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. Mold Mold is a type of fungus that thrives in damp environments, feeding on organic materials such as wood, canvas, and paper. It not only causes visible surface damage, like staining and discoloration, but also weakens the structural integrity of affected materials over time. In many cases, the mold has visibly developed on several of the water-damaged works due to a recent leak. Treatment involves removing mold from the surface, drying the affected works, and applying conservation techniques to prevent further deterioration. However, while surface cleaning can mitigate visible damage, the long-term effects of mold may persist, potentially weakening the materials at a microscopic level. Complete restoration to the original state is often not possible, and ongoing care is necessary to prevent future growth. Simply put, in other words, Keep your works dry. 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. Mold Mold is a type of fungus that thrives in damp environments, feeding on organic materials such as wood, canvas, and paper. It not only causes visible surface damage, like staining and discoloration, but also weakens the structural integrity of affected materials over time. In many cases, the mold has visibly developed on several of the water-damaged works due to a recent leak. Treatment involves removing mold from the surface, drying the affected works, and applying conservation techniques to prevent further deterioration. However, while surface cleaning can mitigate visible damage, the long-term effects of mold may persist, potentially weakening the materials at a microscopic level. Complete restoration to the original state is often not possible, and ongoing care is necessary to prevent future growth. Simply put, in other words, Keep your works dry. 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.
Additional Terminology used in Art Conservation, Restoration, and Repair:
Examination, and the examination report: A visual inspection of a work of art by a trained conservator. We must consider many different surfaces on each piece of art if a written report is requested. Emailed digital photos are a good starting point, and then there will be many questions to answer before giving you an accurate explanation of the conservation or restoration work required.
Written report:Many clients initially say they'd prefer not to pay for a fine art conservation or restoration report; however, they end up asking for one in the end in most cases. It isn't easy to accurately write after the conservation or restoration work is done, when everything looks perfect following treatment.
Written condition report with conservation treatment proposal:Generally, we will offer three options in the proposal:Option one is the least expensive, and it will just stabilize the damage (rip, hole, tear, stain, etc. is still there).Option two offers some additional treatment, but the damage is usually still apparent. Option three, the work is brought back to the best it can be for viewing and future resale value. Often it looks much better than it has in its recent past. Option three is what I always prefer to do, but the client must understand that it takes skill and time to take apart and rebuild a work of art correctly. There are as many types of fine art conservation and restoration treatments as there are works of fine art.
Painting - basic traditional painting structure:From the reverse of the work, we move forward. One question I might ask is about the construction of the wall the painting is hanging on. Usually, acrylic paint on drywall or drywall covered wood plywood (in many galleries in the New York area). However, the wall could also be hard brick, soft brick, stucco, stucco-painted, real wood, real wood painted or lacquered. Is the wall an outside wall (where the otehr side is outside, or an inside ( facing another room) , a wet wall, meaning near water pipes or a water source such as a fountain. These are all questions to be considered.
The painting generally has auxilary support, such as a solid wood panel, a stretcher, or a strainer. Strainers are simple four-sided rectangles or corner triangles nailed or screwed in to lock (restrain) the support in place. A "stretcher" can expand, ideally more in one direction than the other. Traditional stretchers use small wooden wedges called "keys" tapped in to expand the rail and tighten the canvas. Each corner would have two keys, so each rail could be tapped independently as needed. Another type of stretcher is called an "expansion-bolt" stretcher. Generally, I'm not fond of these and change them out if appropriate. These have a threaded metal bolt with a round ball with holes to hand spin. The spinning "expands" the rod in both directions. Once you see the corner, it is clear that both side rails expand equally, so I don't like them. Very often, a canvas needs the stretcher needs to be keyed open more in one direction but less in the other. It is a significant consideration, and many things depend on the support to perfectly fit the canvas.
The Frame - everyone knows what a frame is; however, there are numerous questions I need to answer about the structure before I work on the painting. There are three basic types (with a plethora of variations):
1) A "Strip-Frame" is a frame in which strips of wood are nailed or screwed to the stretched painting's sides, the tacking edge. If the frame is original and vintage (made by the artist), I prefer to save it. There were four Rauschenberg paintings in a MOMA show with his original wood strip-frames from the 1950s. The works appeared in "commercial frames under glass," but inside was his original, handmade, raw-wood strip frames.
2) A "Float-Frame" is generally "L-shaped" wood (but not exclusively) and attached to the back of the work. This type of frame protects the edges of the canvas but still exposes the side edges. The gap between the canvas and the framing is often varied, caller the 'Float'. Some artists want the sides of their canvas to be visible. Some even sign theri names on the side edge. Some artists want their works framed but cannot afford it. Other paintings on canvas are not intended to be framed but needs a protective "Travel-Frame." Float-frames can be covered in glass as well.
3) A "Rabbited-frame" is a frame such as a traditional Gold leaf frame we often see around 15th to 20th-century traditional paintings. The rabbit is a wood working term, it is a Lap joint, a small shallow lap, where a piece of glass could rest with all the edges covered. I actually like this rabbit with protective glass, but then I want a space or gap of approximately 1/2 inch if air space separating the back of the glass from the surface of the painting. All too often the Rabbit of the frame is touching and pressing into the surrounding edges of the artist painting. Covering the the artist signature. I have seen it so many times in major musuems.
Support - The canvas support is the woven material which is attached to the auxiliary support. There are many types, the best of which is Flax Linen. Next in quality would be thick cotton, then polyester. Traditionally fastened to a wood stretcher with tacks along the sides (and contemporarily with staples since the 1950s.) For my work, I use copper tacks along the sides and staples on the back. I use canvas pliers to get a nice even tension and always key out my traditional stretcher for a beautiful, proper canvas stretch.
Size (or Sizing) - Used in canvas preparation (don't confuse it with the measurement or the size of a piece of paper). The size is traditionally a hide glue, or RSG (Rabbit Skin Glue), but there are other types as well. These Gelation "Hide Glue" or "Hoof Glue" or "Framers Glue" all have different characteristics from each other. One wants to measue the 'Bloom Strength' the artist canvas with the highest Bloom gelatin number the better for the repairs. Another kind of size is "Acrylic Size." You will learn that I'm not too fond of that, and as a conservator, the natural gelatin glues are best. Some people will explain that acrylic does not expand and contract like RSG, but I prefer RSG. If properly prepared and adequately applied, RSG is also thin enough to protect the linen from the oil. It works to protect the flax linen. An acrylic primer has very different chaaractistics, and but please don't paint linseed oil on acrylic.
Priming Layer - The first layer applied. For flax linen canvas material, generally the priming layer is a white oil "ground." But there are many ways to apply and coat that primer layer. It is an linseed oil with pigment. I have used lead white ground, titanium white paint ground, zinc white ground mixes, etc. There is a much to understand about canvas preparations (more on that later). Just knowing how a canvas was washed and pre-stretched before it is attached to the canvas is most important. After that, the "size" then the ground. After that, the next layer is the actual art painting.
Paint - Assuming you are using organic plant oil paint, there are generally four types of oil and various ways to make them dry fast or slow, depending on your desired technique. Raw linseed oil takes longer to dry than acrylics, but one can dry linseed oil overnight or less by pushing it. Linseed oil and other drying plant-based oil paints dry in a process called Polymerization and also Oxidation. Back to basic high school chemisty, oil molecules connect with Oxygen O2, and then the linseed oil molecules bond together and LINK to eachother in long chains, getting strogner and stronger. Petroleum based Acrylics are very different man-made synthetic resins are often very fast to dry. And using acrylics on oil might sometimes be an issue. It all depends. I will say it all depends a lot, that's why I ask so many questions for a conservation report. I have seen so much damage. There are other types of paints, including alkyds, gouache, and watercolors. If an artist uses plant based linseed oil and synthetic acrylics in the same painting, and damage occurs, when cleaning or repairs are needed, we need to know what is natural plant oil or not, as linseed oil and acrylics don't mix, and different chemicals are needed to deal with each.
Glazing - A term used to explain a painting's surface—usually, linseed oil paint where the artist has applied oil over a section. THIS TERM IS NOT THE SAME AS A VARNISH) Linseed oil, for example, to saturate that section. It is crucial to understand what one is seeing. If it is there and was put there by the artist's hand, we leave it. It likely will have darkened if it is thick, but it happens relatively early in the artwork's life, a few months even. Glazing is a technique different from varnish coating. To the artist out there who might read this, glazing with various oils mixed with pigments, or even a slight drop of turpentine, is fine. As it dries your glaze will become harder and harder over time. However, I hope you have been taught this in your reading or studies, do not add Varnish to these glazing layers. Leave the varnish out of the glaze/blending layers. Things are going on in your painting, OIL is drying with colored pigments, wonderful, make sure it dries as long as possible, I would hope two years before you add a varnish. (Frankly, I personnally prefer natural resin these are called spirit vanishes. They really look fabulous. They are mixed in solvents, and are removed in solvents. And here is the very important thing to know, if you or your artist adds any varnish to the glazing layer, or paint with oil and acrylics, the paint cleaning will be very hard to do. The solvents cleaning can take off the varnish, but also take off the bad glazing, or worse "skin" the art paint surface. And acrylic grounds or oil on top of acrylic paint, those who use both, and that also VARNISH their painting surface...one should consider the future.
"Glazing" - also refers to the use of glass, acrylic, or plexiglass to frame or cover artwork. Glass protects paintings from UV damage and light fading. While modern plexiglass acrylics have improved, I have observed instances of cracking and damage to art, as well as melting in fires. Although glass can break, double-pane glass offers the advantage of holding together without shattering. Whenever possible, I prefer to upgrade my clients’ artwork to double-pane UV non-glare, non-reflective glass for optimal protection."
Varnish - Varnishing is such a fantastic and dynamic event in the life of a painting. The subject is vast; types of varnish, application of varnish, time of varnish, etc. Too much to list here.
Written report:Many clients initially say they'd prefer not to pay for a fine art conservation or restoration report; however, they end up asking for one in the end in most cases. It isn't easy to accurately write after the conservation or restoration work is done, when everything looks perfect following treatment.
Written condition report with conservation treatment proposal:Generally, we will offer three options in the proposal:Option one is the least expensive, and it will just stabilize the damage (rip, hole, tear, stain, etc. is still there).Option two offers some additional treatment, but the damage is usually still apparent. Option three, the work is brought back to the best it can be for viewing and future resale value. Often it looks much better than it has in its recent past. Option three is what I always prefer to do, but the client must understand that it takes skill and time to take apart and rebuild a work of art correctly. There are as many types of fine art conservation and restoration treatments as there are works of fine art.
Painting - basic traditional painting structure:From the reverse of the work, we move forward. One question I might ask is about the construction of the wall the painting is hanging on. Usually, acrylic paint on drywall or drywall covered wood plywood (in many galleries in the New York area). However, the wall could also be hard brick, soft brick, stucco, stucco-painted, real wood, real wood painted or lacquered. Is the wall an outside wall (where the otehr side is outside, or an inside ( facing another room) , a wet wall, meaning near water pipes or a water source such as a fountain. These are all questions to be considered.
The painting generally has auxilary support, such as a solid wood panel, a stretcher, or a strainer. Strainers are simple four-sided rectangles or corner triangles nailed or screwed in to lock (restrain) the support in place. A "stretcher" can expand, ideally more in one direction than the other. Traditional stretchers use small wooden wedges called "keys" tapped in to expand the rail and tighten the canvas. Each corner would have two keys, so each rail could be tapped independently as needed. Another type of stretcher is called an "expansion-bolt" stretcher. Generally, I'm not fond of these and change them out if appropriate. These have a threaded metal bolt with a round ball with holes to hand spin. The spinning "expands" the rod in both directions. Once you see the corner, it is clear that both side rails expand equally, so I don't like them. Very often, a canvas needs the stretcher needs to be keyed open more in one direction but less in the other. It is a significant consideration, and many things depend on the support to perfectly fit the canvas.
The Frame - everyone knows what a frame is; however, there are numerous questions I need to answer about the structure before I work on the painting. There are three basic types (with a plethora of variations):
1) A "Strip-Frame" is a frame in which strips of wood are nailed or screwed to the stretched painting's sides, the tacking edge. If the frame is original and vintage (made by the artist), I prefer to save it. There were four Rauschenberg paintings in a MOMA show with his original wood strip-frames from the 1950s. The works appeared in "commercial frames under glass," but inside was his original, handmade, raw-wood strip frames.
2) A "Float-Frame" is generally "L-shaped" wood (but not exclusively) and attached to the back of the work. This type of frame protects the edges of the canvas but still exposes the side edges. The gap between the canvas and the framing is often varied, caller the 'Float'. Some artists want the sides of their canvas to be visible. Some even sign theri names on the side edge. Some artists want their works framed but cannot afford it. Other paintings on canvas are not intended to be framed but needs a protective "Travel-Frame." Float-frames can be covered in glass as well.
3) A "Rabbited-frame" is a frame such as a traditional Gold leaf frame we often see around 15th to 20th-century traditional paintings. The rabbit is a wood working term, it is a Lap joint, a small shallow lap, where a piece of glass could rest with all the edges covered. I actually like this rabbit with protective glass, but then I want a space or gap of approximately 1/2 inch if air space separating the back of the glass from the surface of the painting. All too often the Rabbit of the frame is touching and pressing into the surrounding edges of the artist painting. Covering the the artist signature. I have seen it so many times in major musuems.
Support - The canvas support is the woven material which is attached to the auxiliary support. There are many types, the best of which is Flax Linen. Next in quality would be thick cotton, then polyester. Traditionally fastened to a wood stretcher with tacks along the sides (and contemporarily with staples since the 1950s.) For my work, I use copper tacks along the sides and staples on the back. I use canvas pliers to get a nice even tension and always key out my traditional stretcher for a beautiful, proper canvas stretch.
Size (or Sizing) - Used in canvas preparation (don't confuse it with the measurement or the size of a piece of paper). The size is traditionally a hide glue, or RSG (Rabbit Skin Glue), but there are other types as well. These Gelation "Hide Glue" or "Hoof Glue" or "Framers Glue" all have different characteristics from each other. One wants to measue the 'Bloom Strength' the artist canvas with the highest Bloom gelatin number the better for the repairs. Another kind of size is "Acrylic Size." You will learn that I'm not too fond of that, and as a conservator, the natural gelatin glues are best. Some people will explain that acrylic does not expand and contract like RSG, but I prefer RSG. If properly prepared and adequately applied, RSG is also thin enough to protect the linen from the oil. It works to protect the flax linen. An acrylic primer has very different chaaractistics, and but please don't paint linseed oil on acrylic.
Priming Layer - The first layer applied. For flax linen canvas material, generally the priming layer is a white oil "ground." But there are many ways to apply and coat that primer layer. It is an linseed oil with pigment. I have used lead white ground, titanium white paint ground, zinc white ground mixes, etc. There is a much to understand about canvas preparations (more on that later). Just knowing how a canvas was washed and pre-stretched before it is attached to the canvas is most important. After that, the "size" then the ground. After that, the next layer is the actual art painting.
Paint - Assuming you are using organic plant oil paint, there are generally four types of oil and various ways to make them dry fast or slow, depending on your desired technique. Raw linseed oil takes longer to dry than acrylics, but one can dry linseed oil overnight or less by pushing it. Linseed oil and other drying plant-based oil paints dry in a process called Polymerization and also Oxidation. Back to basic high school chemisty, oil molecules connect with Oxygen O2, and then the linseed oil molecules bond together and LINK to eachother in long chains, getting strogner and stronger. Petroleum based Acrylics are very different man-made synthetic resins are often very fast to dry. And using acrylics on oil might sometimes be an issue. It all depends. I will say it all depends a lot, that's why I ask so many questions for a conservation report. I have seen so much damage. There are other types of paints, including alkyds, gouache, and watercolors. If an artist uses plant based linseed oil and synthetic acrylics in the same painting, and damage occurs, when cleaning or repairs are needed, we need to know what is natural plant oil or not, as linseed oil and acrylics don't mix, and different chemicals are needed to deal with each.
Glazing - A term used to explain a painting's surface—usually, linseed oil paint where the artist has applied oil over a section. THIS TERM IS NOT THE SAME AS A VARNISH) Linseed oil, for example, to saturate that section. It is crucial to understand what one is seeing. If it is there and was put there by the artist's hand, we leave it. It likely will have darkened if it is thick, but it happens relatively early in the artwork's life, a few months even. Glazing is a technique different from varnish coating. To the artist out there who might read this, glazing with various oils mixed with pigments, or even a slight drop of turpentine, is fine. As it dries your glaze will become harder and harder over time. However, I hope you have been taught this in your reading or studies, do not add Varnish to these glazing layers. Leave the varnish out of the glaze/blending layers. Things are going on in your painting, OIL is drying with colored pigments, wonderful, make sure it dries as long as possible, I would hope two years before you add a varnish. (Frankly, I personnally prefer natural resin these are called spirit vanishes. They really look fabulous. They are mixed in solvents, and are removed in solvents. And here is the very important thing to know, if you or your artist adds any varnish to the glazing layer, or paint with oil and acrylics, the paint cleaning will be very hard to do. The solvents cleaning can take off the varnish, but also take off the bad glazing, or worse "skin" the art paint surface. And acrylic grounds or oil on top of acrylic paint, those who use both, and that also VARNISH their painting surface...one should consider the future.
"Glazing" - also refers to the use of glass, acrylic, or plexiglass to frame or cover artwork. Glass protects paintings from UV damage and light fading. While modern plexiglass acrylics have improved, I have observed instances of cracking and damage to art, as well as melting in fires. Although glass can break, double-pane glass offers the advantage of holding together without shattering. Whenever possible, I prefer to upgrade my clients’ artwork to double-pane UV non-glare, non-reflective glass for optimal protection."
Varnish - Varnishing is such a fantastic and dynamic event in the life of a painting. The subject is vast; types of varnish, application of varnish, time of varnish, etc. Too much to list here.