Azure painting technique in oil painting Automatic translate

Glazing is a method of layering translucent paints over a dried base. Light penetrates the thin transparent layers, reflects off the layers below, and returns to the viewer, creating the effect of an inner glow. This technique achieves a depth of color and luminosity unattainable by directly mixing pigments on a palette.

The glaze method is based on optical color mixing. When an artist applies a blue glaze over a yellow underpainting, the viewer perceives green, but this green has a unique vibrancy and depth. The pigments do not physically mix with each other — each layer maintains its own identity, interacting with light independently.

Historical roots of the method

The technique of azure painting developed with the advent of oil binders in 15th-century European painting. Until then, artists worked primarily with tempera, which dried too quickly to create the thinnest transparent layers. Oil paints allowed for extended working times and the creation of exceptionally thin layers.

Jan van Eyck was one of the first artists to systematically use glazes in oil painting. His works demonstrate unprecedented transparency and detail. Flemish artists of the 15th century developed a multi-layered system in which the drawing was transferred to a prepared board, coated with imprimatura, then a monochrome underpainting was applied, and only then were colored glazes applied.

Van Eyck used drying oil with added lead and protein components, likely egg white. This emulsion prevented the yellowing and cracking typical of pure oils. For the finest details and expensive pigments like ultramarine, he used tempera to avoid the greenish tint from yellowed oil. Glazes were applied extremely thinly — each layer contained a minimal amount of pigment in pure drying oil.

Venetian school and colorito

16th-century Venetian masters, especially Titian, developed the technique of glazing to a virtuoso level. Venice, as a trading center, had access to high-quality oriental pigments. Titian employed the concept of "colorito" — the priority of color over design. His method involved applying dozens of ultra-thin layers of transparent pigment dissolved in oil or resin.

Titian worked in groups of colors: first he applied transparent yellow glazes, then red, then black. The final layers were created with translucent paints called velaturas, in which the pigment was mixed with white in equal proportions. Even opaque pigments like Venetian red and black became transparent when diluted with sufficient binder.

The Venetian color palette was characterized by warm, luminous tones — deep reds, golden yellows, and rich blues. Layered glazes created a jewel-like effect. This Venetian approach contrasted with the more linear, sculptural style of the Florentine masters.

Baroque and Rembrandt’s Innovations

Rembrandt expanded the possibilities of the glaze technique by combining it with impasto — a thick, impasto painting technique. He applied thick layers of white in the highlights, allowed them to dry, and then covered them with transparent yellow and brown glazes. Light, passing through the transparent layer and reflecting off the raised white, created a golden glow.

For this method, Rembrandt used two types of white. The first, for impasto, was quick-drying and possibly laced with egg or crushed glass. The second, for smooth areas, consisted of high-quality lead white ground in heated linseed or walnut oil. Impasto white was very thin, containing a minimum of binder.

Rembrandt added chalk and ground glass to his glazes. The chalk acted as an inert pigment, transparent in oil. The glass likely contained lead or cobalt and accelerated drying. These additives gave the glaze layers body while maintaining their transparency.

Physical basis of transparency

The transparency of glaze is determined by the interaction of light with pigment particles and the binder. The key parameter is the refractive index (RI), a value that characterizes a material’s ability to refract light rays.

When the refractive index of a pigment is close to that of the binder, light passes through the paint layer with minimal scattering. Linseed oil has a RI of approximately 1.48. Pigments with similar values — phthalocyanine blue, quinacridone red, and transparent iron oxide — transmit light efficiently. In contrast, titanium white, with a RI of approximately 2.7, causes strong scattering of light, creating an opaque, covering layer.

Particle size also affects transparency. Particles smaller than half the wavelength of visible light (approximately 200 nanometers) cease to scatter radiation effectively and become transparent. This explains why some pigments, such as transparent iron oxides, produce a rich, transparent color despite their high tinting strength.

Pigment volume concentration

The ratio of pigment to binder in a paint film is called pigment volume concentration (PVC). A low PVC means more binder relative to pigment, resulting in a transparent, glossy, and flexible film. A high PVC provides more pigment with less binder, increasing opacity but potentially weakening the film.

When creating a glaze, the artist must maintain an appropriate SAR to ensure light passes through the paint layer efficiently. When pigment particles are spaced apart, light scattering is minimal, and more reflected light is returned from the substrate, creating a translucent effect. Excessive pigment concentration increases scattering and leads to opacity.

Selecting Pigments for Azure Painting

Artists traditionally prefer pigments classified as transparent or low-opacity. Phthalocyanine blues, quinacridone reds, and transparent iron oxides exhibit low light scattering due to their properties. Earth pigments — raw sienna, burnt sienna — often exhibit translucency at moderate opacity due to their specific particle morphology.

Before the advent of synthetic pigments, artists had a limited palette. Ultramarine from lapis lazuli, madder lake from madder, and green from malachite or copper green formed the base. Van Eyck used azurite with lead white in the first layer of blue, overlaying it with pure ultramarine in the second layer. Green was created by applying white with charcoal, then white with copper green, and the final glaze was copper resinate.

Contemporary artists have access to a wide range of transparent synthetic pigments. Quinacridones offer pure reds, violets, and magentas. Phthalocyanines produce vibrant blues and greens. Transparent iron oxides provide red-brown and yellow-brown tones. All these pigments have excellent lightfastness and chemical stability.

Opaque pigments can also be used in glazes if diluted sufficiently with a binder. Titian demonstrated that Venetian Red and Black Mars appear transparent against a light background when mixed with the correct consistency. The key is the ratio of pigment to medium.

Binders and mediums

Linseed oil is a traditional binder for oil painting. It is flexible, forms a durable film when dry, and exhibits acceptable resistance to yellowing. For glazes, linseed oil is used both alone and as part of complex mediums.

Stand oil (polymerized linseed oil) is produced by heating linseed oil in the absence of air. It has a thicker consistency, forms a more durable film, and is less prone to yellowing. Many artists prefer stand oil for final glaze layers. The downside is its slow drying time, requiring patience when working with multiple layers.

Walnut oil dries more slowly than linseed oil and yellows less, making it suitable for light glazes. Poppy seed oil is even lighter but forms a more fragile film. The choice of oil depends on the artist’s needs and the nature of the work.

Complex mediums

Historically, artists created complex mixtures for glazes. The classic recipe included equal parts linseed oil, turpentine, and dammar varnish. Turpentine thinned the mixture, facilitating the application of thin layers. Dammar varnish increased the refractive index, enhancing transparency and imparting gloss.

Modern ready-to-use mediums like Liquin or Galkyd offer convenience and predictability. They contain alkyd resins, which accelerate drying and improve paint flow. Alkyds provide greater transparency, flexibility, and reduced yellowing compared to natural resins.

Venetian turpentine (larch resin) was used by old masters to impart elasticity and shine. A mixture of one part linseed oil, one part turpentine, and one part Venetian turpentine creates a smooth working medium. Spike oil (lavender oil) served as a less toxic alternative to turpentine.

The fat-on-thin rule

The fundamental principle of oil painting — the "thick on thin" rule — is especially relevant when working with glazes. "Thickness" is determined by the oil content of the paint layer, not its thickness. Each subsequent layer should contain more oil than the previous one to prevent cracking.

Paint straight from the tube contains a moderate amount of oil. Underpainting is usually done with thinned paint — with the addition of solvent, which thins the mixture. After drying, thicker layers are applied over the top, adding oil or an oil-based medium. Glazes, consisting primarily of oil with a small amount of pigment, are very oily.

If you apply a thin layer over a thick one, the top layer will dry faster and begin to shrink while the bottom layer is still curing. This creates tension in the film, leading to cracks. Following the thick-on-lean rule ensures the mechanical integrity of the painting for decades.

When working with multiple layers of glazes, it’s not necessary to strictly increase the thickness of each layer, as long as all layers contain sufficient oil binder. The main thing is to avoid applying very thin layers over thick ones. Moderately thick glazes can be layered sequentially without issue.

Preparing the base

The quality of azure painting depends largely on the preparation of the surface. Traditionally, wooden boards were used — oak in Flanders, poplar in Italy — treated with animal glue and coated with a ground of chalk or gypsum mixed with the same glue. The smooth white surface reflected light back through the layers of paint, enhancing the luminosity.

Contemporary artists work primarily on primed canvas. Acrylic primer provides a stable, white base with good adhesion. Some prefer traditional glue chalk primer on canvas, which produces a more absorbent surface, reminiscent of the boards of the old masters.

Imprimatura

Imprimatura is a thin transparent or translucent layer applied over a white ground before painting. It serves several functions: it creates a color base for the composition, reduces the brightness of the white ground, and facilitates the assessment of tonal relationships. Flemish masters used imprimatura in gray or brownish tones.

Imprimatura can be single-color or vary across the canvas. Warm ochre imprimatura is suitable for portraits and figures, while cool gray is suitable for landscapes. Some artists tint sections of the future composition with different colors, anticipating the final palette.

Monochrome underpainting

Grisaille — a monochrome underpainting in shades of gray or brown — combines perfectly with the glaze technique. The artist focuses on chiaroscuro modeling, developing the three-dimensional form of objects without regard for color. Color is added later with glazes.

Grisaille is typically executed in gray tones (based on black and white) or brown tones (based on umber or sienna). The former provides a neutral base, while the latter provides a warm one. The underpainting must be carefully constructed in tone, as it determines the chiaroscuro structure of the finished work.

The lower layers of grisaille contained more lead white, making the paint semi-opaque. The upper layers became more transparent. This created smooth transitions of light and shadow. After the underpainting had completely dried, the artist applied colored glazes.

Colored underpainting

An alternative to grisaille is colored underpainting. Instead of monochrome, the artist lays down the main color masses in a semi-opaque manner, then enriches and deepens them with glazes. This method provides more direct control over the final color scheme.

The Flemish technique meant that the underpainting usually contained hints of the final color, but in a lighter, grayer form. Blue draperies began with a layer of blue and white, red ones with a pinkish one. The final glazes transformed these muted colors into rich, pure tones.

Technique of applying glazes

Preparing the azure mixture begins on the palette. The artist takes a small amount of transparent pigment and mixes it with a medium until it reaches a syrupy consistency. The paint should flow freely from the brush, but not be completely runny. Getting the right consistency requires practice and experimentation.

Some artists recommend first lightly squeezing the pigment onto the palette, removing excess oil, and then adding fresh medium. This gives greater control over the pigment-to-binder ratio. Others work directly with the paint from the tube, thinning it with medium.

Application is done with a soft brush — often squirrel or sable — using long, smooth strokes. The glaze is spread evenly over the surface in a thin layer. Excess paint is removed with a clean brush or lint-free cloth. The goal is to create the thinnest possible coating that allows light to pass through.

Local azures

It’s not necessary to cover the entire surface of a painting with glaze. Glaze is often applied locally, to specific areas that require enhanced color or depth. For example, an artist might apply a warm brown glaze to the shadows of a landscape, leaving the highlights untouched.

Localized application allows for complex color effects. Blue azure on a yellow underpainting produces green, while red azure on the same yellow produces orange. By varying the underpainting and the color of the azure, the artist achieves a variety of shades. This optical mixing method produces purer, more vibrant colors than mechanical mixing on a palette.

Multiple layers

Old masters applied multiple glazes — sometimes up to 20-30 layers. Each layer had to dry completely before applying the next. The effect was cumulative: each glaze deepened the tonal complexity and intensified the sense of luminosity. Patience became essential.

Jan van Eyck likely spent months on a single panel, applying dozens of extremely fine layers. Each layer was so thin that it was barely noticeable individually, but together they created exceptional depth and richness. This labor-intensive process explains why Flemish masters produced relatively few works.

Titian used a different sequence — alternating colors. Yellow azure, then red, then yellow again, then red again. Each new layer modified the hue, creating iridescent, shifting tones. This method required an intuitive sense of color and experience.

Velatury

Velatura differs from glaze in that it is translucent rather than completely transparent. The pigment is mixed with white before adding the medium, creating a milky, hazy effect. Velatura is used to soften contrasts, create atmospheric effects, and model halftones.

Titian completed his works with velatures after a series of transparent glazes. He mixed opaque pigments with white in equal proportions, diluted them with a medium, and applied them in thin layers. This created a soft glow, different from the bright shine of pure glazes. Velatures are especially effective in light areas, softening sharp transitions.

Drying time

A critical aspect of glaze painting is the drying time between layers. Oil paint dries not by solvent evaporation, but by polymerization — a chemical reaction between the oil and oxygen in the air. This process takes days or weeks, depending on the layer thickness, the type of oil, the pigment, and the environmental conditions.

Linseed oil dries faster than walnut or poppy seed oil. Some pigments speed up drying (lead, manganese, cobalt), while others slow it down (carbon black). Temperature and humidity also play a role — a warm, dry environment promotes faster drying.

For the glaze technique, the surface must be completely dry to the touch before applying the next layer. Partial drying is insufficient — when applying a new layer, the brush can disturb the sticky base layer, mixing the paints and ruining the transparency. A conservative approach suggests waiting at least three days, and for thick glazes, a week.

Drying accelerators

Artists looking to reduce waiting time can use siccatives — substances that accelerate the polymerization of oil. Traditional siccatives contain lead, cobalt, or manganese compounds. Modern synthetic mediums like Liquin now include alkyd resins, ensuring drying within 24 hours.

Excessive use of siccatives is dangerous. Drying too quickly makes the paint film brittle and prone to cracking. Siccatives should be used sparingly, strictly according to the manufacturer’s instructions. Natural drying is preferable for the longevity of the painting.

Optical effects

The azure technique creates optical effects unachievable with corpus painting. Light penetrates the paint layer, is repeatedly reflected between the pigment particles, passes to the white ground, and returns to the viewer, carrying information about all layers. This creates the impression of an inner glow, as if the light emanates from within the painting.

Precious stones, glass, water surfaces, human skin — all these materials possess translucency, and azure allows for this quality to be convincingly conveyed. Light passing through the skin interacts with the blood in the capillaries, creating a warm glow. The azure technique mimics this effect by layering warm, translucent tones over a cool underpainting.

Depth is another advantage of glazes. Atmospheric perspective, fog, and haze are achieved through a series of subtle velations that gradually brighten the background. Each layer is barely noticeable, but together they create a convincing illusion of space and distance.

Working with lights and shadows

The traditional formula for oil painting is "transparent shadows, opaque highlights." Highlights are applied in a solid manner, with the addition of white, creating relief and physically reflecting the light. Shadows are painted with glazes, allowing the light to penetrate deep into the paint layer and return muted, creating the impression of a lightless environment.

Rembrandt masterfully applied this strategy. He applied thick white impasto in light areas, sometimes up to a millimeter deep. After drying, he covered these areas with transparent, warm glazes — yellow and brown. Light, reflecting off the textured surface and passing through the colored layer, created a dramatic golden glow.

The contrast between smooth, transparent shadows and textured, azure-covered highlights gave Rembrandt’s works a characteristic liveliness and volume. The painting’s surface became an active element, interacting with light three-dimensionally.

Common mistakes

Excessive pigment concentration is a common problem for beginners. Striving for rich color, the artist adds too much paint to the glaze, causing it to lose its transparency and become opaque. Glazes should be thin enough to appear barely noticeable. Intensity is achieved through repetition, not the thickness of a single layer.

Applying glaze to a surface that’s not yet dry enough leads to the layers blending and a loss of color purity. The sticky underlayer is lifted by the brush, clouding the transparent glaze. Patience is a virtue in this technique. It’s better to wait an extra day than to ruin the work by rushing.

Choosing the wrong pigments is also problematic. Trying to glaze with opaque pigments without sufficient dilution produces a cloudy, opaque result. An artist must know the characteristics of their pigments — their transparency, tinting strength, and refractive index. Experimenting on individual samples helps avoid disappointment in the final work.

Problems with mediums

Excess oil in glazes creates the risk of yellowing and cracking over time. The minimum amount of medium required is the best approach. The paint should be diluted to transparency, but not floating in a pool of oil. Experienced artists apply the glaze mechanically, rubbing it into the surface rather than creating a liquid wash.

The use of dammar varnish in mediums is controversial. Dammar improves transparency and adds shine, but over time it yellows, darkens, and becomes brittle. Modern synthetic resins offer greater stability. If an artist prefers historical recipes, dammar should be used sparingly and be prepared for possible changes as the work ages.

Azure in modern practice

Many contemporary artists employ the glaze technique, adapting it to their needs. Some follow a strict Flemish methodology with grisaille underpainting and multiple glazes. Others use glazes selectively, combining them with alla prima (direct painting on wet paper).

Realistic painting especially benefits from the azure technique. Portraits, still lifes, and landscapes with detailed elaboration of form and light demonstrate the depth and luminosity characteristic of the Old Masters. Artists working in this style study the techniques of Rembrandt, Vermeer, and Velázquez, adapting them to modern materials.

Abstract painting also uses glazes to create spatial and color effects. Their multilayered nature creates complex, ambiguous color fields that shift depending on lighting and viewing angle. The transparency of glazes allows one to see the work’s history, with previous layers showing through the final surface.

Combination of azure with other techniques

Azure painting is rarely used in isolation. Most artists combine it with body painting, impasto, and alla prima. These combinations expand the expressive possibilities. The Flemish technique involved opaque underlayers with final glazes. Rembrandt alternated impasto and glazes in a single work.

Alla prima — painting in a single session on wet-on-wet — seems the opposite of the slow, multi-layered glaze technique. However, after completing the alla prima technique and allowing it to dry, the artist can enrich individual areas with glazes, deepening shadows or enhancing saturation. It’s a hybrid approach that combines spontaneity and reflection.

Sgraffito — scratching the top layers to reveal the underlying ones — creates interesting effects with glazes. The transparent layer is scratched, revealing a vibrant underpainting in the form of lines or texture. Light passing through the glaze reflects especially vividly from these exposed areas.

Care and preservation

Works created using the glaze technique require careful handling. Thin oil layers are fragile, especially if they contain excess medium. Paintings should be stored in stable conditions — avoiding sudden changes in temperature and humidity, and away from direct sunlight.

The final varnish coat protects the painting from dust, dirt, and physical damage. Varnish also evens out the surface’s gloss and enhances the color saturation. Dammar, mastic, and synthetic varnishes each have their own characteristics. Modern conservators often prefer removable varnishes, which can be removed and reapplied without damaging the painting.

Yellowing of oil is a natural aging process. Linseed oil yellows in darkness, but often fades when exposed to light. Paintings stored in dark rooms may acquire a yellow tint, which partially fades when exposed to light. This property should be taken into account when storing long-term.

Each glaze is a delicate balance between sufficient paint film strength and the necessary transparency. Experienced artists sense this balance intuitively, while beginners achieve it through experimentation and inevitable mistakes. Studying the works of old masters, understanding the materials, and patient practice are the path to mastering this noble technique, which has given the world masterpieces we have admired for centuries.