Oil Painting Techniques:
From Giotto to Raphael

The transition from medieval to Renaissance painting techniques is one of the most exciting periods in art history. The period between the late 13th century, when Giotto began his first frescoes, and the early 16th century, marked by the works of Raphael, was a time of radical experimentation with materials and methods. Artists gradually abandoned egg-yolk tempera in favor of oil paints, which opened up new possibilities for conveying light, volume, and spatial depth.

Giotto and the Tempera Tradition

Giotto di Bondone worked primarily in fresco and tempera, the techniques that dominated Italian painting during the Trecento. Frescoes were created using the buon fresco method, in which pigments were applied to fresh lime plaster. The process of carbonating the lime required precise timing. Each section of the fresco, called a giornata, had to be completed in a single day, while the plaster was still wet.

Some pigments couldn’t withstand the alkaline environment of fresh lime. Ultramarine and azurite-based blues, copper green, red lead, and varnish paints were applied over dried plaster using the a secco method. Casein, milk, or egg yolk were used as binders. These additional layers were less durable and often deteriorated over time, altering the original appearance of the works.

Preparing wooden panels

When working on wooden panels, 14th-century artists followed a complex process of preparing the base. Cennino Cennini describes this method in detail in his treatise "Book of Art." Wooden boards were joined and reinforced with strips of linen cloth soaked in glue (impannatura). Then, seven to eight layers of gesso — a mixture of gypsum and animal glue — were applied.

The surface was carefully sanded to an ivory-smooth finish. The design was transferred with willow charcoal, then fixed with a light wash of ink. An alternative method was pouncing — a technique in which the outline of the design was pierced with an awl on paper and then transferred to a prepared panel using charcoal powder.

Gilding and decorative elements

Gilding was done before painting. The outlines of the future gilded areas were scratched with a sharp stylus on the prepared surface. A layer of bolus — red Armenian clay — was applied beneath the gold leaf, imparting warmth to the gold and facilitating polishing.

Cennini recommended gilding on damp days. The bolus was moistened with a mixture of water and a small amount of egg white, then a very thin sheet of gold was applied, slightly overlapping the previous one. After drying, the gold was polished with an animal’s tooth to a mirror shine.

An alternative technique, a missione (glue gilding), used oil-based gilding. Cennini describes a mixture of boiled linseed oil, lead white, and a variable amount of copper verdigris to speed drying. Garlic juice mixed with a small amount of lead white and bolus was sometimes used. Varying the mixture allowed for varying the time between applying the gilding and the adhesion of the gold, as well as controlling the luster of the surface.

Technique of applying paints with tempera

The pigments were ground on a glass plate with distilled water until smooth. The powder was then mixed with egg yolk as a binder. Cennini prescribed preparing the paints in small vessels, creating gradations from dark to light tones.

The painting began with the background elements — the figures’ clothing and architectural details. "Begin by applying a dark color, forming folds… then take a medium tone and place it on the projections and backs of the dark folds. Then take a light color and place it on the reliefs and backs of the illuminated part of the figure." This method of successively layering tones was repeated many times until the desired volume was achieved.

Working on the faces required a special technique. First, a translucent greenish underpainting (verdaccio) of terre vert and lead white was applied. The main drawing showed through this layer. Over this green tone, pinkish brushstrokes of cinnabar and lead white were applied to the cheeks and lips. Flesh tones were created using hatching (tratteggio) from light to dark, then merging the shades, with the green underpainting remaining slightly translucent.

Transition period: experiments with binders

In the late 15th century, Giovanni Bellini began to employ new techniques that served as a bridge between pure tempera and oil painting. He used an emulsion of egg yolk and oil (tempera grassa) and a mixed technique in which layers of tempera were alternated with layers of oil.

Bellini applied an oil ground made of lead white instead of the traditional glue, which enhanced the brightness and depth of the paint layers. The presence of lead facilitated the polymerization of the drying oil. The artist created colored grounds depending on the subsequent paint layers, allowing him to control the optical effects.

The pictorial layer reached considerable complexity — up to four overlapping layers, but with simple pigment mixtures, no more than two in a single composition. Bellini continued to follow the principles of tempera, exploiting the luminosity of the underlying layers, but gained new possibilities thanks to the oil binder.

Northern Influence: The Discoveries of Jan van Eyck

Jan van Eyck did not invent oil painting, but he refined it to such an extent that his contemporaries perceived his achievements as revolutionary. Flemish masters of the early 15th century learned to purify and lighten oils and resinous varnishes to a high degree of transparency. This allowed for the application of complex glazes without losing the vibrancy of the underpainting.

Van Eyck’s technique relied on multiple layers of ultra-fine transparent glazes. The slow drying of oil paints allowed time for meticulous detailing and reworking. The glazes created an effect similar to stained glass — red glass reveals its full color intensity only due to the light passing through it.

Layering one color over another dried layer produced a more vibrant result than directly mixing the pigments. The violet tone, obtained by directly mixing blue and red, lacks vibrancy, but gains luminosity when applying red glaze over a dried blue layer. All paints acquired a softer and more saturated sheen compared to pure tempera.

Multilayer construction method

Van Eyck developed a system in which each section of the painting went through several stages. First, a detailed underpainting was completed, defining all forms and the chiaroscuro modeling. Then, glazes and scumbles were applied successively, allowing for control over the final appearance of the work and creating subtle transitions of color and light.

This technique was slow and painstaking, allowing for no improvisation. Each section of the painting required multiple iterations to achieve the final effect. The constant layering of glazes sometimes gave the finished work the appearance of individual fragments, carefully painted and meticulously assembled — an effect reminiscent of tempera painting.

Masaccio and the Early Florentine Renaissance

Masaccio was the first great artist of the Florentine Quattrocento to introduce new principles of depicting space and volume. He was influenced by Giotto’s achievements in conveying the materiality of forms and naturalism, as well as Brunelleschi’s formalized application of perspective in architecture and sculpture.

Masaccio was the first to consistently apply linear perspective with a single vanishing point in his frescoes in the Brancacci Chapel. The chiaroscuro technique — a strong contrast of light and shadow — allowed for the modeling of figures and the creation of a sense of volume and depth. Directional light cast shadows and created highlights, enhancing the three-dimensionality of the depicted world.

Masaccio’s approach was radically different from the Gothic and Byzantine traditions, which favored flat, stylized forms and golden backgrounds. His paintings were distinguished by a strong sense of three-dimensionality, achieved through the use of linear perspective and chiaroscuro. The illusion of space was enhanced by the use of foreshortening and overlapping forms.

Leonardo da Vinci and the sfumato technique

Leonardo da Vinci developed a painting method that became the pinnacle of Renaissance technique. His innovative approach combined profound anatomical knowledge with experiments in optics and materials. The artist not only studied the structure of the human body but also explored how atmosphere influences the perception of forms and colors.

Principles of sfumato

The term "sfumato" comes from the Italian fumo (smoke) and describes a technique for creating soft, smoky transitions between tones and colors without hard edges. Leonardo wrote that "light and shadow should blend without lines or boundaries, like smoke." This technique allowed for unprecedented realism, especially in the depiction of skin, eyes, and atmospheric effects.

Sfumato was created by applying multiple, ultra-thin, transparent layers of oil paint. Leonardo carefully blended the layers with brushes or sometimes even his fingers to completely eliminate visible lines. The result was forms that seemed enveloped in soft light or mist.

The method required exceptional patience. Some of Leonardo’s works took years to complete, as each layer had to dry before the next was applied. The Mona Lisa and the Madonna of the Rocks demonstrate the perfection of this technique, with the sitters’ faces possessing an enigmatic softness and psychological depth.

Anatomy and painting technique

Leonardo’s profound knowledge of human anatomy informed every brushstroke. Sfumato became a tool for reproducing the translucency of skin by layering paint to mimic its structure. Soft transitions revealed the underlying musculature without harsh lines, and subtle modeling around facial features added depth to expressions.

Leonardo developed a system of successive layering of hues. He blended multiple tones, gradually layering them and manipulating their saturation. The gradual reduction in color intensity created the illusion of distance or softness. This technique allowed him to convey the complexity of flesh tones, fabrics, and backgrounds with astonishing realism.

Materials and experimental methods

Leonardo favored oil paints for their slow drying time and blendability. He experimented with various oil mixtures to achieve the ideal drying time and transparency. Glazing paints included linseed oil and resins, which controlled the transparency of the layers.

Studies of samples from the Mona Lisa revealed a unique mixture of highly saponified, high-lead oil and cerussite-depleted lead white. Most notable was the presence of plumbonacrite (Pb₅(CO₃)₃O(OH)₂), a rare compound stable only in alkaline environments. Leonardo likely treated the oil with a high concentration of lead oxide (PbO) to produce a thick paint suitable for covering wood panel.

Analysis of fragments of The Last Supper confirmed that Leonardo’s palette contained not only lead oxide in the form of litharge (α-PbO) and massicot (β-PbO), but also plumbonacrite and chanonite (Pb₂OCO₃). The latter phase was discovered for the first time in historical painting, demonstrating the experimental nature of the artist’s techniques.

Leonardo used fine brushes made of mink or squirrel fur, as well as unconventional tools such as soft fabrics, feathers, and fingertips for blending. This innovative use of materials contributed to the effectiveness of sfumato and opened up new artistic possibilities.

The Venetian School and the Development of Oil Painting

In the Venetian milieu of the 16th century, painting acquired a richness of impasto overlays, distributed without preliminary drawing, using the glaze technique. Titian Vecellio worked almost exclusively in oil, which at the beginning of his career was a relatively new technique in Italy, where tempera and fresco remained the dominant methods.

Titian technique

Titian’s pictorial layer consisted of numerous layers of oil paint, often without apparent logic. Stratigraphies obtained from micro-samples show the superposition of ten to twelve successive layers. The slow drying of oil paints allowed the artist to build a series of glazes and accurately convey the appearance and texture of the human body with a new delicacy and softness.

Titian applied light, transparent layers of oil paint one on top of the other, creating a wealth of color nuances. This method allowed for effects unattainable with direct painting. Venetian masters exploited the ability of oil paints to create depth and luminosity through multi-layered constructions.

Titian’s mastery of the nude female body is particularly noticeable, often possessing a sensuality unusual for the time. The slow drying of oil allowed for the modeling of forms with a precision unattainable in tempera. The artist could return to sections of the painting several days later and adjust the subtlest nuances of tone and color.

Refusal of preliminary drawing

Venetian painters gradually moved away from the Florentine tradition of detailed preparatory drawing. The oil technique allowed for the freedom to alter the composition as the work progressed. The paint remained wet long enough to allow for reworking the surface. Tempera dried very quickly, while fresco required working on wet plaster and did not allow for reworking.

This flexibility radically transformed the creative process. Artists were free to improvise, respond to random effects, and experiment with color combinations. Venetian painting acquired a painterly quality and coloristic richness that contrasted with the linearity of the Florentine school.

Raphael and the synthesis of Renaissance technique

Raphael Sanzio represents the pinnacle of Renaissance painting. He synthesized Florentine precision of drawing with Venetian coloring and Leonardo’s softness of modeling. His works in the Vatican demonstrate the highest technical mastery and a willingness to experiment with new methods.

Frescoes of the Vatican Stanze

When working on the frescoes in the Vatican rooms, Raphael employed the traditional buon fresco technique, adding a secco for final details and colors incompatible with lime plaster. The compositions were distinguished by their impeccable use of perspective and harmonious color relationships. Raphael achieved a balance between monumentality and grace, between architectural space and human figures.

The artist meticulously planned his compositions, creating detailed, life-size cartoons. The design was transferred to the plaster using a method called dusting or direct transfer through piercing. The work was completed in sections — giornate — each completed in a single day.

Experimental oil painting on the wall

Restoration work in the Hall of Constantine revealed a revolutionary technical discovery. Two figures — the allegories of Justice (Iustitia) and Courtesy (Comitas) — were painted not in traditional fresco, but in oil directly on the wall. Raphael used a base of heated natural resin, applied directly to the wall and held in place by a grid of nails driven into the plaster.

This method allowed for more revisions, more detailed work, and superior color consistency compared to fresco. The technique allowed for longer periods of work on a single section of the painting, allowing for changes after the previous layers had dried. Oil paints on the wall provided richer colors and subtle tonal transitions.

Raphael died in 1520 at the age of 37, before completing the decoration of the hall. His students, Giulio Romano and Giovanni Francesco Penni, continued the work, using only traditional fresco techniques. They made no attempt to replicate their teacher’s method, likely lacking the knowledge to do so. As a result, the two oil figures remained an isolated experiment, forgotten for centuries.

The discovery was made possible by modern scientific methods — infrared reflectography, ultraviolet fluorescence, and color-corrected photography. These tools confirmed that both figures were painted by Raphael himself, using an experimental technique previously unknown at such a level of detail.

Easel painting by Raphael

In his easel paintings, Raphael demonstrated a complete mastery of the oil technique. His portraits and altarpieces are distinguished by the softness of their modeling, the transparency of their shadows, and the luminosity of their local colors. The artist employed multi-layered construction with meticulous underpaintings and subsequent glazes.

Raphael’s color scheme combined the vibrancy of the Florentine school with the richness of the Venetian palette. He achieved a harmony of color relationships, in which each tone supports the overall unity of the composition. His technique allowed him to convey a variety of textures — the softness of skin, the sheen of silk, the weight of velvet, the transparency of a veil.

Evolution of binders

The transition from egg tempera to oil painting spanned a century and a half. Italian artists held tempera in high esteem and were reluctant to abandon the tried-and-true technique. Tempera itself was a medium suitable for complex expression. Frescoes were finished with tempera to achieve a high degree of completion and to utilize colors chemically incompatible with lime.

Tempera grassa — an emulsion of egg yolk and oil — was an intermediate stage. This technique combined the quick drying properties of tempera with the glazing properties of oil paints. Artists gradually increased the proportion of oil in the binder, approaching a pure oil technique.

The highest achievements of Italian Renaissance painting sought to return to a quick-drying, lean medium, similar to tempera but retaining the high viscosity of semi-polymerized oil without the drawback of excessive sliminess. This was a natural progression in technique, necessitated by the need to use raw linseed oil, with its full mucilage content and increased acidity, for grinding pigments.

By the early 16th century, oil had become the primary medium in Italian painting. Artists learned to refine and clarify oils to a high degree of transparency, allowing tempera to be used as a simple underpainting and complex glaze layers without losing their luminosity. This new technique opened up previously unimagined possibilities for conveying light, color, and space.

Pigments and materials

Renaissance artists’ palettes included a limited number of pigments, but they learned to extract maximum expressiveness from them. Lead white (cerussite) served as the primary white pigment and was used not only to highlight tones but also as a base for grounds. The presence of lead catalyzed the polymerization of oil and improved the mechanical properties of the paint layer.

Red pigments included cinnabar (mercuric sulfide) and iron oxide earths. Cinnabar produced a bright scarlet hue but was expensive. Iron oxide earths created warm red-brown hues and were used for underpainting. Blue paints were obtained from ultramarine, mined from lapis lazuli, or the more readily available azurite.

Ultramarine was the most expensive pigment, sometimes costing more than gold. Its vibrant blue color did not fade over time or change when in contact with other substances. Azurite produced a less intense, greenish blue and was prone to blackening. Both pigments were unsuitable for the alkaline environment of fresh lime and were applied a secco.

Yellow tones were created using lead-tin yellow paint and ochres. Greens were obtained by mixing blue and yellow pigments or using copper green, which is prone to discoloration. Black paints were made from charcoal or soot.

Optical effects and color

Renaissance masters discovered the principles of optical color mixing. When a transparent glaze is applied over a dried layer, light penetrates the top layer, reflects off the bottom, and returns to the viewer’s eye, passing twice through the glaze. This effect creates a more intense and luminous color than the mechanical mixing of pigments on a palette.

The glazing technique allowed for color nuances unattainable with direct painting. Artists could adjust the overall tone of a painting by applying thin, transparent layers over the entire composition. Cool, bluish glazes in the shadows enhanced the sense of depth, while warm, golden glazes in the highlights created the effect of sunlight.

Control of the luminosity of local colors was achieved through the brightness of the underpainting. The light ground showed through the translucent paint layers, enhancing their intensity. Dark underpaintings in the shadows created depth and richness in the dark tones. Artists learned to plan the entire layer structure, from the ground to the final glazes, to achieve the desired optical effects.

The influence of technology on artistic expression

The development of oil painting radically changed the possibilities of artistic expression. The slow drying time of oil allowed for the creation of soft tonal transitions impossible with tempera. Artists gained time to meticulously model forms and convey the subtlest nuances of lighting and atmosphere.

The transparency of oil glazes opened up new possibilities for conveying the materiality of objects. Artists learned to imitate the shine of metals, the transparency of glass, the softness of fabrics, and the depth of water surfaces. Each texture required a specific combination of dense and transparent layers, a specific sequence of light and dark tones.

The psychological expressiveness of portraits was enhanced by the ability to convey the subtlest nuances of facial expression. Leonardo’s sfumato technique eliminated harsh contours and created the impression of living, breathing flesh. Soft shadows around the eyes and mouth added mystery and emotional depth to faces.

The spatial depth of the paintings was increased by using aerial perspective. Artists noticed that distant objects appear cooler in tone and less contrast. The oil painting technique made it possible to reproduce this effect, gradually reducing color saturation and contrast as the painting recedes into the distance. Landscape backgrounds acquired an atmospheric and convincing quality.

Workshops and knowledge transfer

Painting techniques were passed down from master to apprentice in workshops through years of practice. Beginning artists spent years grinding pigments, preparing grounds, and performing auxiliary work. Gradually, they gained access to more demanding tasks — transferring the design to the base, working on background elements, and gilding.

Cennino Cennini recommended spending at least six years studying drawing and another six years mastering color under a master’s guidance. Only then could an artist aspire to independent work. This extensive training ensured the transmission of not only practical skills but also aesthetic principles, compositional techniques, and iconographic traditions.

The workshops functioned as collective enterprises. Large commissions were completed jointly by the master and assistants. The master created the composition and worked on the most important elements — the faces of the main characters, the hands, and the foreground draperies. Apprentices executed the backgrounds, the architecture, and the secondary figures.

This system allowed for increased workshop productivity and simultaneously trained the next generation of artists. However, it created a problem of attribution — many works are the result of collective labor, making it difficult to identify the hand of a specific artist. Modern research using technological analysis methods helps us discern the individual styles of artists working on a single piece.

The period from Giotto to Raphael was a time of radical transformation in painting technique. Artists gradually abandoned medieval methods in favor of new materials and techniques that opened up previously unimagined possibilities. The transition from tempera to oil took a century and a half of experimentation, trial and error. The achievements of Florentine, Venetian, and Flemish masters laid the technical foundation for all subsequent European painting. By the early 16th century, oil painting had reached maturity, and artists such as Leonardo and Raphael demonstrated its boundless potential for artistic expression.