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Whistler Paintings and Drawings at the Art Institute of Chicago
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Glossary

  • About This Glossary

  • à grain

  • abrasion

  • absorbent ground

  • additive

  • aqueous lining

  • backscattered electron (BSE)

  • binder

  • binding medium

  • blocked

  • blocking in

  • canvas

  • canvas stamp

  • chamfer

  • color merchant

  • commercially primed

  • complementary color

  • consolidant

  • consolidate

  • cradle

  • cross section

  • cross-sectional analysis

  • crossbar

  • crosshatching

  • cusping

  • darkfield illumination

  • delamination

  • differential interference contrast (DIC) microscopy

  • drying cracks

  • edge lining

  • en plein air

  • extender

  • facture

  • figure

  • filler

  • fluorescence

  • foldover

  • Fourier transform infrared microspectroscopy (FTIR)

  • gas chromatography mass spectrometry (GCMS)

  • graphite

  • ground

  • haute

  • ICA spring stretcher

  • imitation or simulated deckle edge

  • impasto

  • impressed watermark

  • infrared reflectogram

  • infrared reflectography

  • inpainted

  • inpainting

  • IRR

  • keying out

  • keys

  • laid in

  • lake pigment

  • lay-in

  • laying in

  • lined

  • lining

  • lisse

  • marine

  • metal soap formation

  • millboard

  • miter

  • modeling

  • natural-resin varnish

  • oil

  • overpaint

  • painting knife

  • palette

  • palette knife

  • panel

  • paysage

  • pentimento (pl. pentimenti)

  • pentimenti

  • photomicrograph

  • picture plane

  • pigment

  • plain weave

  • plein air

  • pochade box

  • pre-primed

  • preparatory layer

  • primed

  • priming

  • radio opaque

  • radio transparent

  • raking light

  • Raman microspectroscopy

  • rebate

  • repaint

  • retouching

  • scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX)

  • scanning macro X-ray fluorescence spectroscopy (macro-XRF)

  • selvage

  • sinking in

  • size

  • standard-size supports

  • standard format

  • stretcher

  • stumping

  • support

  • surface-enhanced Raman spectroscopy (SERS)

  • synthetic varnish

  • tacking edge

  • tacking margin

  • thread count

  • tonal

  • tonality

  • tone

  • toned

  • toning layer

  • tooth

  • transfer paper

  • transmitted-infrared imaging

  • transmitted-light imaging

  • ultraviolet (UV)

  • underdrawing

  • underpainting

  • unvarnished

  • varnish

  • varnishing

  • warp thread

  • wash

  • watermark

  • wax-resin lining

  • weave

  • weft thread

  • wet-in-wet

  • wet-on-wet

  • wet-over-dry

  • wove paper

  • X-radiography

  • X-ray

  • X-ray fluorescence spectroscopy (XRF)

  • BIBLIOGRAPHIC REFERENCES

  • Catalogues

  • C

  • K

  • M

  • YMSM

  • L

  • Institutions

  • HAG

  • LC

  • Literature

  • GUW

  • Andrew Young et al.

  • Levy

  • MacDonald (1995)

  • MacDonald and Petri

  • Way

  • About This Glossary

    • Several sources were particularly helpful in compiling this glossary: American Institute for Conservation of Historic and Artistic Works, Painting Conservation Catalog, vol. 2, Stretchers and Strainers (Paintings Specialty Group of the AIC, 2008); Nancy Ash, Scott Homolka, and Stephanie Lussier, Descriptive Terminology for Works of Art on Paper: Guidelines for the Accurate and Consistent Description of the Materials and Techniques of Drawings, Prints, and Collages, with Rebecca Pollak and Eliza Spaulding, ed. Renée Wolcott (Philadelphia Museum of Art, 2014), http://www.philamuseum.org/doc_downloads/conservation/DescriptiveTerminologyforArtonPaper.pdf; David Bomford, Jo Kirby, John Leighton, and Ashok Roy, Art in the Making: Impressionism, exh. cat. (National Gallery, London/Yale University Press, 1990); Anthea Callen, The Art of Impressionism: Painting Technique and the Making of Modernity (Yale University Press, 2000); Anthea Callen, Techniques of the Impressionists (New Burlington Books, 1982); Canadian Conservation Institute, Condition Reporting: Paintings, vol. 3, Glossary of Terms (Government of Canada, 1994), https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/condition-reporting-paintings-glossary.html; Anne F. Clapp, Curatorial Care of Works of Art on Paper (Lyons & Bueford, 1987); Francis W. Dolloff and Roy L. Perkinson, How to Care for Works of Art on Paper (Museum of Fine Arts, Boston, 1985); E. J. Labarre, Dictionary and Encyclopedia of Paper and Paper-Making, 2nd ed. (Swets & Zeitlinger, 1952); Ralph Mayer, The Artist’s Handbook of Materials and Techniques (Viking, 1982); Joseph Meder, The Mastery of Drawing, trans. Winslow Ames, rev. ed., 2 vols. (Abaris, 1978); Knut Nicolaus, The Restoration of Paintings (Könemann, 1999); Iris Schaefer, Caroline von Saint-George, and Katja Lewerentz, Painting Light: The Hidden Techniques of the Impressionists (Skira, 2008); Kimberly Schenck, “Crayon, Paper, and Paint: An Examination of Nineteenth-Century Drawing Materials,” in Jay McKean Fisher et al., The Essence of Line: French Drawings from Ingres to Degas, exh. cat. (Museum of Fine Art; Walters Art Museum, 2005), pp. 49–57; Silvie Turner, The Book of Fine Paper (Thames & Hudson, 1998); and James Watrous, The Craft of Old-Master Drawings (University of Wisconsin Press, 1957). Framing terms are taken from the glossary to Richard R. Brettell and Steven Starling, The Art of the Edge: European Frames, 1300–1900, exh. cat. (Art Institute of Chicago, 1986).

  • à grain

    • By the late nineteenth century, commercially primed canvas—whether purchased ready-stretched or by the roll—was available in two principal thicknesses of ground application: à grain, indicating a single layer of ground; and lisse, indicating two layers. À grain preparations retain more of the canvas texture than lisse applications.

  • abrasion

    • The removal of media from the surface of the artwork. When mentioned in condition summaries and previous conservation treatments, the term often refers to damage incurred through previous cleaning (with solvents or water) or physical contact with the paint surface. Abrasion by wiping or scraping back paint with a palette knife can also be part of the artist’s technique.

  • absorbent ground

    • A type of ground particularly popular in the second half of the nineteenth century that, often due to its composition, absorbed some of the medium from oil paints, resulting in a faster-drying, matte surface. Although the composition of absorbent grounds varied greatly, many used large proportions of chalk and an aqueous binder such as glue as part of the mixture. See also ground.

  • additive

    • Materials added to paint other than pigments and binders. These can include extenders and materials such as wax or resins, which may function to stabilize the paint or improve its working properties.

  • aqueous lining

    • A lining process that uses an aqueous, or waterborne, adhesive such as glue, paste, or a glue-paste mixture. See also lining.

  • backscattered electron (BSE)

    • See SEM/EDX (scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy).

  • binder

    • The material used to hold various solid, particulate components, including pigments and extenders, of paint together and to the ground or support layer. Traditional paint binders include linseed oil (oil paint), gum arabic (watercolor), or egg yolk (egg tempera). See also oil.

  • binding medium

    • See [glossary:binder].

  • blocked

  • blocking in

  • canvas

    • Textile—usually composed of flax, cotton, hemp, or jute, or combinations of these—used as a primary support for painting and traditionally as a primary or secondary support for pastel or chalk drawings on paper.

  • canvas stamp

  • chamfer

    • A transitional edge between two faces of an object, often created to ease the sharp edge of two adjoining right-angled faces. Also sometimes called a bevel.

  • color merchant

    • Shop selling artists’ materials, including pigments, easels, palettes, oil paints, watercolors, drawing instruments, and supports. These became increasingly common in nineteenth-century Paris and sometimes provided additional services such as framing and restoration. In some cases, supports prepared by a color merchant bear a corresponding stamp on the support verso or stretcher. Also called colormen or marchands de couleur.

  • commercially primed

    • Canvas supports prepared with sizing and ground layers in a large factory or a workshop of a color merchant instead of being primed in the artist’s studio. The result is a roll of pre-primed canvas that can be cut down, either by the artist or a color merchant, and individually stretched for painting.

  • complementary color

    • Color opposite another on the color wheel: red and green, blue and orange, yellow and purple. When complementary colors are in close contact, the color of each is intensified. In the nineteenth century M. E. Chevreul’s treatise, The Law of Simultaneous Contrast of Colors (Le loi du contraste simultané des couleurs), published in 1839, was widely read by artists.

  • consolidant

    • Material, usually solvent- or waterborne, used in conservation treatments to readhere lifting, broken, or flaking materials to the support.

  • consolidate

  • cradle

    • The interwoven wooden strips applied in a grid pattern to the back of the wood panel for reinforcement.

  • cross section

  • cross-sectional analysis

    • For this type of analysis, a microscopic sample—including any combination of support, preparatory layers, paint, and surface layers—is taken, usually from the edge of an artwork or an area of loss, and mounted in a transparent resin. The resin block, once hardened, is ground and polished, exposing all the constituent layers of the sample in one plane. Cross sections can be observed and documented with a microscope in reflected light and ultraviolet fluorescence; they can also be subjected to analysis with SEM/EDX, FTIR, and Raman microspectroscopy.

  • crossbar

    • An additional vertical or horizontal bar that functions to support the main stretcher or strainer members. Also called cross brace.

  • crosshatching

    • A technique in both painting and drawing in which volume or texture is created by two sets of strokes of varying interval and thickness, usually close to perpendicular to one another, that create a kind of X shape.

  • cusping

    • The pattern created along the edges of a stretched textile where the weave distorts in reaction to stretching and the attachment to a secondary support, such as a stretcher. Also called scalloping.

  • darkfield illumination

    • An optical microscopy technique used for the examination of opaque samples, such as paint cross sections. The sample is illuminated from above through the objective and the light is reflected off of the sample so that it appears bright against a dark background.

  • delamination

    • The separation of components of an artwork such as the original support from the lining.

  • differential interference contrast (DIC) microscopy

    • A technique of illuminating and imaging microscopic samples that shows phase differences in the sample in a relief-like fashion. When examining cross sections with reflected light microscopy, DIC enhances certain aspects of the sample and also masks certain types of imperfections, such as scratches due to the grinding and polishing process.

  • drying cracks

    • A condition of painted surfaces caused by uneven rates of drying between layers. Drying cracks can occur in the paint or varnish layers and tend to be wide with rounded edges. Also called traction cracks and shrinkage cracks.

  • edge lining

    • The reinforcing of the tacking margins of a canvas painting by local lining along the edges of the support with a secondary fabric. Also called strip lining.

  • en plein air

  • extender

    • Inert additives, such as calcium carbonate (chalk), calcium sulfate (gypsum), and barium sulfate (barite) to paint and ink, intended to give bulk and dimensionality to the material. Kaolin (hydrated aluminum silicate or China clay) is often used as an extender in chalks, crayons, and pencils.

  • facture

    • The quality of execution of an artwork, typically referring to an artist’s characteristic method of paint handling, including the brushwork or other manner of paint application.

  • figure

  • filler

  • fluorescence

    • Emission of visible light by an object or material when exposed to ultraviolet radiation.

  • foldover

    • The crease made in a canvas where it is folded over stretcher or strainer bars. The original foldover corresponds to the first stretching of the canvas. If a canvas is mounted onto a new stretcher of slightly different dimensions, a new foldover is created. Also called turnover.

  • Fourier transform infrared microspectroscopy (FTIR)

    • A technique that allows characterization of a vast array of materials, such as pigments, fillers, binders, and varnishes. A few microscopic particles of a sample are typically compressed into a thin film, placed under a microscope, and produce a graph—called a spectrum—that shows peaks at the discrete frequencies at which the sample absorbs the incoming infrared radiation. By interpreting and comparing this spectrum with a reference database it is possible to identify an unknown material. Using portable instruments, the technique can also be used noninvasively by collecting the infrared radiation that is reflected off the surface of the work of art examined, without the need to remove a sample.

  • gas chromatography mass spectrometry (GCMS)

    • A technique that allows the precise identification of organic materials such as those used in adhesives, varnishes, and paint-binding media. A microscopic sample is first treated by pyrolysis (controlled heating in an inert atmosphere) and/or chemical preparation to release volatile organic molecules. These are separated by the gas chromatograph (GC) and enter the mass spectrometer (MS), where they are fragmented in an electron beam. Mass spectra, representing “fingerprints,” or patterns of fragments formed from the sample molecules, are interpreted and compared with reference databases to identify the components of the sample. When used with a pyrolysis interface the technique is termed Py-GCMS; pyrolysis can also be performed in combination with a chemical reagent such as tetramethylammonium hydroxide in a technique known as thermally assisted hydrolysis and methylation, or THM-Py-GCMS.

  • graphite

    • An allotropic form of pure carbon used by artists unprocessed as a stick or lump set into a port crayon (metal holder) or compressed into thin rods and encased in wood-cased pencils. In 1795 a substitute for natural and pure carbon, the fabricated graphite pencil, was invented in France. It consists of finely powdered graphite mixed with clay and water and fired at a high temperature. The ratio of clay to graphite determines the hardness or softness of fabricated graphite pencils. Soft pencils require very little pressure to lay down significant amounts of graphite on the surface, creating broad, dark lines, while hard pencils deposit less graphite on the surface and create fine, silvery lines.

  • ground

    • An opaque layer applied to the support, usually over a sizing layer, to prepare the canvas to receive paint. Thinner grounds, including á grain, leave more of the canvas texture apparent, while thicker grounds, including the double-layer lisse, mute the canvas texture. Grounds in the nineteenth century were commercially available in white and a variety of pale colors, and in both absorbent and nonabsorbent consistencies. Also called priming or preparatory layer(s).

  • haute

  • ICA spring stretcher

    • The Intermuseum Conservation Association (ICA) spring stretcher, designed by Richard Buck in 1950, is the most common type of spring-tension stretcher. It is constructed with spring-loaded corners intended to exert continuous, even tension on the canvas as it changes in response to fluctuations in humidity. The stretcher was available, under the name Superior Spring-Stretcher, until 2001.

  • imitation or simulated deckle edge

    • An irregular edge found on opposite ends of a moldmade sheet of paper. They are formed by bands of rubber placed at regular intervals along the wire screen belt of a cylinder mold machine. Moldmade papers are hand torn along the imitation deckle edge during finishing. False deckle edges are narrower and more uniform than true deckle edges.

  • impasto

    • Thick, textural application of paint.

  • impressed watermark

    • A type of watermark found in machine-made paper where a design fabricated in relief, often in rubber, is affixed to a rolling cylinder (called a dandy roll) and rolled over the moving web of damp pulp, pressing the design into it. The impressed design is then visible in transmitted light similar to a watermark.

  • infrared reflectogram

  • infrared reflectography

    • This technique exploits the varied transmission, absorption, and reflection properties of infrared radiation by artists’ materials. The degree of penetration depends on the thickness of the paint, the pigments used, and the wavelength of the infrared radiation. Many paints appear partially or completely transparent, while others, such as black, absorb the infrared radiation and appear dark. An infrared-sensitive camera captures the light reflecting from the artwork. The resulting image is known as an infrared reflectogram. Infrared reflectography is used to distinguish pigments, inscriptions, underdrawings (particularly those done in carbon-rich materials such as charcoal and pencil over a white or light-colored ground), and changes in a composition not visible to the naked eye.

  • inpainted

  • inpainting

    • Painting done by a conservator to restore areas of loss or damage in an original paint layer. Inpainting is limited to the area of loss and is carried out in a medium that remains readily distinguishable from the original, does not discolor, and can be easily removed in the future. Also called retouching.

  • IRR

  • keying out

    • The act of tapping the keys to expand the stretcher and increase tension on a canvas support. See also keys.

  • keys

    • Small wedges, often roughly triangular in shape, inserted into the joints of a stretcher to allow the stretcher to be expanded and tension on the canvas increased. This process is called keying out or tapping out.

  • laid in

  • lake pigment

    • A translucent pigment made by precipitating a dye onto an inert substrate. Lake pigments can be made from naturally-sourced or synthetic dyes; common examples include alizarin, madder and carmine (cochineal).

  • lay-in

  • laying in

    • The act of establishing either the major elements of a work in solid paint or the initial paint layers. The lay-in is a form of underpainting, also referred to as the ébauche or block-in.

  • lined

  • lining

    • The act of structurally reinforcing the original canvas or paper support with a similar or like material to provide strength or reinforcement to the artwork. A painting can be lined with a second textile or canvas with an adhesive, typically aqueous materials, wax-resin mixtures, or BEVA 371 (a trademarked thermoplastic adhesive developed for the conservation field by Gustave Berger in 1971, containing varying amounts of ethylene vinyl acetate copolymer, ketone resin, and wax). Works of art on paper are traditionally lined with Japanese kozo (paper made of the inner bark fibers of the mulberry plant), adhered overall with prepared wheat starch paste.

  • lisse

    • By the late nineteenth century, commercially primed canvas—whether purchased ready-stretched or by the roll—was available in two principal thicknesses of ground application: à grain, indicating a single layer of ground; and lisse, indicating two layers. A lisse (French for “smooth”) application fills the interstices of the canvas weave to a greater degree than à grain applications.

  • marine

  • metal soap formation

    • A condition in which new compounds form when metallic components in pigments or driers in the paint or ground layers react with fatty acids in the oil binder or varnish. Frequently these metal soaps form aggregates that can move toward the surface of a work, appearing as small, sometimes white protrusions or bumps. These protrusions can sometimes cause cracks, losses, and destabilization of the paint layer(s) over time.

  • millboard

    • A sturdy, thick paperboard used in bookbinding and box making. Often used for structural stability as a secondary support upon which paper was adhered or wrapped for drawing; it could also be used as a drawing or painting surface in its own right.

  • miter

    • A way of joining two abutting members such that both are carved at equal angles to create the desired angle of the joint. For example, in most frames and stretchers, both members would be cut at a forty-five-degree angle to make a ninety-degree joint.

  • modeling

    • In two-dimensional art forms (such as drawing or painting), modeling is the depiction of three-dimensional objects achieved through the representation of light and shadow.

  • natural-resin varnish

    • A varnish made from a dissolved resin of natural (plant or insect) origin. Natural resins include damar and mastic.

  • oil

    • In the present study, this term generally refers to drying oils used in artists’ paint, usually linseed oil but also poppy and walnut oils, among others. Drying oils form a hard film when exposed to air and cure over time.

  • overpaint

    • Paint or restoration material applied over the artist’s original paint. Most often applied by another artist or a restorer at a later date, overpaint was used to cover damages and make aesthetic changes to the artwork. It is often excessive and is generally avoided in favor of localized inpainting.

  • painting knife

    • A tool used for paint application. Distinct from a palette knife, which also can be used to apply paint, painting knives come in a range of shapes and sizes, and typically have an angular shape and an offset handle to keep the painter’s hand away from the surface of the painting.

  • palette

    • Either the range of colors used by an artist for a particular work, or the hard surface used by an artist to stage and mix colors.

  • palette knife

    • A spatula-like tool used for mixing and applying paint and ground layers. Palette knives usually consist of a handle and a thin, flexible, blunt-tipped metal blade.

  • panel

    • Traditional description for flat, wooden supports used for painting. The term can also refer to more modern supports such as hardboard and Masonite.

  • paysage

  • pentimento (pl. pentimenti)

    • A visible trace of a compositional change made by the artist during an artwork’s execution.

  • pentimenti

  • photomicrograph

    • An image taken through a microscope.

  • picture plane

    • The imaginary plane in the image that corresponds to the surface of the picture.

  • pigment

    • Colored particles used in artistic media such as oil paint, pastel, chalks, and watercolor.

  • plain weave

    • Weave structure where the weft threads are woven over and under every other warp thread reversing the over-under sequence with each subsequent pass of the weft. Also called tabby weave.

  • plein air

    • The act of painting or drawing outdoors.

  • pochade box

    • A portable box designed for painting en plein air, with compartments to hold supplies, such as painting support, paints, brushes, and palette. The lid provides a working surface.

  • pre-primed

    • Indicates a canvas that was primed before being cut to size and mounted on a stretcher. The presence of ground extending to the edges of the canvas is indicative of pre-priming. Canvases were sometimes pre-primed by an artist or assistant, but, by the second half of the nineteenth century, more commonly by commercial manufacturers or color merchants who sold pre-primed canvas ready-stretched or in rolls or by the meter for artists to stretch themselves.

  • preparatory layer

  • primed

  • priming

  • radio opaque

    • A term used to describe materials of high atomic weight (for example, lead white paint), which block X-rays and appear light in X-ray images. See also X-radiography.

  • radio transparent

    • A term used to describe materials of low atomic weight (for example, canvas), which are easily penetrated by X-rays and appear darker in X-ray images. See also X-radiography.

  • raking light

    • Illumination from an oblique angle used to highlight the topographical features of an artwork.

  • Raman microspectroscopy

    • This technique can be used to identify a wide range of materials nondestructively. Using a microscope, spectra can be recorded from samples as small as 1 micron (1 μm = 1/1000 mm) across, and individual pigment particles can be analyzed, either as loose samples or on the surface of cross sections. Visible or invisible laser light is focused through a microscope, and the small portion of light that interacts with the material under study (a phenomenon known as the Raman effect) is scattered back into the microscope onto the detector. This scattered radiation is recorded as a function of wavelength and displayed as a spectrum, a graph in which each particular compound has a characteristic fingerprint. Complementary to FTIR, this technique can characterize inorganic materials such as metal alloys and mineral and synthetic pigments and fillers and some organic compounds, although with organic substances it is sometimes impaired by the fluorescence of the materials under the laser.

  • rebate

    • Small margin inside a frame against which a work of art rests. Also called rabbet.

  • repaint

  • retouching

    • This term is commonly used interchangeably with inpainting; however, it can also refer to overpaint or repaint, generally in reference to a conservator’s intervention. Retouching may also include toning of original paint that has been damaged or abraded.

  • scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX)

    • This technique utilizes electrons, rather than light, to create an image of a sample. It allows for the analysis of very small quantities of materials. The sample is coated with a thin film of carbon or gold, and a small beam of electrons is focused on the sample’s surface. Secondary electrons allow scientists to obtain a three-dimensional image at very high magnification and resolution (up to 100,000×); backscattered electrons (BSE) highlight the distribution of the elements, recording them in different shades of gray according to their atomic weight; and X-ray fluorescence emission allows analysts to determine which elements are present and to infer inorganic (mineral and synthetic) pigments and fillers. The EDX spectrum consists of a graph containing a series of peaks, each one occurring at a precise energy characteristic of a particular element. It is important to note that this technique gives information about what elements are present in a sample but not about their relationships to one another; it also does not indicate the organic compounds (such as binding medium) present. For these reasons, it is best complemented with polarized light microscopy or a molecular fingerprinting technique such as Raman microspectroscopy or FTIR.

  • scanning macro X-ray fluorescence spectroscopy (macro-XRF)

    • This technique creates an image of the distribution of specific atomic elements contained in the paint layers of an artwork. An XRF spectrometer is scanned across the area of interest (which may be the entire artwork or only portions of it) and collects XRF spectra for individual spots in successive rows, which are then combined in a single image mapping the distribution of each element in the area examined. These images can be used to formulate hypotheses on the distributions of specific pigments and extenders at or below the surface of the artworks scanned.

  • selvage

    • A strip of the woven fabric running along the outer warp threads where the weft changes direction without being cut, thus preventing fraying. There is a selvage at each end of the fabric width. The selvage is often woven differently than the body of the fabric and sometimes includes a colored thread identifying the manufacturer.

  • sinking in

    • As a paint dries or ages, it may lose its gloss and deep, rich tone unevenly due to absorption of the paint medium by underlying layers.

  • size

    • See [glossary:sizing].

  • standard-size supports

  • standard format

    • The range of ready-made commercial supports—canvas, panel, paper, and card—available in an array of fixed sizes that are constant regardless of manufacturer. Standard-size supports are numbered from 1 to 120 and are available in three shapes: portrait (figure), landscape (paysage), and seascape (marine). These three formats have their longer dimension in common, with the short side becoming progressively shorter, so that the portrait format is the closest to being a square, the seascape the narrowest, and the landscape between the two. Some suppliers offered additional variations on select landscape and marine formats, further classifying them as haute (tall) and basse (short). The dimensions of these supports range from 12 to 130 by 22 to 195 cm.

  • stretcher

    • The wooden framework with expandable joints over which a canvas painting is stretched and attached. It is the secondary or auxiliary support for a canvas painting. Also called a chassis.

  • stumping

    • A drawing technique used to blend powdery media in which a piece of soft paper, felt, or leather, rolled to form a point (stump), is held at an angle and rubbed back across the paper surface to transfer the media.

  • support

    • The physical surface upon which an artwork is executed. Can include textiles, wood, and other types of board, metal, and paper.

  • surface-enhanced Raman spectroscopy (SERS)

    • A type of Raman microspectroscopy that requires specific preparation of the sample before analysis. Because of its extremely high sensitivity and its ability to quench fluorescence, it is particularly well suited to the identification of natural organic colorants like those used to make lake pigments. A silver colloid, a suspension of silver nanoparticles obtained by chemical reduction of a silver salt (generally silver nitrate), is typically employed. Prior to analysis, the sample is exposed to hydrofluoric acid vapors in order to increase the absorption of the dye on the metal surface of the silver colloid, thus enhancing the SERS signal. After that, a small drop of the silver colloid is deposited onto the sample and analysis is carried out with a Raman microscope.

  • synthetic varnish

    • A type of varnish introduced in the twentieth century that is comprised of a dissolved synthetic polymer.

  • tacking edge

  • tacking margin

    • The edges of the textile support that extend over the sides of the stretcher or strainer and by which the support is attached, often with tacks. Also called tacking edge.

  • thread count

    • The number of warp and weft elements in a textile per linear unit of measurement. This can be estimated by localized, manual counting or determined by specially developed automated software. Researchers from the Thread Count Automation Project—including Rick Johnson of Cornell University; Don Johnson of Rice University; and Robert G. Erdmann, Rijksmuseum, Amsterdam, University of Amsterdam, and Radboud University, Nijmegen—use a program that precisely counts the threads in a canvas and maps variations in the weave density from an X-ray. The results can provide information about weaving and priming processes and can be used to identify canvases cut from the same fabric.

  • tonal

  • tonality

    • The way areas of relative lightness and darkness interrelate in an artwork

  • tone

    • Either the relative lightness or darkness of a color (value), or the act of glazing or scumbling for the purpose of changing the color slightly. Toning can sometimes refer to a conservator or restorer’s retouching over abraded original paint.

  • toned

  • toning layer

    • A thin layer of color, applied locally or over the entire ground layer, that modifies the tone of the final paint surface.

  • tooth

    • The roughened quality of a surface, such as a painting support, which enhances the adhesion of paint or other coating layers.

  • transfer paper

    • A thin paper coated on one side with a water-soluble substance such as gum that transfers a design made in greasy media like litho crayon or tusche onto another surface through the application of moisture and pressure. Used for lithography (and zincography), some types of transfer paper imparted a regular laid line texture onto the matrix, others came in a variety of grains from coarse to fine; some had no grain at all.

  • transmitted-infrared imaging

    • This technique is similar to infrared reflectography (IRR), except that the light source is placed behind the canvas, painting, or drawing so that the light is transmitted through it. It has proved especially useful in discovering artists’ changes that are not visible in X-ray or reflected-infrared images, as well as original canvas stamps obscured from view as a result of lining.

  • transmitted-light imaging

    • Imaging a work of art, usually with a canvas or paper support, illuminated from behind so that the light passes through the artwork.

  • ultraviolet (UV)

    • Invisible to the naked eye, UV radiation has energies beyond the visible light portion of the electromagnetic spectrum. Materials at the surface of an artwork may exhibit fluorescence in characteristic colors in response to UV radiation, depending on their chemical composition. For example, zinc oxide typically has a greenish-yellow fluorescence when viewed under UV, while certain red lakes often display a pinkish-orange fluorescence. UV-induced fluorescence is visible to the naked eye and can be documented photographically. UV imaging is used to help verify or differentiate surface coatings, pigment composition, and reworkings or restorations and can aid in their identification when coupled with other means of point analysis. UV radiation is also routinely used to study the fluorescence from constituent layers of cross sections under a microscope.

  • underdrawing

    • Compositional sketch drawn usually directly on top of the ground layer in painting or directly onto the paper support in watercolor. Underdrawings can vary in media and level of detail, from simple contours to drawings that are volumetric and heavily detailed.

  • underpainting

    • The initial painted layers of a work, which are often subsequently covered. Underpainting can include the initial laying in or blocking in of major compositional forms. Also called ébauche.

  • unvarnished

    • Without varnish.

  • varnish

    • Resin-based surface coatings on a work of art. Spirit varnishes are made with resins dissolved in a volatile solvent that harden to form a film as the solvents evaporate. These coatings are usually transparent and are intended to protect the surface of a painting from grime and pollution, saturate the colors, and produce a consistent surface gloss.

  • varnishing

  • warp thread

    • Fixed longitudinal threads on the loom during the weaving process.

  • wash

    • Thin paint layer produced by diluting the paint with water or solvent, depending on the binding media. Washes tend to appear more matte and are more liquid than glazes or semiglazes.

  • watermark

    • Formed in paper by attaching wire designs (such as coats of arms, crests, or letters) to the paper mold screen; fewer fibers collect over the wire designs during the sheet formation, resulting in thinner areas visible in transmitted illumination. Watermarks can be studied to learn more about the paper’s date and manufacture.

  • wax-resin lining

    • Process of lining a painting using a mixture of wax and natural resin as the adhesive. See also lining.

  • weave

    • Woven pattern in textiles created by overlapping warp and weft threads. Common weave patterns include plain, or tabby, weave; twill; and basket weave.

  • weft thread

    • In the weaving process, the weft threads are laterally woven through the fixed warp threads.

  • wet-in-wet

    • The application of wet paint onto a still-wet paint layer; the two paints may be blended or mixed together on the canvas. The presence of wet-in-wet paint application can be used to identify parts of a picture that were painted within a short time frame. Also called wet-into-wet.

  • wet-on-wet

    • The application of wet paint onto a still-wet paint layer without mixing or blending the two paints.

  • wet-over-dry

    • The application of wet paint onto a paint layer that has already dried or set up. This generally indicates some passage of time between the two applications. Also called wet-on-dry.

  • wove paper

    • A type of handmade or machine-made paper formed on a mold screen of finely woven wires lacking the pattern of laid and chain lines. When the paper mold is dipped into water containing a fine dispersion of paper fibers, the fibers settle onto the wire screen as the water drains off; the formed sheet bears the wove wire screen pattern that is most clearly seen when light is transmitted through the paper sheet.

  • X-radiography

    • X-radiography involves exposing a painting to X-ray radiation and imaging the transmitted X-rays on film or digitally. Materials vary in their ability to absorb or transmit the radiation, depending on their thickness, density, and chemical composition. X-radiography can reveal changes in composition, artist’s brushwork, damages, and details in the support not visible to the naked eye. Because all of the layers of the painting are superimposed on one plane, the reading of X-ray images (commonly called X-rays) requires careful interpretation.

  • X-ray

  • X-ray fluorescence spectroscopy (XRF)

    • This noninvasive means of analysis utilizes a focused beam of X-rays to excite the atoms that constitute the artwork and measure the emitted energy. It provides a characteristic fingerprint of the elements contained in the sampled volume, thus allowing to formulate hypotheses on the artwork's inorganic components (pigments, extenders, metallic elements, and the like, but not binding media or organic pigments). In the case of paintings and works on paper, the sampled volume often includes all painting layers and may also include information about the support.

  • BIBLIOGRAPHIC REFERENCES

  • Catalogues

  • C

    • Stratis, Harriet K. and Martha Tedeschi. The Lithographs of James McNeill Whistler. 2 vols. Chicago: Art Institute of Chicago, 1998.

  • K

    • Kennedy, Edward G. The Etched Work of Whistler. Rev. ed. San Francisco: Alan Wofsy Fine Arts, 1978.

  • M

    • MacDonald, Margaret F. James McNeill Whistler: Drawings, Pastels, and Watercolours; A Catalogue Raisonné. New Haven, CT: Yale University Press, 1995.

  • YMSM

    • Young, Andrew McLaren, Margaret F. MacDonald, Robin Spencer, and Hamish Miles. The Paintings of James McNeill Whistler. 2 vols. New Haven, CT: Yale University Press, 1980.

  • L

    • Lochnan, Katharine A. The Etchings of James McNeill Whistler. New Haven, CT: Yale University Press, 1984.

  • Institutions

  • HAG

    • Hunterian Art Gallery, University of Glasgow

  • LC

    • Library of Congress, Washington, DC

  • Literature

  • GUW

  • Andrew Young et al.

    • Young, Andrew McLaren, Margaret F. MacDonald, Robin Spencer, and Hamish Miles. The Paintings of James McNeill Whistler. 2 vols. New Haven, CT: Yale University Press, 1980.

  • Levy

    • Levy, Mervyn. Whistler Lithographs: An Illustrated Catalogue Raisonné. London: Jupiter Books, 1975.

  • MacDonald (1995)

    • MacDonald, Margaret F. James McNeill Whistler: Drawings, Pastels, and Watercolours; A Catalogue Raisonné. New Haven, CT: Yale University Press, 1995.

  • MacDonald and Petri

    • MacDonald, Margaret F. and Grischka Petri. James McNeill Whistler: The Paintings; A Catalogue Raisonné. Glasgow, UK: University of Glasgow, 2014. Online edition at http://whistlerpaintings.gla.ac.uk.

  • Way

    • Way, T. R. Mr. Whistler’s Lithographs: The Catalogue. London: George Bell and Sons, 1896.

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