Wondering what your painting conservator is talking about? Here is a glossary of terms you might encounter when you have an oil painting that needs restoration.
Binder: The substance that holds pigments together in paint; common binders include linseed oil, egg tempera, or acrylic polymer.
Gesso: A mixture of chalk or gypsum and a binder, applied to a support as a ground for painting.
Ground: The preparatory layer applied to the support before painting to provide a suitable surface for the paint.
Humidity Control: Measures taken to regulate and maintain appropriate levels of humidity to prevent damage to the painting.
Inpainting: The process of carefully adding new paint to areas of loss or damage to visually integrate them with the original.
Isolation Layer: A protective layer applied between the original paint layer and a new varnish or retouching to prevent any chemical interactions.
Pigment: The colorant in paint, often a finely ground powder derived from natural or synthetic sources.
Retouching: The application of paint to restore or improve the visual appearance of an artwork, often done during conservation.
Support: The physical material on which a painting is created, such as canvas, wood panel, or metal.
Varnish: A protective coating applied to a painting’s surface to enhance colors, provide gloss, and protect against environmental factors.
Examination Phrases
Cross-Polarized Light Examination: The use of polarized light to reveal details about the painting’s surface, such as varnish layers, retouching, and cracks.
Digital Imaging: Using high-resolution photography or digital scanning to capture detailed images of the painting, aiding in the documentation and analysis of its condition.
Environmental Monitoring: Tracking and analyzing the environmental conditions surrounding the painting, including temperature, humidity, and light levels, to assess their impact on the artwork’s stability.
Gloss Measurement: Quantifying the level of gloss or sheen on the painting’s surface, which can provide insights into the condition of varnishes and protective coatings.
Infrared Reflectography (IRR): A non-invasive technique that uses infrared light to penetrate surface layers, revealing underlying sketches, underdrawings, and alterations not visible to the naked eye.
Microclimate Monitoring: Continuous monitoring of the microclimate around the painting to identify fluctuations in temperature and humidity that may affect its condition.
Microscopic Examination: Close inspection using a microscope to examine the painting at a microscopic level, revealing details such as brushwork, pigments, and the condition of the paint layers.
Painting Condition Report: Comprehensive documentation outlining the current condition of the painting, including a detailed description of damages, losses, and recommendations for conservation.
Paint Cross-Section Analysis: A sample of paint layers is taken from a specific area and examined under a microscope to analyze the stratigraphy, pigments, and binding media, providing insights into the artist’s techniques and the painting’s condition.
Pigment Analysis: Laboratory analysis of pigments using techniques like X-ray fluorescence (XRF) or Raman spectroscopy to identify the chemical composition of pigments used in the painting.
Raking Light Examination: Illuminating the painting from a low angle to highlight surface irregularities, such as cracks, impasto, or texture.
Surface Texture Analysis: Measuring the texture of the painting’s surface using tools such as profilometers to assess the level of deterioration, wear, or damage.
UV Examination: The use of ultraviolet light to reveal hidden details, retouching, or previous restoration work that may fluoresce differently from the original paint.
Visual Inspection: A thorough examination of the painting’s surface, colors, and overall appearance to identify visible issues such as cracks, discoloration, or losses.
X-radiography: The use of X-rays to create images of the painting, allowing conservators to see beneath the paint layers and identify hidden features, damages, or repairs.
Damage Terms
Abrasion: Surface damage caused by friction or rubbing, leading to the removal or disturbance of paint layers.
Blanching: The formation of a milky or cloudy appearance in varnish, often caused by moisture or other environmental factors.
Bleeding: The migration of colors or substances within the paint layers, leading to discoloration or staining.
Canvas Distortion: Changes in the shape or tension of the canvas support, leading to deformations in the paint layer.
Cracking: The development of visible cracks or fissures in the paint layers, often caused by movement in the support or environmental conditions.
Craquelure: Fine cracks that develop in the paint surface over time, often caused by the natural aging of the painting.
Cupping: The warping or bending of a support, causing the paint to form concave shapes.
Delamination: Separation or lifting of paint layers from each other or from the support.
Fading: Loss of color intensity in pigments due to exposure to light, particularly ultraviolet (UV) light.
Fire or Smoke Damage: Harm caused by exposure to fire or smoke, leading to discoloration, soot deposition, or charring of the painting.
Flaking: The detachment of small fragments or layers of paint from the underlying support, often due to environmental changes or poor adhesion.
Impact Damage: Physical harm resulting from contact with a sharp or blunt object, leading to dents, punctures, or tears in the canvas or paint.
Insect Damage: Harm caused by insects, such as beetles or moths, which may eat through or damage the canvas or paint layers.
Liquid Staining: Damage caused by exposure to liquids, leading to discoloration, swelling, or the dissolution of paint layers.
Loss or Missing Areas: Portions of the painting that are no longer present due to damage, decay, or intentional removal.
Mold/Mildew: Fungal growth on the surface of a painting, often resulting from high humidity or poor storage conditions.
Rippling: Small waves or undulations in the canvas caused by fluctuations in environmental conditions.
Stretcher Bar Damage: Warping or bending of the wooden framework on which the canvas is stretched.
Varnish Discoloration: Changes in the color of the varnish layer, often turning yellow or brown over time.
Warpage: Distortion or bending of the support, often caused by changes in humidity or temperature.
Yellowing: The gradual development of a yellow tint in the paint or varnish layers over time.
Solvents
Acetone: A strong solvent commonly used for cleaning and degreasing surfaces. It evaporates quickly, making it suitable for delicate cleaning tasks, but caution is needed as it can be harsh on certain paint types and requires careful testing.
D-Limonene: A citrus-based solvent derived from orange peel oil. It is considered environmentally friendly and is sometimes used in conservation for its mild cleaning properties.
Ethanol: An alcohol-based solvent that is sometimes used for cleaning surfaces. It evaporates quickly and is relatively mild, making it suitable for some delicate cleaning tasks.
Isopropyl Alcohol: A common household solvent that is sometimes used for cleaning oil paintings. It has a milder odour than many other solvents and is effective for removing dirt and grime.
Mineral Spirits: A petroleum-derived solvent commonly used for thinning oil-based paints and for cleaning paint brushes and palettes. It is often used in conservation for its relatively low toxicity.
Naphtha: A petroleum-based solvent with a fast evaporation rate, suitable for cleaning oil paintings. It is often used in conservation for its efficiency and minimal residue.
Methyl Ethyl Ketone (MEK): A strong, fast-evaporating solvent often used for industrial and conservation purposes. It is effective in removing certain types of contaminants but should be used with caution due to its strength.
Petroleum Ether: A low-boiling solvent distilled from petroleum. It evaporates quickly and is used in conservation for cleaning purposes.
Propylene Glycol Methyl Ether (PGME): A solvent with a slow evaporation rate, making it suitable for certain cleaning applications where a longer drying time is desired.
Turpentine: A natural solvent derived from pine trees, specifically the resin. It is commonly used in painting and restoration for thinning oil paints and cleaning brushes, though it has a stronger odour compared to mineral spirits.
Stoddard Solvent: A petroleum-based solvent with a medium evaporation rate. It is less aromatic than some other solvents and is used in conservation for cleaning purposes.
White Spirits: A petroleum-derived solvent similar to mineral spirits but with a higher boiling point. It is often used for thinning paint and cleaning brushes and can be less harsh on certain paints.
Glues
Acrylic Emulsion: A water-based adhesive made from acrylic polymers. Acrylic emulsions are commonly used in conservation for their stability, transparency, and reversible properties.
Aquazol: A synthetic resin used in conservation as a consolidant or adhesive.
Beeswax: A natural wax produced by honeybees. It is sometimes used in conservation as a component in adhesive formulations for its pliability and compatibility with paintings.
Carboxymethyl Cellulose (CMC): A cellulose derivative often used as an adhesive in conservation. It is water-soluble and valued for its stability.
EVA (Ethylene Vinyl Acetate): A copolymer of ethylene and vinyl acetate used in conservation for its adhesive properties. It is often employed in heat-activated applications.
Fish Glue: A glue derived from fish collagen, often obtained from fish swim bladders. It has been used in conservation for its reversible properties and compatibility with artworks.
Gelatin: A protein-based glue derived from animal collagen, usually obtained from the connective tissues of animals. It is used for various applications in conservation due to its reversible nature.
Gellan Gum: A natural polysaccharide derived from bacteria. It is used in conservation as an adhesive for its stability and compatibility with artworks.
Hide Glue: A glue made from animal collagen, often derived from hides or bones. It has been traditionally used in conservation for its reversible nature and compatibility with various materials.
Klucel G: A cellulose ether often used in conservation as a consolidant or adhesive. It is soluble in various solvents and is valued for its stability and reversibility.
PVA (Polyvinyl Acetate): A synthetic polymer adhesive commonly used in conservation for its stability, flexibility, and reversible qualities. It is often used for repairs and consolidations.
Methylcellulose: A water-soluble cellulose derivative used as a glue or adhesive in conservation. It is known for its non-toxic nature, reversible properties, and suitability for paper and canvas repairs.
Paraloid B-72: A thermoplastic acrylic resin often used in conservation as a consolidant or adhesive. It is known for its transparency and stability.
Polyvinyl Butyral (PVB): A synthetic resin commonly used in conservation as a film-forming adhesive.
Rabbit Skin Glue: A type of hide glue specifically made from rabbit skins. It has been historically used in the preparation of canvases and for various conservation purposes.
Varnishes
Acrylic Varnish: A varnish made from acrylic polymers. It is widely used in conservation for its clarity and UV resistance. Acrylic varnish is often available in matte, satin, and gloss finishes.
BEC (Butyl Ethyl Cellulose) Varnish: A varnish made from a cellulose derivative. It is often used in conservation for retouching.
Damar Varnish: A natural resin varnish derived from the damar tree. It is widely used in conservation for its clarity, gloss, and reversible nature. Damar varnish can yellow over time.
Laropal A-81 Varnish: A synthetic resin varnish with good chemical stability and resistance to yellowing. It is often used in conservation for its clarity and durability.
Mastic Varnish: A varnish made from mastic resin, obtained from the mastic tree. It is known for its high clarity, gloss, and resistance to yellowing. Mastic varnish is often used in fine art conservation.
MS2A (Methyl Methacrylate-2-ethylhexyl acrylate copolymer) Varnish: A synthetic resin varnish known for its clarity and resistance to yellowing.
Paraloid B-72 Varnish: A thermoplastic acrylic resin varnish known for its stability and transparency. It is commonly used in conservation and is compatible with a range of surfaces.
Polyurethane Varnish: A synthetic varnish made from polyurethane resins. It is known for its durability, resistance to abrasion, and high gloss. Polyurethane varnish may have a slight yellowing effect.
Regalrez Varnish: A synthetic resin varnish often used in conservation for its stability, clarity, and resistance to yellowing. It is suitable for both naturalistic and abstract artworks.
Shellac Varnish: A varnish derived from the secretion of the lac bug. It is commonly used in conservation but may darken over time.
Lining Techniques
Beva Lining: A lining technique using Beva 371, a heat-activated adhesive made from synthetic resins. The adhesive is applied to both the original canvas and the new lining canvas, and the two are bonded together using heat and pressure.
Full Lining: A comprehensive relining process where a new canvas is adhered to the entire back of the original canvas using an adhesive. This method is employed to provide structural support, stabilize the original canvas, and address issues like tears, weaknesses, or distortions.
Heat-Set Lining: A technique that uses heat-activated adhesives to bond the original and lining canvases together. This method allows conservators to control the level of adhesion by adjusting the heat application.
Inlay Lining: A lining technique where the conservator inserts a new canvas in areas of loss or weakness, providing localized support and stabilisation.
Partial Lining: A technique where only a portion of the painting, such as a damaged or weakened area, is lined. This is done to address specific issues without the need for a full lining.
Paste Lining: A traditional lining method where a paste adhesive is applied to the back of the original canvas, and a new lining canvas is attached. The process involves careful stretching and smoothing to ensure proper adhesion.
Poultice Lining: A lining method where a poultice, a soft mass or cloth saturated with a consolidant, is applied to the back of the original canvas. The new lining canvas is then adhered, often with the help of heat and pressure.
Stretch Lining: A technique where the original canvas is attached to the lining canvas using a stretching process. Tension is applied to both canvases to achieve adhesion without the use of adhesives.
Strip Lining: A technique where a new canvas or lining fabric is attached to the original canvas by applying an adhesive along the edges, leaving the centre unattached. This method is used to provide additional support without fully bonding the two canvases.
Vacuum Hot Table Lining: A lining method that involves placing the painting on a hot table while applying pressure through a vacuum system. Heat-activated adhesives are used to bond the canvases together, and the process is carefully monitored to achieve optimal results.
Watercolour Paper Lining: A method of lining where a strong, stable watercolor paper is adhered to the back of the original canvas using an adhesive. This approach is chosen when a traditional lining fabric may not be suitable.
Wax-Resin Lining: A lining technique that involves applying a mixture of wax and resin to the back of the original canvas. The lining canvas is then attached using heat and pressure. The wax-resin lining method aims to provide structural support while maintaining flexibility.