object or tool, resulting in removal or loss of one or more material layers.
Sight Edge The visible edge of an artwork in a frame.
Size An emulsion, gel, or solution, applied to canvas or other support material before a ground layer is applied. Size protects the canvas fibers from oils in the medium and reduces the absorbency of the fabric.
Skinning Abrasion to the original paint layers by inappropriate cleaning methods.
Strainer An additional support structure (generally made of wood) with rigid corners, upon which one would stretch a canvas.
Stretcher A support frame (usually made of wood) with adjustable expandable (keyable) corners, upon which one would stretch a canvas.
Stretcher Marks A line of cracks or deformations in the painting's surface extending along the inside edge of a stretcher or strainer bar.
Support The material upon which an artist applies a ground and paint.
Surface Dirt A deposit of dirt, grime, dust, soot, nicotine, or any other contaminants on an artwork's surface.
Tabby PatternAKA "Plain Weave" (see above)
Tacking Margin/Tacking EdgeThe perimeter section of the canvas wrapping around the support (stretcher) and is held in place by staples or tacks.
Tear Damage to paper or fabric where it has pulled apart, leaving irregular or ragged edges.
Tenting Lifting of the paint, or ground and paint layer, where they are pushed upward into a tentlike shape.
Twill Weave An intricate weave creating a diagonal pattern
UV Fluorescence MicroscopyA procedure in which we stimulate the area of examination to fluoresce with ultraviolet radiation under a microscope. This procedure enables us to distinguish particular substances.
Vacuum TableAKA Heat/Vacuum Table (see above)
Varnish A resin solution dissolved in a solvent that dries to create a transparent film—generally used for a final surface coating. Mainly used to saturate the colors, protect the paint, and even out the glossiness.
Wear Changes to the surface of artwork due to the effect of abrasion.
Wetting agentA synthetic or natural liquid which reduces the surface tension of water or other liquids. A wetting agent enables them to penetrate cavities in a damaged paint layer, for example.
WrinklesFurrows, ridges, or puckers that occur in a paint or varnish film during the drying process.
Absorption1) Absorption of one substance into another through osmosis, solvent, or capillary action.2) Absorption of light, and weakening in a layer of pigment, for example.
AccretionUnintentional deposits of "foreign" material that are not part of the original painting, (for example, flyspecks, dust, dried liquids, etc.)
AdsorptionAdhesion, by physical or chemical force, of molecules of liquids or gases to the surfaces of solids and liquids, in which they come in contact.
Aging/CracksCracks due to aging, caused by mechanical or environmental and other stresses over time, often occur in all older artwork. Damage may run through every layer of a painting, originating with the support of the artwork.
Auxiliary Support Generally, referring to a stretcher or a strainer. Auxiliary support is the secondary structure of a painting or other work of art. A framework upon which one stretches a canvas.
Backing Board Stiff "backing board" is attached to the back of the auxiliary support to protect and support or frame the painting.
Beva 371Beva 371 is a specifically formulated adhesive for art conservation professionals. It has numerous uses, such as; mounting canvas to wood, textile to textile, paper to canvas, etc. Applied by roller, brush, or thinned and sprayed. It is fully reversible by heat or solvents.
BinderA material that forms a film, holding together the particles of pigments in paints (such as vegetable gum in watercolor paints or oil in oil paints.
Binding Agent/MaterialA general term for a material or product that binds together different or similar substances. Linseed or other oil, for example, which binds pigments and forms the pigment layer. When adhering materials together or gluing, we would call it a bonding agent.
BlanchingBlanching refers to the loss of contact between the binding agent and the pigment grains. Blanching alters the refraction of light in the layer, resulting in discoloration. It is generally caused by exposure of the surface to humidity and condensation.
BlisteringBlistering is the separation of layers due to heat (AKA burn blister).
BloomA yellowish, white, or bluish-white haze on the surface, caused by ground and paint components migrating to the painting's surface.
BucklingLifting off of the ground and paint layers that form ridges. Caused by compression (pressure), it is associated with flaking, cleavage, and cracks.
CanvasFabric support for a painting, generally composed of one of the following woven fibers: hemp, cotton, ramie, jute, linen, (or a mixture of these).
ChalkingDeposit of powder on a layer of paint, due to insufficient binding medium (or outdoor exposure to weather).
ChipA bit of material (wood, ground, or paint layer) broken away from the artwork.
CleavageSeparation of a layer.
CockleA bulge or pucker that creates a wrinkled or creased surface.
Concentric CracksCracks in a circular or cobweb pattern. They are usually caused by pressure or a bump into a painting.
Corner Draws Corner draws are ripples radiating from the corners of the canvas.
CraquelureA network of cracks.
Crazing1) The cracking of a layer of varnish into a network that becomes opaque.2) Crazing in the pigment/paint layer (refer to "blanching" above).
Cup (or Cupping)Over time, every painting layer will develop flaking as a result of cracks due to aging. Cupping refers to when the cracks' edges turn upwards and form what we call "cups."
DeformationChanges to the original shape of the support, including depressions, cockling, and bulges.
DentA concave indentation (deformation) on a surface, caused by pressure or a collision.
Diagonal CracksOften appearing in the corners of paintings due to inconsistent keying or being dropped on its corner.
DispersionThe fine distribution of particles from one substance in another.
Drying Cracks Occur during the drying process of paint layers. Caused by chemical processes and other physical properties, they are generally curved and wide.
Drying OilsOils used in European easel painting – poppy-seed, walnut, and linseed oil are referred to as drying oils—Oxidizing and "drying" due to exposure to oxygen.
Edge-StripA protective strip of metal, plastic, or wood attached to a painting's outer edges extending above the front surface.
EncausticA technique using pigments or paints mixed with hot wax as the medium.
ExaminationA visual inspection of a work of art.
FacingA total or partial protective covering (with Japanese paper) of a delicate painting.
Feather CracksA feather pattern of cracks caused by some contact with the back of the painting (for example, a scrape or a hammer's tap when keying.
Fill/FillingReplacing lost material, paint, or paint with ground layers, to an area of to level with the surrounding surface.
FlakingA complete or partial detachment of fragments of ground or paint layers from the layer below.
GlazeA transparent layer of oil or resin applied to the surface of a painting.
GouacheAn opaque type of watercolor.
GrimeDeposit of dirt on or ingrained into the surface of the artwork.
GroundAn opaque preparation layer (colored or white) is applied to the support material to create a painting foundation.
Heat/Vacuum TableA heated surface with an electric heating element and a suction device.
ImpastoThis technique or process of thickly applying paint, medium, or pigment makes it stand out from a surface.
ImprimaturaA layer of paint thinly applied over the ground to provide a base tone for a painting.
IndicatorA material that changes color, reacting to a chemical, indicating that a response has occurred.
Infrared ReflectographyA procedure that uses infrared radiation to make preliminary drawings and other subsequently painted over items visible.
InpaintingThe technique of adding new paint to areas where the original color is missing.
Japanese PaperGenerally refers to traditional Japanese Mulberry paper AKA "Washi." Often used in the conservation and mending of art on paper and books.
Key (or Keying)A corner key or (tightening key) is a small wedge or block of wood or plastic, tapped into a stretcher's inside corners to adjust the tension or prevent a sagging canvas.
Layer SeparationThe Separation of the layers in a painting (ground, paint layer, varnish) due to particular external and internal causes.
LiftingThe separation of one layer from another.
LinerThe inside section of a frame "lining" a painting and made independently of the frame structure.
LiningSometimes referred to as "relining," is a strengthening technique. Gluing a piece (or several pieces) of cloth to the rear of a textile support surface.
Loose LiningFabric is stretched behind, but not attached to a canvas painting, supporting and protecting the artwork.
Loss/LacunaAn area of paint or paint and ground layer, missing due to damage or deterioration.
MarouflageThe technique of adhering a canvas to a rigid material, such as a panel or wall.
Mechanical CracksCracks with sharp edges, caused by excessive stress or movement in layers of the painting.
MediumA material mixed with paint altering particular characteristics (flow, texture, drying time, or finish). See "Binder" (above)
Mending PlateA custom-shaped metal plate for holding a painting in a frame.
Nap-Bond MethodA Lining technique where the lining canvas is attached to the original canvas with an adhesive layer on only a few small areas, not covering the entire canvas.
Neutral RetouchingA type of retouching where a missing area of paint is painted with a neutral tone matching the original surroundings.
Normal RetouchingA retouching process in which the damaged section is painted in fine dots and strokes (after filling) with a color and form, making the paint layer appear uniform.
OverpaintPaint, not applied by an artist that covers part of the original painting.
Paint LayerThe paint layer (or multiple layers) that lie between the ground and the varnish.
PatinaA yellowed varnish in a painting, or changes in the paint layer over time.
PentimentoA change made by an artist to artwork, in the course of its completion.
PercussionThe examination of a picture by tapping it to detect a cavity in the ground, paint layer, or varnish.
PigmentA color-producing material, embedded in a binding agent.
Plain WeaveA pattern commonly seen in a canvas where one thread is woven alternately under and over the warp threads
PowderingIf a binding agent in the color layer is damaged (mechanically, physically, or chemically), grains of pigment may come loose in powder form.
PunctureA small tear or hole through the painting.
Raking LightIllumination at a low angle, from the side, creating long shadows. Helpful in restoration photography to show surface inconsistencies such as lifting.
Scraping An abrasion caused by repetitive contact with a sharp object or tool, resulting in removal or loss of one or more material layers.
Sight Edge The visible edge of an artwork in a frame.
Size An emulsion, gel, or solution, applied to canvas or other support material before a ground layer is applied. Size protects the canvas fibers from oils in the medium and reduces the absorbency of the fabric.
Skinning Abrasion to the original paint layers by inappropriate cleaning methods.
Strainer An additional support structure (generally made of wood) with rigid corners, upon which one would stretch a canvas.
Stretcher A support frame (usually made of wood) with adjustable expandable (keyable) corners, upon which one would stretch a canvas.
Stretcher Marks A line of cracks or deformations in the painting's surface extending along the inside edge of a stretcher or strainer bar.
Support The material upon which an artist applies a ground and paint.
Surface Dirt A deposit of dirt, grime, dust, soot, nicotine, or any other contaminants on an artwork's surface.
Tabby PatternAKA "Plain Weave" (see above)
Tacking Margin/Tacking EdgeThe perimeter section of the canvas wrapping around the support (stretcher) and is held in place by staples or tacks.
Tear Damage to paper or fabric where it has pulled apart, leaving irregular or ragged edges.
Tenting Lifting of the paint, or ground and paint layer, where they are pushed upward into a tentlike shape.
Twill Weave An intricate weave creating a diagonal pattern
UV Fluorescence MicroscopyA procedure in which we stimulate the area of examination to fluoresce with ultraviolet radiation under a microscope. This procedure enables us to distinguish particular substances.
Vacuum TableAKA Heat/Vacuum Table (see above)
Varnish A resin solution dissolved in a solvent that dries to create a transparent film—generally used for a final surface coating. Mainly used to saturate the colors, protect the paint, and even out the glossiness.
Wear Changes to the surface of artwork due to the effect of abrasion.
Wetting agentA synthetic or natural liquid which reduces the surface tension of water or other liquids. A wetting agent enables them to penetrate cavities in a damaged paint layer, for example.
WrinklesFurrows, ridges, or puckers that occur in a paint or varnish film during the drying process.