Florence at the Height of the Renaissance, by Giorgio Vasari (1511-1571)

 This essay is the second of a two-part series, and deals with the materials, techniques and physical history of easel picture-painting in Italy during the fifteenth and sixteenth centuries. It is inspired by looking closely at the collections of the National Gallery in London, England.    

 While there were certainly differences in the practice of painting north and south of the Alps – some mentioned in Part I and some to be discussed here – the similarities have often been underestimated. While a new Renaissance culture emerged first in Italy, and only slowly in spread to northern Europe toward the end of the fifteenth century, it would be misleading to conclude that Italy was always the primary source of cultural and artistic innovation. To do so doesn’t take into account the diversity of regional practices in both northern and southern Europe. Italy, for example, was not a unified entity but rather, an ever-shifting assemblage of independent political entities with varied histories, economies and cultural affiliations. We also tend to underestimate the speed with which ideas spread throughout Europe, even without the help of modern technology. Keeping this in mind, much of what was discussed in Part I regarding northern European painting, especially in Flanders, holds true for Italy: easel painting moved from panel to canvas, from tempera to oil, and from multi-part to single field formats, while the range of subject matter widened. Fine Arts Magazine   

Raffaello Sanzio da Urbino, Self Portrait, tempera on wood (1506). Gallery Palatina, Florence

  The medieval practice of painting on panel gave way to using canvas more rapidly in Italy, but this only occurred in one particular place. In fact, major centers such as Florence were as slow to give up panel painting as comparable cities in Flanders. The example of Raphael, one of the most famous of all Italian Renaissance painters despite his early death in 1520, is a case in point. During a prolific career that took him from Umbria to Florence and Rome, he painted less than a handful of known pictures on canvas in any genre. Painters working for the élite, as Raphael was, had little motivation to flout conventions that valued paintings on panel as more expensive to produce, more permanent, and hence more desirable than the more ephemeral paintings on fabric (which had their own long-standing tradition). It was the painters of the Republic of Venice who were the innovators in producing easel pictures on canvas. Why this was so is still a matter for discussion. The production of canvas was well-established in Venice during the Middle Ages, thanks to the demands of an extensive maritime commerce, and hence of a ship-building industry centered at the state-subsidized Arsenale, the largest shipyard in the world by the thirteenth century. Furthermore, the watery, damp environment of the city discouraged demand for fresco painting, which had become the preferred technique for decorating masonry walls throughout Italy. Frescos were the exception in Venice, although patrons did occasionally demand them, especially for exterior walls, ironically the most fragile of all; they have long-since vanished from the city’s buildings (although there are traces still to be seen in mainland cities that were formerly part of the Republic such as Treviso and Bassano del Grappa).    

Medieval painter's pattern book, c. 1450. Coll. British Library

  Painters and patrons rapidly took to the new practice of creating painted canvasses for interior walls. In the second half of the fifteenth century, narrative cycles were painted on canvasses stretched on wooden frames (now called “stretchers”), that in any other Italian city would have been applied as fresco to plaster walls. By the early sixteenth century, canvas was the norm for other genres, as well: portraits, pictures with newly-fashionable classical subjects, devotional pictures, and even altarpieces. As ceiling paintings on canvas began to rival wall paintings in popularity, and as bothtypes of pictures grew larger in size, standard widths of material had to be stitched together to achieve the desired size; the resulting seams can sometimes be detected by looking closely. Canvas could also be reused. The Venetian painter Tintoretto, who covered acres of wall and ceiling with his huge pictures, was particularly known for piecing together his canvas, sometimes of different weaves and sometimes re-cycled.    

Leonardo da Vinci, Composition Studies for the Last Supper (1490s), red chalk on paper. Venice, Gallerie dell’Accademia

 In fifteenth-century Italy, as in northern Europe, underdrawings were ubiquitous and generally quite detailed. That they were based on preparatory sketches executed in various media on paper – the latter in general use since the later Middle Ages – is generally assumed, although few single sheet drawings survive from before 1420 or so anywhere in Europe. The medieval painter’s workshop practice of maintaining “pattern books”, full of detailed studies that included figural poses, drapery, ornamental motifs, and plants and animals, encouraged the reuse of previously-executed drawings in the composition of paintings. Pattern books were valued possessions, often passed down from father to son. They seemed to have fallen out of favor in the fifteenth century as the preparatory process was expanded to include many more studies for a given work, usually on single sheets, and ranging from studies of individual hands or heads, for example, to general compositional arrangements.    

Leonardo da Vinci. Virgin and Child with Saints Anne and John the Baptist (c. 1506-08), charcoal, chalk and wash on paper, National gallery, London (NGL)

 The most celebrated practitioner of this expanded creative process was Leonardo da Vinci, whose career began in Florence in the 1470s. His drawings demonstrate that the process of composing a painting was, in theory, endless. His studies ranged from the macrocosm to the microcosm, breaking forms down into their component parts, and those, even smaller, switching figure poses from left to right and then from right to left, turning a sheet over to continue a visual idea on the reverse when the first side became undecipherable. It was conventional practice by this time for a painter to create a “presentation drawing” to show a patron what his picture would look like s, and then frequently, a “cartoon”, which was the painter’s guide for the painting process itself. These two types of drawings usually strove for clarity rather than elaboration. One of Leonardo’s drawings – probably intended as a presentation drawing or a cartoon – was so highly finished that it created a sensation and was put on public exhibition in Florence in 1501. That drawing is lost, but the one shown here, The Virgin and Child with St. Anne and St. John the Baptist, is considered similar, and a variant of the same subject, although a few years later in date. It is not only a testament to Leonardo’s skill, but also a crucial piece of evidence for the profound change in the role and status of drawings taking place around 1500. They were no longer just workshop props, but potential works of art in their own right, documenting the new value placed on the creativity and fame of individual painters, and worthy of being collected by connoisseurs.    

Giovanni Bellini, Madonna of the Pear (Virgin and Child) (c. 1488), oil on panel. Bergamo, Accademia Carrara

 Most drawings were still used to create paintings, however. Even highly successful painters reused ideas and motifs already captured in drawings by tracing or pouncing. Copy and reuse had been guiding principles of workshop practice since the Middle Ages. Apprentices learned by copying, more often from the master’s pattern books than from nature. Their aim was to emulate the master’s style, a skill that enabled an apprentice to rise to the level of assistant and begin to work on the master’s pictures. Even as some painters began to expand the creative process in the fifteenth century, and as most encouraged their pupils to copy from nature as well as from their drawings, workshops routinely made replicas and variants of completed pictures and continued to do so throughout the Renaissance. Some of these were produced at the request of patrons (especially if the original was owned by someone of higher status), while others were sold on the open market. The latter were produced without an advance commission, although a picture could always be “personalized” at a patron’s request with a different background, more use of expensive pigments (especially gold), or the addition of a coat of arms or even a portrait.    

Workshop of Giovanni Bellini, Virgin and Child (c. 1475), oil on panel, NGL

 Giovanni Bellini, the most famous painter in Venice during the late fifteenth century, inspired and taught a generation of “madonnieri” who often specialized in devotional images of the Madonna and Child in the manner that he had popularized; most especially the half-length Madonna holding the Christ Child in front of a landscape, often behind a parapet, as seen in the two examples shown here – one by Bellini, the other attributed to his workshop. The number of surviving Venetian pictures of this subject testifies to the demand that must have existed, and suggests that a few of Bellini’s assistants specialized in the genre after setting up their own shops. Most buyers would have been satisfied with such a replica or variant “in the manner of Bellini”, even if it did not come from his hand or even from his shop, and the price would have been more affordable. Modern notions of the value of originality did not apply in the Renaissance, nor did that of copyright, although this is certainly the first period in western art when the idea of originality began to affect the reputation of artists and the price of their paintings and drawings.    

Cima da Conegliano, The Incredulity of St. Thomas (c. 1502-04), oil on panel, NGL

 As seen in Part I, Netherlandish painters took the lead in using oil paint for easel pictures early in the fifteenth century. Until recently, art historians assumed that this technique was first brought to Venice in the 1470s and was adopted enthusiastically by Venetian painters before it appeared elsewhere in Italy. Scientific analysis now suggests that the Italians were experimenting with oil as early as the 1450s, likely inspired by the Flemish pictures acquired by wealthy merchants and aristocrats, and by actual contact with the Flemish working in a number of cosmopolitan centers, including Ferrara and Venice. What was exceptional about the Venetian painters was their rapid, widespread adoption of the oil medium, as we see in the pictures of Giovanni Bellini (c. 1450-1516) and his contemporary Cima da Conegliano (c. 1459-c. 1517). The practice of glazing with pigments mixed in oil was the foundation of the Flemish approach (as discussed in Part I). Venetians pursued the same values as their northern models: reflectivity of light, glowing color, detailed description of material objects, and smoothly-finished surfaces where no brush stroke or other mark could be detected. Yet they also seem to have contributed to the evolution of the technique, especially in searching for more subtle, varied coloristic effects. Cima’s much-studied altarpiece, The Incredulity of St. Thomas, from c. 1502-04, is a case in point. Cima deepened the shadow of the Apostles’ draperies not only by the conventional practice of overlaying glazes of the same or related hues, but also by the much less common practice of glazing with the complementary hue, notably in the green draperies of the figures in the front row, where his final layer of glaze is a red lake. This achieved the desired effect of darkening the shadows and toning down the brilliant green, but simultaneously created a more complex hue, one not muddied by the addition of brown or black.    

A Renaissance apothecary, where pigments could be purchased

 Cima’s painting is often cited as an example of the expanding variety of the Venetian painters’ palette, most vividly seen in the brilliant orange-yellow of St. Peter’s robe. The artist used two related pigments here, both sulphides of arsenic that were seldom used in the fifteenth century, but would become signature pigments of sixteenth-century Venetian painting: the yellow orpiment and the orange realgar. Venice was a destination for the acquisition of pigments by out-of-town painters. Furthermore, by the 1490s, perhaps earlier, those pigments were sold by specialist “color sellers” (“vendecolori”). It was a profession unique to Venice at this time. Throughout the remainder of Europe (including the rest of Italy), pigments were sold by generalist apothecaries, as they had been since the Middle Ages and would continue until later in the sixteenth century. Specialist vendecolori may very well have tried to increase demand by offering new or, unusual products, and we think that their shops became destinations for a variety of artisans who used colorants to share ideas as well as purchase supplies.    

As painters in other central and northern Italian centers began to shift to oil, albeit more slowly than had the Venetians, they also experimented with the technique. Three panels from Perugino’s Certosa di Pavia Altarpiece, c. 1496-1500, provide a useful example. The technique used in the blue drapery of the Archangel Raphael is representative of a painter transitioning between tempera and oil. The underpaint is tempera, but the choice of a light (off white) hue is typical of the light-to-dark process of oil glazing, and the glazes added over the tempera layer are ultramarine mixed with oil, thus creating a rich blue, but allowing light to reflect off the underlying white and back through the translucent, blue-tinted layers of oil. Scientists at the National Gallery have found unusual mineral substances in some of Perugino’s pictures, including this, as well in those of many of his contemporaries, including Raphael. Here the underpaint of St. Michael’s armor is a combination of lead white with lustrous particles of a tin-rich bronze powder, also found in the off- white underlayer of Archangel Raphael’s blue garment discussed above. While the metallic gleam of the pigment would have been compromised or invisible mixed with opaque lead -white for underpaint, it is still intriguing to speculate that Perugino chose to experiment with this substance as he contemplated how to achieve the metallic appearance of St. Michael’s armor.    

Perugino, Certosa da Pavia Altarpiece (dismembered), (c. 1496-1500), tempera and oil on panel, NGL

 Powdered glass is another substance found in the glaze layers of Perugino’s paintings, and also in early works of his younger co-worker Raphael (who was possibly Perugino’s assistant at one time) such as the Mond Crucifixion from c. 1502-03. The glass would seem to be an additive not intended to affect the final appearance of the picture, but that subject is still open to debate. Was the glass simply a drying agent for the oil (painters had to wait for each layer to dry before adding the next), did it act as an extender, adding body to the very soluble red lake paint (where it is most often found), and/or were the particles of glass intended to add more sparkle to the final surface? Not coincidentally, we begin to see some painters at this time showing other evidence of an increasing sensitivity to the appearance of their oil paints by selecting their oil binder dependent on the hue of pigment used, as was the case in Raphael’s Crucifixion. He used the less common walnut oil as a binder for the whites and light blues of the sky because it showed less tendency to yellow, while continuing to employ linseed oil for more saturated hues where yellowing would not be a factor, linseed oil more generally preferred as it dried faster than walnut.    

Raphael, Mond Crucifixion (c. 1502-03), oil on panel, NGL

 Raphael’s picture also provides an early example of other changes in painters’ approaches to the oil technique, this time in its application, rather than in the nature, of the pigments. In the shadows of St. Jerome’s pale, purple-grey robe, Raphael used hatched brush strokes to create the shadows rather than floating successive glazes of red and/or blue to create a darker tone ( the National Gallery scientists point out that this area has altered to appear reddish-brown rather than the purple originally intended by the artist). The highlights in the subdued robe of the Madonna were glazed to allow the lighter under layers to show through, but instead of using a brush, Raphael used his fingers and the marks are visible. When painters began to leave marks with their paint, intentionally or not, they were beginning to manipulate the viscosity of oil paint in a way that interrupted the traditional anonymous, mirror-like finish of the final paint layer.    

Titian, Noli me Tangere (c. 1514), oil on canvas, NGL

 Here again it was the Venetian painters who most aggressively pursued new approaches to the oil technique that exploited the malleability of oil-based pigments as much as their transparency (although glazing was by no means abandoned). Titian (c. 1486-1576) and Giorgione (c. 1478-1510), a generation younger than Giovanni Bellini, but much indebted to him, took the lead. Titian’s Noli Me Tangere of c. 1514 provides a vivid example in the white loincloth of Christ. A relatively lean mixture of pigment and oil – using less oil to make the pigment thicker and stiffer – allowed the painter to accumulate the paint in globs that sat above the painted surface when applied with the brush. This is usually referred to as “impasto”, and it was used above all to create the optical impression of highlights. Furthermore, with a dry brush dipped in this mixture, a painter could drag the brush across the surface in a technique called “scumbling”, to produce the optical effect of transparency without glazing (an effect that would have been amplified by allowing the texture of the canvas to play a role). These approaches might be termed “optical approximation” as opposed to the descriptive application of oil paints that were then glazed to alter values, enrich hues and create life-like light effects.    

Veronese, Dream of St. Helena (c. 1570), oil on canvas, NGL

 Subtle distinctions in the texture of fabrics, even those of a single color, became a hallmark of this painterly style. As black became the fashionable color for the clothing of European élites in the sixteenth century, it was inevitably the color most often used in portraits. Painters rose to the challenge of monochromy by employing a full range of optical “tricks” to convey the differences between velvet, silk, wool and satin. These tricks included applying impasto, varying the direction and length of brushstrokes, and scumbling, in addition to glazing, varying hues by juxtaposing different black pigments (soot blacks, for example, produced a bluer black than bone blacks), and mixing in other colors. These subtleties are difficult to see in reproduction, especially in painterly pictures where heavy varnishes or past damage have abraded the three-dimensional surface. Such pictures are better examined “in person”, and we illustrate this point instead with a brighter, more colorful example by the Venetian painter Veronese (1528-88), his Dream of St. Helena of c. 1570, where one can see the play of the golden impasto highlights on her pink tunic, and for the blacks, a portrait by the Florentine Bronzino (1503-72). His Portrait of a Young Man of c. 1550, which also demonstrates that not all Italian painters adopted the Venetian’s painterly approach. Bronzino and his Florentine patrons preferred the slick, impersonal surfaces of traditional glazed paintings and an approach that relied more on traditional description than optical approximation. A closer look reveals, however, that despite his hard-edged contours, Bronzino’s interior modeling often relied on fluid transitions between colors produced by painting one pigment into another that was not yet dry, a technique referred to as “wet on wet”.    

Bronzino, Portrait of a Young Man (c. 1550), oil on canvas, NGL

 Finally, the framing of these simple rectangles of canvas, already stretched and nailed onto a wooden “stretcher”, was a relatively simple process. The taste for gilded frames seems to have been at least partially overtaken by a preference for frames of unpainted wood, often carved and sometimes touched up with gold. Venetian household inventories from the sixteenth century invariably refer to these frames as “walnut”, although it is impossible to know from the notaries’ generic short-hand how many were actually fashioned from that wood. These frames relate, not surprisingly, to contemporary taste in furniture, in which carved wood prevailed, with or without gilding; that was very different from the taste of earlier periods when furniture was invariably painted. What little we know about the price of frames suggests that they cost less than their earlier counterparts, often more elaborate (in part because they were used primarily for altarpieces and smaller religious pictures). In all periods it was certainly the cost of gold that drove up the price of a frame, although as new genres of picture appeared (in the period under discussion here, for example, portraits and pictures with classical subject matter), and as the formats were so often simple rectangles, carpenters and wood carvers could more easily find ways to simplify production and reduce costs.    

Looking closely at paintings as material objects is aesthetically rewarding. It also opens up the world of the past in at least some of its complexity, allowing us glimpses of the tastes and fashions, technologies, economies, and cultural aspirations of Renaissance painters and consumers. Coincidentally, the National Gallery in London is holding an exhibition from 30 June until 12 September, 2010 entitled Close Examination: Fakes, Mistakes and Discoveries(www.nationalgallery.org.uk ) that explores some of these issues and also illuminates the role of conservation and scientific analysis in helping us to understand what we see.    

The author is indebted to the work of conservators and restorers at many museums in North America and Europe, but most especially to Dr. Barbara Berrie at the National Gallery of Art in Washington, DC and the scientists and restorers at the National Gallery of Art in London, UK. The latter’s important publication, The National Gallery Technical Bulletin has some articles accessible to the non-specialist, and the Gallery’s relatively new “Raphael Research Project” is an exceptional resource, providing a wealth of technical information and useful bibliography to all.    

by Louisa C. Matthew, Ph.D., Contributing Writer    

Louisa Matthew received her Ph.D. from Princeton University in 1988 with a thesis on the altarpieces of the Venetian painter Lorenzo Lotto. In addition to publications on Lotto, has published on painters’ signatures in Venetian Renaissance pictures and contributed to exhibition catalogues on various aspects of the same period. Recent work deals with the history of pigments in Venice, not only their use by painters but also their manufacture and commerce.    

A study of the profession of color seller in Venice, prompted by the discovery of a trove of documents in the Venetian state archives, has led to an on-going collaboration with Dr. Barbara Berrie, a chemist and senior conservation scientist at the National Gallery of Art in Washington.    

Louisa Matthew is currently, professor of art history in the Department of Visual Arts at Union College, in Schenectady, NY. Grants have included a fellowship at Villa I Tatti, the Harvard center for Italian Renaissance Studies in Florence Italy, a paired fellowship (with Dr. Berrie) at the Center for Advanced Study in the Visual Arts at the National Gallery of Art, and grants from the Delmas Foundation.

Christus, Petrus (ca.1410-1475-6). A Goldsmith in His Shop, Possibly St. Eligius (1449), oil on oak panel, The Metropolitan Museum of Art, Robert Lehman Collection (1975.1.110)

A  visit to New York’s, Metropolitan Museum of Art, Old Masters Collection, provides the interested viewer with an opportunity to look closely at pictures painted on wooden panel, canvas, and occasionally, stone or metal. Here, we will refer to their collection and concentrate on the materials, techniques and physical history of European works from north of the Alps, with an eventual detour to Italy, which will be the subject of Part II of this article. The paintings being considered during the 15th-17th century belong to the genre now classified as “easel paintings” – rectangular in format, enclosed in a frame, and intended to hang or stand upright. Some of the very smallest pictures, especially those with a religious subject, might have been kept in a special box with other treasures. Other small pictures were originally diptychs or triptychs: two or three panels hinged together that could stand open during personal devotion and then be folded for transport or storage. Larger pictures, now all too often framed and presented in museums as separate entities, frequently belonged to multi-part structures – usually three parts or more (the latter referred to as polyptychs) – which functioned as altarpieces placed on or above church altars. Increasingly, as the Renaissance progressed, painters produced paintings with secular themes in single-field format, which also became the preferred form for religious pictures.Painting on wooden panels was a medieval practice that continued through the fifteenth century, although it began to disappear during the first half of the sixteenth century (more rapidly in Italy than in northern Europe). Hardwoods were preferred – oak in the Netherlands, and in other regions lime, beech, chestnut, and cherry among others, depending upon local availability. The fashioning of panels and wooden frames was undertaken by specialists: carpenters with their own workshops who were subject to guild regulations mandating high quality for their products, as were the painters in their guild. The wood was to be well seasoned and quarter sawn into planks, which were then joined with wooden dowels, and extra battens nailed to the reverse if the panel was a large one. The planks were usually aligned vertically if the panel was rectangular in shape. Looking closely at a painting on panel today, one may occasionally see the vertical joints of the planks, especially if a crack has opened along one of these seams. 

Panel supports were eventually supplanted by stretched canvas during the later part of the Renaissance, although for centuries past there had been an active industry producing painted works such as banners and wall hangings, often on linen. The canvas supports of easel paintings, of which there are numerous examples in any museum, were most often stretched onto wooden frames, although they could also be glued to panels. As the sixteenth century progressed, a taste developed for paintings on less traditional materials such as slate and copper. The nature of the support affected the finished appearance of the picture because paint layers tended to be fewer and thinner by then, and painters would exploit the roughness and more matte characteristics of canvas or the smooth and shiny surface of copper or slate. In the case of the latter two, the taste for these supports may have been prompted by their resemblance to the brilliantly opaque surfaces of expensive enamels. 

Christus, Petrus, Portrait of a Carthusian (1446), oil on wood, The Metropolitan Museum of Art, NY, Jules Bache Collection, 1949 (49.7.19)

Painters had been aware for centuries before this, however, that the color, texture and reflectivity of the ground on which they painted would affect the finished appearance of the painting. Panels were primed before the pigment was applied to create a smooth, non-absorbent and brightly white surface. Upon arriving at the painter’s workshop a panel would receive multiple layers of gesso, ground calcium carbonate mixed with glue (the Italian painters typically used calcium sulfate instead). The first layer might be a piece of fabric glued directly to the panel to help hide seams and knots. Canvas was also gessoed, although the layers were much thinner to avoid cracking. By the sixteenth century the gesso layer could be so thin that it lodged only between the interstices of the fabric weave, allowing the texture of the canvas to play a role in the achievement of painterly effects. By this time many painters had begun to tint their grounds by adding pigments to the gesso, with noticeably darker colors by the end of the Renaissance (ca. 1600). One may occasionally see the color of ground priming when tiny cracks – craquelure – caused by various kinds of damage and wear reveal the under layers. 

The next stage was to apply the composition to the prepared surface. Painters often executed highly finished preparatory drawings, which could be transferred by tracing or pouncing – pricking holes along the contours of the drawing and dusting charcoal through the holes onto the gesso ground. A common method of transferring a compositional motif was “squaring”, which allowed the artist to alter its scale while maintaining the desired proportional relationships. Some painters executed freehand sketches directly, using pen and ink, chalk, or a brush dipped in a diluted pigment; and architectural details were incised with a stylus, although this latter practice was more frequent in Italy. One may occasionally see traces of underdrawing if one looks closely, especially where paint layers have become transparent over time. 

By the Renaissance period many painters were making more than one version of their pictures, especially the smaller ones that could be sold on the open market or customized to suit a client’s taste. It was essential to keep detailed preparatory drawings in the workshop for this purpose. In addition to copies or versions of their own work, ranging from studies of individual heads or hands to compositional sketches for large-scale works such as wall paintings. many painters began to answer the demand for copies of works by “famous” artists. This became an important sector of the painting industry throughout Europe, and the copyists, often reputable painters in their own right, would use prints as their source if an original was not close at hand. 

Netherlandish painters were the first to move from the traditional tempera technique to oil, although the two techniques could be mixed in a single painting, with tempera used for underdrawing and for base layers over which oil glazes were applied, or tempera used for lighter-colored areas and oil glazes for the deeper colors. By the end of the fifteenth century the oil technique had spread to Italy and tempera gradually disappeared. Tempera, defined broadly, refers to all water-soluble binders to which pigment is added, but applied to easel paintings, it usually meant pigment mixed with egg yolk. The paint was painstakingly applied by means of small brushstrokes placed side by side with little blending – the various color hues and values were mixed beforehand and kept in separate containers. Tempera produced a hard and rather shiny finish, which was generally quite opaque. 

The early oil technique was based on glazing, whereby pigments were mixed in walnut or linseed oil (sometimes heat-treated beforehand to speed up the drying time), and applied in relatively thin layers that allowed light to penetrate. Light would reflect off the underlayers, including areas of the white gesso ground, and travel back through the veils of colored glazes. In general, while tempera technique worked from dark to light, beginning with the most saturated hue of a pigment in the shadows and adding lighter mixtures for the midtones and highlights, oil glazing worked from lighter underlayers through successive layers of glaze selectively applied to deepen midtones and then to create the deepest shadows. Needless to say, it is virtually impossible to see any brushstrokes – the painter’s application of paint is entirely hidden. Glaze layers are the first to disappear if a painting undergoes any surface damage, which can alter the hues and color relationships. 

Metsys, Quentin (ca.1466-1530), The Adoration of the magi (1526), oil on wood, The Metropolitan Museum of Art, NY, John Stewart Kennedy Fund,1911(11.143)

Fifteenth century painting technique in northern Europe, most especially in Flanders, was based on the reproduction of minutely-observed details of the material world and on the play of shadow and highlight that enabled the viewer to perceive them. Looking closely at a fifteenth century Flemish painting will reveal the painting of individual strands of hair, the highlights on the tiniest pearl or the transparent sparkle of a drop of water . By the sixteenth century, however, many painters were exploring other possibilities offered by an oil-based technique. In addition to exploiting oil’s translucency, they were experimenting with its opacity and malleability, building up highlights with thick daubs of pure pigment – impasto – and dragging and scumbling small amounts of pigment with a dry brush. The resulting picture surface can be rough and three-dimensional in places when viewed close up, yet from a distance the effects are optically convincing and often quite spectacular. This painterly approach was championed from the sixteenth century on by such famous painters as Titian, Rubens and Rembrandt and, in the nineteenth century by Corot and Degas, among others. 

The pigments used by European painters, north and south of the Alps, changed very little until the invention of synthetic pigments in the eighteenth and nineteenth centuries. Pigments were derived from inorganic materials, mostly minerals, that often had to be refined or synthesized with other ingredients to produce colorants such as red and white lead, vermilion, lead-tin yellow, the blues of azurite and lapis lazuli, various colored “earths”, and copper greens. Other pigments were derived from organic sources: black from burned wood, oil or bone; greens, yellows, reds and blues from plants or insects. The latter often produced highly prized red dyes that were turned into pigments by extracting the color from previously-dyed fabric. Gold, silver and tin were all used to highlight details such as crowns, swords and embroidery, and especially for elements that were intended to radiate sacred light such as haloes. Gold was the most expensive and the preferred choice. Gold coins were beaten into thin sheets which could then be cut to various sizes and applied, or the gold could be shredded, mixed with a binder and applied with a brush. One often sees a reddish-brown color showing through damaged areas of applied gold leaf. This is a clay called “bole” that was the preferred ground on which to adhere the gold. Its red hue gave the gold an extra fiery glow, and it formed an extra cushion when the gold areas were “tooled”, that is, designs were gently pressed into the leaf with small stylus-like implements bearing geometric shapes on their tips. The taste for using real gold in paintings slowly fell out of fashion. By the sixteenth century the optical effects of metals, jewels, and even rays of light were created with white and yellow paint instead. More value was placed on the painters’ skill at creating optical illusions than on the presence of the real material. 

Framing was the last step in the production of a painting. By the Renaissance period the frame was usually the responsibility of the painter even if he subcontracted the actual construction to a carpenter or sculptor. Frames were often gilded or painted, sometimes with a special technique intended to imitate colored marble. The elaborate frames for large altarpieces in the late Middle Ages and early Renaissance constituted a substantial part of the cost of the finished product, but as picture formats were simplified into the single-field, rectangular format, frames became considerably less important and often considerably less expensive than the image framed. The frames that presently surround older pictures are rarely original. It is only very recently that frames have themselves become objects of study and hence valued. For centuries, pictures were removed from their frames and re-framed according to the prevailing taste. This was easy to do with canvasses and panels with separate frames, but many early panels, particularly small ones that were originally parts of multi-part altarpieces, were constructed with integral frames, either carved from the same wood as the plank or molded out of gesso (often applied over pieces of wood molding nailed to the planks). These framed fragments are ubiquitous in museum holdings of late Medieval and early Renaissance pictures, and are invariably hung as separate and discreet works of art, having lost their original context entirely. 

Looking closely at pictures on museum walls provides us with glimpses of the process by which painters created their works. It also shows us how closely and carefully these painters regarded the world around them and sought to capture its appearances, including, one could argue, even the phenomenon of sight itself. Despite the damage caused by centuries of wear and aging, it is a tribute to the skill of their makers that these objects have survived as long as they have and still retain the capacity to amaze us. 

by Louisa Matthew- Contributing Writer