[Pigments and Binders]

Vermillion

The name "vermillion" derives from the Latin word vermes, which originally referred to the kermes insect that was used in the preparation of red dye in ancient Rome. Vermillion is closely related to cinnabar, the difference being that "cinnabar" is the term reserved for naturally occurring mercuric sulfide (HgS). Historically the two terms were used interchangeably to designate either the natural or manufactured product. This duality in terminology may have been caused by the fact that the characteristics of the natural and artificially-produced pigments are almost identical. (Roy) The color index number of this pigment is #77766.

 

History of Use by Artists

Vermillion is one of the most opaque pigments used by artists; its lengthy history spans several continents and eras. Since prehistoric times, vermillion has been highly valued by the Chinese and has been used not only in works of art, such as scroll paintings, but in burials and in alchemy experiments as well. (Gettens & Stout) Although it does not appear in the art of ancient Egypt or Mesopotamia, cinnabar was known by the Romans. Pliny recorded that it was so expensive that the government fixed its price.

Despite the fact that vermillion was known in Europe prior to the twelfth century, it was not until this century that the pigment became popular in the arts, especially in manuscript illumination. Its popularization was linked to the growing influence of Moorish science during this period. A new emphasis on experimental chemistry resulted in several new pigments being added to the medieval artist's palette, one of which was vermillion. It was considered the most important medieval pigment made by the direct synthesis of elements. Because of its brilliant hue, vermillion inspired the development of a new palette of rich medieval colors to complement it. The manufacture of the pigment was relatively unknown in Europe before the twelfth century, but was common knowledge by the fifteenth century (see below section on source/manufacture of pigment for more information). (Thompson) Since vermillion was a rare pigment, it was as costly as gilding in the early years of its use, but by the 1400s, it was so commonplace that Cellini Cennino chose not to include a recipe for it in his famous treatise. Renaissance artists considered vermillion one of the most stable and pure-colored pigments. It was the perfect complement to ultramarine and gold leaf.

Vermillion is not used by contemporary artists, because of its unpredictable nature. More consistent and color-maintaining pigments, such as cadmium red, have been developed to take its place in the palette. Despite its recent abandonment, vermillion has been beloved by many centuries of artists and was once one of the most valuable substances in western art.

 

Source/Preparation of Pigment

Vermillion dry pigment

(objective: 20, lighting: 6, substage setting: 1.0, time: 4.5 seconds)

 

 

 

 

 

Vermillion is a red pigment based on artificially produced mercuric sulfide (HgS). Its hues vary from brilliant reds to more purplish tones. The final color corresponds to the amount of grinding it undergoes: the more finely it is ground, the more vivid its hue will be. Three distinct types of mercuric sulfide (vermillion) pigment exist: natural mineral of ground cinnabar (often referred to as cinnabar and not vermillion); dry-process material; wet-process material. (Roy)

The first of these kinds of pigment comes directly from the dense red principal ore of the metal mercury. Cinnabar is common but not abundant around the world. The richest deposits of this ore appear in Spain, Italy, Asia, the Altai, Turkestan, China, and Russia, but other lodes can be found in Germany, Peru, Mexico, California, and Texas. The Almaden mines in Spain were historically and are still today the most important mercury mines in the world. (Gettens & Stout) Historians are uncertain about how long vermillion made from ground cinnabar was used in Europe, or if it was used simultaneously with the synthetic forms of the pigment.

The older of the two methods for manufacturing vermillion is the dry process. According to ancient Latin sources, the Chinese may have been the first to develop this technique in the eighth century AD. Another manuscript from the eighth or ninth century reveals that this technique was also known by a prominent Arabic alchemist. The method (according to later seventeenth-century Dutch sources) involves combining in an iron pan one-hundred parts by weight of mercury with twenty parts of molten sulfur. Following the mixture of the two elements, the compound is transferred to an earthenware pot and then heated to the point of sublimation. At this time, the pot is broken and the red mercuric sulfide is scraped from the inside of the vessel. The product is then treated with an alkali solution to remove all traces of free sulfur. Although originating in Asia, the dry process eventually migrated to Europe, and by the early-seventeenth century, Amsterdam was the center of dry-process vermillion manufacture in the West. (Roy)

The second method of vermillion production is the wet process. This technique entails heating the mercury-sulfur mixture in a warm, caustic solution of ammonium or potassium sulfide. The procedure was invented in Germany in the late-seventeenth century and quickly swept Europe because it was both cheaper and easier than dry process. Pigment manufactured via this method became known as light German vermillion. Its yellowish tone resulted from the relatively low temperatures to which the vermillion was heated. Due to higher firing temperatures, the hue of dry-process pigment was generally darker and cooler than that made in the wet process. The wet process is the only vermillion-making formula used in the West today, but the dry process can still be found in certain parts of China. (Roy)

Chemistry of Pigment

As mentioned above, the chemical formula for vermillion is HgS. It is a stable pigment and is insoluble in weak acids and alkalis. It also does not react with nitric, hydrochloric, and sulfuric acids. Vermillion will react with aqua regia (a mixture of one drop each of nitric and hydrochloric acids); when warmed, the vermillion-aqua regia solution forms opaque white crystals. Several tests for true vermillion exist. One of the easiest, though very destructive, tests is to burn vermillion, which if real, will light up with a bluish flame. (Wehlte)

Although traditionally prized for its brightness of hue, one very negative characteristic of vermillion is its tendency to darken over time. Apparently the ancients were aware of the unpredictability of "vermillion" (naturally-occurring cinnabar), as they observed that it turned black in sunlight. This alteration is somewhat surprising since vermillion is a very stable pigment that is unreactive with other pigments. But the fact remains that passages in paintings often develop dark spots (not large passages of discoloration, only small ones). In The Materials of Medieval Painting, (Daniel Thompson) explains that the darkening may be caused by the rearrangement of the internal structure of the red sulfide in mercury into the structure of black sulfide in mercury. Most methods of creating vermillion initially produce the black form of the mercuric sulfide, which is subsequently sublimed to form the red compound; reversion back to the earlier form of black mercuric sulfide is thus understood as a breaking down into the original compound. Exposure to light with wavelengths between 400 nm and 570 nm causes darkening, which can be reversed somewhat by placing the work in dark conditions. Despite the fact that some of the darkening can be reduced, once a passage of vermillion has turned color, there is no known way to completely change it back to its original red state. Of all the kinds of painting, wall paintings done in egg tempera seem to be the most susceptible to darkening.

Many scholars have hypothosized on the reasons for darkening. (Gettens & Stout) observe that wet process vermillion tends to darken more readily than dry process vermillion. Bomford theorizes that pressure and friction applied during the grinding process may also contribute to darkening. (Wehlte) believes that discoloration in oil painting is rarer than in pastel or water-based media, because in an oil vehicle the particles are completely surrounded by the binder and thus protected from contact with air and light. Although scientists are aware of what causes the darkening of vermillion, they have yet to discover exactly why this takes place; thus, despite years of study, a mystery continues to surround this pigment. One thing scientists have learned though is that the further the light can penetrate into the binding medium the more likely the vermillion is to darken. The use of red glazes, such as madder, cochineal lakes, and kermes, have proven to lessen the degree of darkening by preventing light from penetrating deep into the binding medium. Efforts to stop discoloration can be traced all the way back to Pompeii, where vermillion wall paintings were coated in wax. (Roy)

 

Binders

1998 Vermillion lab set-up

 

 

 

 

 

 

 

Using a medium weighing boat, 1.955 grams of powdered vermillion were combined with ten drops of linseed oil, which resulted in a thick, chunky paste. After adding two more drops to the sample, the mixture was spread evenly and thinly onto the provided glass sheet, producing a uniform bright red color. This medium remained wet and usable for several days following its production. According to (Max Doerner), vermillion retards the drying time of oil.

Next, again using a medium weighing boat, 1.099 grams of pigment were weighed out. The five drops of gum arabic added to the dry pigment were not absorbed immediately. Instead, the binder formed two beads, which were coated with the dry pigment. Interestingly, the pigment did not absorb into the binder for several minutes. Following its absorption, the resulting medium was a bright, homogeneous red thick paste that could be easily spread.

To use the egg tempera binder, 2.052 grams of dry pigment were measured into a large weighing boat. Next, two spatuals of egg emulsion were added to the dry pigment. That amount did not appear to be sufficient, so one more spatula of the emulsion was added to the sample. The sample became an orangey-red color, which was spread evenly onto the glass plate.

Typically, vermillion is stable and reacts well with other pigments. In the medieval period it was combined with lead white to create flesh tones in oil painting. Because of its elevated cost and tendency to darken over time, vermillion has historically been substituted and sophisticated by adding chrome orange, red lead, and other organic colorants. These combinations produced variants of vermillion. For example, "Carmine Vermillion" consists of red iron oxide and vermillion and "American Vermillion" are composed of chrome orange and a mixture of red leads and lakes. (Roy)

 

Vermillion in egg tempera

(objective: 20, lighting: 6, cross-polarized light, substage setting: 0.55, time: 2.5 seconds)

 

Optical characteristics: Looking through the microscope

Cinnabar and dry-process vermillion are similar in that their particles are irregular in size and have a fractured appearance when viewed under a microscope. Before grinding, cinnabar crystals are long and either deep crimson or violet-brown. The isotropic particles are translucent and deep red-orange when examined under transmitted light. Under reflected light, the same crystals take on a waxy appearance. After sublimation, dry process vermillion exhibits the radiating pencil-like structure of natural cinnabar. These two substances can be differentiated solely on the basis of impurities that can be detected through microscopic examination. Conversely, wet process vermillion particles are fine and uniform; individual particles tend to form aggregate crystals. (Roy)

During our microscope experiment, we discovered that the powder form of the pigment was characterized by fine, opaque particles with a homogenous appearance. They measured @25 µm in width. The regularity of these particles caused us to suppose that our sample was produced through the wet process (although, our pigment may be a modern chemical substitute for authentic vermillion). When combined with a linseed oil binder, the pigment appeared black when viewed using the 4x objective. Some areas of the sample were opaque, while others were translucent. Similarly, the combination of vermillion with gum arabic revealed a black color under the microscope. In the given sample, the pigment appeared primarily opaque, with the exception of one large translucent area. Next, powdered vermillion was combined with egg tempera. This binder produced a dark, reddish brown shade with a homogeneous appearance when viewed under a microscope using the 4x objective. Interestingly, when viewed under a stereomicroscope, the pigment had a solid, brilliant red hue in addition to a subtle gold sheen. The pigment had a homogeneous texture, and was uniformly opaque.

Health Issues

Specialists have determined that vermillion can cause skin irritation and allergies. Mercuric compunds are especially toxic to humans and can be inhaled or absorbed through the skin. Symptoms of mercury poisoning include psychic and emotional disturbances, followed by siezures, kidney disease, and nerve degeneration. Contact with mercury can also have a negative impact on reproductive capabilites.

Sulfides are very poisonous when ingested. They react with gastric acid and form hydrogen sulfide gas which can cause health problems. The danger of working with sulfides comes from the fact the sulfur oxides are emitted when a compound containing sulfur is heated or fired. Vermillion and other pigments containing mercury and/or sulfur are carefully labeled to alert artists of their toxic characteristics. (Rossol)

Links to other Web sites

For an interesting link about methods for pigments used in medieval icon painting, go to Ikons: Windows into Heaven (The Craft of Iconography) and visit Crafts, Pigments and Brushes

For information on the characteristics of mercury and the history of its usage, click this mercury website


 

Rachel Hildebrandt, Cindy Heller 1998.