If this is the case, that the trend towards traditional artists’ materials is related to the renewed interest in figurative art, than Bill Creevy, author and contributing writer to American Artist magazine, may have identified the motivation for this trend. He said, “The advantage to being a figurative artist is that you don’t have to really worry about being in or out of fashion. All you have to worry about is whether you can pull it off.”
This implies that a figurative artist must have skill in order to ‘pull it off.’ The idea of skill in painting has always been associated with the old masters. It is the development of drawing and painting skills that may have stimulated the trend towards traditional artists’ materials.
Fig. 1 Drawing from Life at the Royal Academy, 1808, Pyne, William Henry and Combe, William “Royal Academy,” in The Microcosm of London or London in Miniature (Volume I ed.). London: Methuen and Company. pp. Plate 1.
In this article, we examine what are traditional oil paints, what makes them different from modern colors and what benefits they provide artists today. To understand what are traditional oil paints, we first need to examine how they were made.
During the Middle Ages and the Renaissance, the paint used by artists was prepared in the studio. The painter purchased pigment from apothecaries and apprentices, who also prepared panels and grounds for the master painter, then prepared it for use as paint. To obtain a smooth spreading paint the pigments had to be ground into particles of fairly uniform size. Most pigments were ground as smoothly as possible to improve their color and to make a better flowing paint. The pigment was then mixed with sufficient medium to make an easily workable paint. The recipes or instructions used by painters were handed down from master to pupil. Many survive as manuscripts and printed books, such as Theodore de Mayerne’s seventeenth century notebooks on painting and Cennino Cennini’s fourteenth century treatise, Il Libro dell’Arte.
Fig. 2 A sixteenth-century artist’s workshop with apprentices (right) grinding paint from Color olivi, Colorem olivi commodum pictoribus, Inuenit insignis magister Eyckius, Jan Baptist Collaert after Johannes Stradanus, 1591, Copper engraving by an anonymous engraver, 20.5 x 27 cm. Nova Reporta.
The oil paint used by artists from the fifteenth to nineteenth centuries consisted primarily of pigment and vegetable oil, although sometimes gums, proteins and resins were added for particular passages in a painting. Preparing oil paint involved mixing oil, typically linseed or walnut oil, with pigment that had been previously prepared by merchants or artists’ apprentices. The pigment and oil were mixed on a flat stone slab into a smooth paste with a muller. The paint was then placed into shells for immediate use or in pigs’ bladders for later use.
Fig. 3 The artist’s apprentice (left) is preparing paint on a grinding slab from Emperor Maximilian I in the Artist’s Studio, 1512–16, Woodcut, 219 x 193 mm, From Der Weiss Kunig (Der Weiß Kunig), 1775 edition.
By the late seventeenth century, an area of trade had come into being, the artists’ colormen, who supplied prepared pigments, made brushes, prepared canvases and other items required by the artist. The emergence of the trade may well have been stimulated by the increasing amateur interest in painting. However, most professional painters continued to prepare their own paints, possibly through fear of adulteration of pigments. Unscrupulous suppliers had often been adulterated expensive pigments like natural ultramarine (the pigment made from lapis lazuli) and vermilion with cheap additives.
Effects of Particle Size and Shape of PigmentsBy the early nineteenth century most of the colormen were producing color from traditional pigments, manufactured by traditional methods. Advances in the chemical industry at the close of the eighteenth century and throughout the nineteenth century produced an enormous expansion in the range of pigments. Some of these new pigments made valuable additions to the artists’ color range by providing less expensive alternatives for expensive traditional pigments, for example, artificial ultramarine. For the first time, synthetic pigments were replacing traditional pigments on the artists’ palette. Although natural and synthetic ultramarine are chemically similar, their hues and behavior in paint are remarkably different.
Fig. 4 Semi-precious lapis lazuli stone contains the blue mineral lazurite and accessory minerals.
Fig. 5 Lapis lazuli particle viewed in plain- (left) and cross-polarized (right) light clearly shows its variable composition of the blue mineral lazurite and accessory minerals.
Natural ultramarine consists of the blue mineral lazurite (10 to 50%), a feldspathoid silicate, and usually also contains calcite (white), sodalite (blue) and pyrite (metallic yellow) in the semi-precious lapis lazuli stone. (fig. 4) Other possible constituents are augite, diopside, enstatite, mica and wollanstonite. It is impossible to completely free the lazurite from the other minerals as can be seen in the microphotographs. The fragment of lazurite viewed in cross-polarized light show lazurite as blue and calcite as white patches. (fig. 5) When viewed in plain polarized light, pyrite and other minerals appear as dark spots.
Fig. 6 Natural ultramarine viewed in partially polarized light at 64 times magnification.
Fig. 7 Synthetic ultramarine viewed in partially polarized light at 64 times magnification.
Besides a difference in composition, another more critical difference lies in the pigment particles. The microphotograph (fig. 6) shows the diverse range of particle size and shape of natural ultramarine pigment made from lapis lazuli, while synthetic ultramarine is a collection of very fine, homogenous particles. (fig. 7)
Fig. 8 Malachite pigment coarsely ground (1–150 microns) (left) and finely ground (1-60 microns) (right).
Pigment particles do not dissolve in the paint vehicle but remain as discrete particles. The size and shape of pigment particles greatly influence the consistency and behavior of paint. Pigments in older paintings, in general are coarse, particularly the mineral pigments, compared to pigments in artists’ colors today. Traditional mineral pigments, for example malachite, azurite and smalt, have to be used coarsely ground because, when very finely ground, so much white light is reflected from the surfaces of their particles that they become pale and unsuitable as coloring materials.
The particle size of pigments used by artists’ colormen in the nineteenth century did not change much from previous centuries. According to the archives of Lewis Berger & Company, Ltd., a colorman supplying such firms as Winsor & Newton, the smallest sieves used to screen pigments were 150-mesh. This size mesh retains particles over 104 microns, the smaller particles passing through the screen and presumably sold to paint manufacturers. This is different today where the fine and uniform particle size of modern pigments is largely the result of modern methods of manufacturing pigments.
Fig. 9 Sieves are used to screen out different sized particles.
Mineral pigments, such as azurite, are ground from ores resulting in large, fractured crystals. Grinding a pigment in paint ordinarily does not reduce particle size but merely effects wetting and dispersion of individual pigment particles. Artists’ color makers today do not manufacture the pigments they use in their paint, so they must rely on large industrial firms for their supply of pigments. Pigments intended for paint production are normally supplied in a particle size range such that nearly all pigment particles pass through a 325-mesh sieve.  This sieve size screens out particles larger than 44 microns.
Modern pigments are developed on a quantitative basis for the paint industry, in which producing paints for artists plays an insignificant role. They are formulated for maximum tinting strength, covering power and stability in paint without concern for their chromatic diversity and novel consistency. To achieve maximum desirability in modern paints, pigments are made homogenous in shape, size and composition. For example, to increase the covering power of a pigment, particle sizes are reduced to the smallest possible. The smaller the particles, the more the color nuances of the pigment are absorbed into its basic hue, as in inks that have no texture. Particles that are more consistent in shape and size also tend not to settle quickly and separate from their binder once inside a container. This increases the shelf life and thereby marketability of paint, but does not necessarily increase its desirability as a color for artists.
Fig. 10 Relative size of different particles
To understand the relative size of particles in modern and traditional paints, we can compare it to a common object—typical human hair, which is about 50 microns thick. (fig. 10) A 100-micron particle of a mineral pigment in artists’ colors prior to the twentieth century would be twice the thickness of a strand of hair. The largest particles in modern colors are less than 44 microns, and typically the median particle size is less than 3 microns.
Fig. 11 Natural yellow ocher viewed in partially polarized light at 160 times magnification.
Fig. 12 Synthetic yellow iron oxide (Mars Yellow) viewed in polarized light at 160 times magnification.
The difference in particle size is not confined to rare, mineral pigments. Yellow ocher is a pigment that has been on every artist’s palette of every period in history. And although it is still widely available, the trend in recent years has been to replace it with artificial yellow iron oxide while still naming the artists’ oil color yellow ocher. The difference between the two pigments is more than its composition, the microphotograph of yellow ocher shows particles of heterogeneous size and shape (fig. 11), while particles of yellow iron oxide are very uniform and fine (fig. 12). The particle size distinction creates paint with very different properties.
The difference between modern and traditional artists’ colors provided by the particle size and shape of pigments cannot be more appreciated than with lead white. Lead white is the most important white pigment in history. It is one of the earliest pigments to be made artificially, known to the Egyptians, ancient Greek artists used it in painting and the Roman historian Pliny described how to prepare it. Its method of manufacture did not changed significantly since Pliny’s description of it in the first century before the Common Era until the beginning of the twentieth century.
This method known as the “Old Dutch method” or “stack process” consists of placing lead strips or castings in earthenware pots containing a small amount of vinegar. The pots are placed in layers of horse dung and left for up to three months. As the dung decomposes it releases heat, water and carbon dioxide, the essential ingredients in making lead white or basic lead carbonate. After some time the lead is corroded and the result is a white pigment that flakes off the metallic lead. Since the early twentieth century, the process of making lead white radically changed to what is called the “quick process.” (For a detailed description of the Old Dutch method of lead white, see the article, Stack Process White Lead—Historical Method of Manufacture.)
Fig. 13 Cross-section of modern lead white paint layer made with scanning electron micrograph (SEM).
Fig. 14 Cross-section of stack process lead white paint layer made with scanning electron micrograph (SEM).
The Old Dutch method and the quick process both result in lead white (basic lead carbonate), but with different particle sizes and shapes. The next two images are cross sections of lead white paint; the first of (fig. 13) modern lead white pigment; and the second (fig. 14) lead white pigment of the eighteenth century made by the stack process. The scanning electron microphotographs (SEM) show the particle shape and size of modern lead white pigment and the crystalline structure of stack process lead white.
The difference of the particle size and shapes of pigments in traditional and modern oil paints result in different properties also known as “rheology.” To help us understand the differences, we should first define common terms used to describe paint rheology. Paint is a “pseudoplastic,” hence its behavior is both similar to a liquid and a solid when force, such as stirring or brushing, is applied to it.
When the viscosity of a pseudoplastic substance decreases with increasing force, this is called “shearing thinning.” An example of a shear thinning substance that we are all familiar with is ketchup. If the viscosity increases with increasing force we call this “dilatant” or “shear thickening.” A commonly known dilatant substance is starch. When the viscosity of a substance decreases over time at a constant rate of force, this is called “thixotropy” and the substance is said to be “thixotropic.”
The particle size and shape of lead white pigment changes the paint’s properties and its behavior when brushed. This is clearly demonstrated in the video clip of two samples of lead white oil paint. The paint on the right is modern lead white, while the pile of paint on the left is made with stack process lead white. When brushing thixotropic paint it flows, when stopped it holds it shape. The particle size and shape of traditional pigments often provide thixotropy.
Modern artists’ colors contain uniform and very fine pigment particles. Traditional artists’ oil paint, on the other hand, typically contains larger particle sized pigments in a variety of sizes and shapes. Although modern pigments have a variety of particle sizes and shapes, these are far simpler shapes and are smaller and more homogeneous than traditional pigments.
Fig. 15 Influence of the particle size and shape of pigments on the opacity, tinting strength and hue of paint.
The particle size and shape influences the covering power of the paint, its tinting strength and color. For example, the small, uniform particles of modern paints provide more coverage and higher tinting strength. The larger particle size and heterogeneous shapes of traditional pigments are typically more transparent, allowing more light to pass through the layers of paint to be reflected from the ground thereby increasing its apparent luminosity. (See the bottom illustration of fig. 15.)
The small, uniform particles of modern pigments have greater tinting strength and purer color. Traditional pigments, however, offer the artist diverse chromatic diversity due to the heterogeneous size and shape of the particles. For example, crystalline hematite of about one micron size has a distinct violet tint differing from the bright red color of hematite with sub-micron particles.
Advances in Paint TechnologyAdvances in technology not only changed the pigments used in oil paint, it changed how these paints were manufactured. In the nineteenth century, machinery was developed specifically for colormen. James Rawlinson’s hand-operated, single-roll grinding mill was commended in 1804 by the Royal Society of Arts in London for the preparation of artists’ paint. The development of powered mills made it possible for artists’ colormen to increase paint production, thereby lower the cost of paint while producing smoother pastes. The development of the collapsible tube in 1841 permitted colormen to supply oil paint in this convenient form to artists. It also allowed paint to be stored for longer periods of time.
Fig. 16 Rawlinson’s single-roll grinding mill for making artists’ colors.
By the twentieth century, pigment wetting, dispersion and stabilization in paint binders were better understood, which lead to the use of additives that greatly changed the manufacture of paint. For example, the addition of aluminum stearate to artists’ oil paint in the early twentieth century has become a common additive found in nearly all artists’ oil paint today. While helping to prevent pigment and oil from separating, such additives altered the consistency of oil paints once familiar to artists prior to the twentieth century.
With increasing amounts of aluminum stearate the oil pigment mixture becomes viscous, and by using an appropriate amount of aluminum stearate the paint can gel using a lower pigment concentration. This greatly mitigates or entirely eliminates the effect that individual pigments have on the consistency of paint.
ConclusionTraditional paint made with traditional pigments result in paint with chromatic diversity. The heterogeneous size and shape of traditional pigments gives novel, unique behavior to oil paint. Modern additives alter the behavior of paint, reducing or eliminating the individual effects created by pigments, and granular, crystalline pigments give a certain pleasing quality to paint films that cannot be had from fine, well-dispersed pigments such as are produced for the modern paint industry.
This is the transcript of the lecture given by George O’Hanlon at the College Art Association 100th Annual Conference in Los Angeles on February 24, 2012.
Rublev Colours Artists’ Oils are Traditional Oil PaintsWhy are Rublev Colours different from other modern commercial oil colors? One reason is that we use natural pigments or historical reproductions of pigments used by the old masters. Another reason is that we make Rublev Colours Artists’ Oils as they did before modern tube colors—without additives. Rublev Colours Artists’ Oils are formulated to maintain the unique characteristics of each pigment in oil. The character found in each tube of our oil colors is unique due to the pigment inside, giving the artist nearly limitless choices of texture, opacity, consistency, tone and hue. With Rublev Colours you experience the transparency of yellow ocher, the pale coolness of green earths, and the crystalline glitter of deep blue azurite.
The particles of natural pigments are at least six times the diameter of most synthetic pigments in modern artists’ colors. However, when we remember how largely crystalline or semi-crystalline pigments, such as azurite, malachite, lazurite, and so on, were used in old masters’ paintings, it is easy to understand how these beautiful surfaces with broken lights were obtained. An examination, for instance, of the surface of azurite blue under the microscope at once reveals the beautiful mass of blue and blue-green crystals, reflecting light in all directions, and thus of course enhancing the decorative effect.
Pure Oil Color, No AdditivesRublev Colours Artists’ Oils do not contain additives, such as fillers, driers and stabilizers—simply pigment and oil. We use refined linseed oil in our paint sometimes with a small amount of heat-bodied linseed oil. Stabilizers, such as stearates and waxes, are not added that diminish the individual effects of pigments in oil. Therefore, you will find different consistencies from color to color due to the individual pigment characteristics, and an occasional bit of free oil. Some colors brush out long, others short and buttery and still others are thixotropic.
Overall, Rublev Colours Artists’ Oils have longer brushing consistency than most tube colors available today, making them ideal for both bristle and soft-hair brushes in fine rendering, old master-like effects, on both canvas and panels.
Lear more about Rublev Colours Artists’ Oils
Notes Gettens, Rutherford John and Stout, George Leslie, Painting Materials: A Short Encyclopaedia, Dover Publications, 1966, p. 146.
 Kirby, Jo; Spring, Marika; Higgitt, Catherine, “The Technology of Eighteenth and Nineteenth Century Red Lake Pigment,” National Gallery Technical Bulletin, Vol. 28, p. 72.
 Patton, Temple C., Paint Flow and Pigment Dispersion, Interscience Publishers, 1964, p. 207.
 Hradila, David; Grygara, Tomáš; Hradilová, Janka; Bezdičkaa, Petr. “Clay and iron oxide pigments in the history of painting.” Applied Clay Science 22, 2003, p. 230.
 James Rawlinson, Transactions of the Society, Vol. xxii, 1804, p. 260–264. “Rawlinson’s Colour Grinding Mill,” Mechanic’s Magazine, Vol. 6, No. 152, Knight & Lacey, 1827, pp. 177–174.
 Tumosa, Charles S. “A Brief History of Aluminum Stearate as a Component of Paint,” WAAC Newsletter 23(3), 2001, pp. 10–11.