Red chalk, or sanguine, is an iron oxide drawing material used since the Renaissance. Learn how Leonardo invented red-on-red, how Watteau mastered trois crayons, and why this warm medium dominated 18th-century drawing.
In May 2024, the Castello Sforzesco in Milan opened an exhibition titled "... per gitar diverse linee. Red Stone Drawings from Leonardo to the Academies." The show displayed 40 sanguine drawings and 10 engravings spanning four centuries, from Leonardo's Study for Head of Leda (c. 1505-1506) to 19th-century academic nudes. The exhibition traced the history of a single drawing material: a red stone composed of iron oxide and clay that Renaissance artists quarried, cut into sticks, and used to make some of the most luminous drawings in Western art. The Italians called it sanguigna, from the Latin for "blood." The French called it sanguine. We still use both names.
Red chalk, also called sanguine, is a natural drawing chalk made from iron oxide, primarily hematite, mixed with clay, silicates, and other minerals. It is one of the three traditional natural drawing chalks, alongside black chalk (carbon-bearing shale) and white chalk (calcite). Red chalk produces a range of warm tones, from bright orange-red to deep reddish brown, depending on the mineral composition of the source quarry. It was used extensively from the 15th through the 18th centuries and played a central role in Renaissance and Rococo drawing. For a broader treatment of chalk as a category, see our entry on chalk.
This entry covers what red chalk is, how it works, its history from Leonardo to the academic tradition, which artists are known for it, and the techniques that make it distinct from other drawing materials.
Red chalk is a natural mineral stone. The primary pigment is hematite, an iron oxide mineral (Fe2O3) that gives the chalk its characteristic red color. The stone also contains clay, silicates, and various trace minerals that affect the hue. Different quarries produced chalks of different colors, ranging from crimson to orangey red, and artists purchased specific hues from color merchants who sourced the material from mines across Europe.
The Metropolitan Museum of Art's guide to chalk describes red chalk as "an iron-oxide pigment that contains clay and other mineral compounds. It was highly regarded as a drawing material from the fifteenth through the eighteenth centuries, when it was attractive to draftsmen for the quality of its color and broad range of effects. Different trace elements in the mineral account for a variety of related colors that range from crimson to orangey red."
Red chalk is prepared for drawing by cutting the natural stone into sticks and sharpening it to a point. The Ars Pictoria guide to drawing with chalks describes the process: the stone must be "neither soft nor hard, and not at all spongy, for it breaks up into thin pieces." The oxidized and rough surfaces are removed, the stone is squared off and cleaned, then cut into small pieces and sharpened so they can be fitted into a brass chalk holder. Once the point is sharpened with a knife, the artist can draw, but with "a very light hand, for the point easily flakes and shatters."
Red chalk deposits pigment on paper through direct contact. The stone is soft enough to leave a mark with minimal pressure, and the pigment adheres to the paper fibers. The mark can be linear (using the sharpened point) or tonal (using the side of the stick or by smudging). Red chalk can be blended with a stump, finger, or cloth, and it can be ground and mixed with water or gum arabic to create red washes.
Red chalk has ancient origins. Pliny the Elder, in his Natural History, refers to a "blood-coloured" stone known as haematite, used by doctors to staunch bleeding. By the Renaissance, hematite had been synthesized into crayon form for drawing. The Art UK guide to sanguine notes that Michelangelo, Leonardo, and Raphael all used red chalk for anatomical studies, and the medium never lost its association with the human body: the warm red tones suited the depiction of flesh.
Leonardo da Vinci was the artist who popularized red chalk in Italy. The Ars Pictoria guide notes that while Leonardo was not the first artist to use chalks, he "extensively explored the possibilities of these new media in numerous drawings and played a pivotal role in spreading and popularizing chalk drawing medium on the Italian peninsula." Leonardo invented a technique called "red on red": drawing with red chalk on red-toned paper. By applying a red ground to the paper, Leonardo created a mid-tone surface that allowed him to work in both directions, adding darker red for shadows and lighter red or white for highlights. This technique produced drawings of extraordinary delicacy, with a restricted tonal range that Leonardo seems to have deliberately sought out, reminiscent of the limited tonal range of silverpoint.
The 2024 Castello Sforzesco exhibition explored Leonardo's "red on red" technique in detail, showing how he used sanguine on red-pink prepared paper for works like the Study for Head of Leda (c. 1505-1506). The exhibition catalog included contributions from researchers at the Institut National d'Histoire de l'Art in Paris, the University of Bari, and NIKI in Florence, who studied the use of red stone in art workshops and the graphic techniques of the early 17th century in Milan. Read about the exhibition at Finestre sull'Arte.
Red chalk became more widely used from the mid-17th century onward, when advances in paper manufacture made the medium easier to handle. The Art UK guide explains: "developments in sizing, which affected how paper responded to inks and grease, and in the manufacture of paper, facilitating a much smoother surface, made this awkward medium easier to use." Peter Paul Rubens used red chalk for portrait drawings, including a spectacular drawing of his wife Helena Fourment that combined sanguine with black and white chalk in the trois crayons technique.
In the 18th century, red chalk dominated drawing. Jean-Antoine Watteau made hundreds of sanguine drawings, exploring the full tonal range of the medium. The Art UK guide describes Watteau as "the artist at the forefront of the exploration of sanguine," noting that his drawings "testify to drawing's increased popularity and academic status." Red chalk suited the 18th-century taste for spontaneity and visual effects. It made drawings appear more finished and more attractive to collectors, and its warm tones bridged the gap between graphic art and painting.
By the 19th century, natural red chalk had been largely replaced by fabricated alternatives. Mined supplies grew scarce, and manufactured sticks offered consistency. The academic tradition continued to use sanguine for figure drawing, and the medium remains a staple of art school education today.
Leonardo's The Drapery of a Chest and Sleeve (c. 1504-1508, Royal Collection Trust) uses red chalk with touches of black and white chalk on orange-red prepared paper. The Study for Head of Leda (c. 1505-1506, Castello Sforzesco) is a red-on-red drawing that demonstrates Leonardo's technique of applying red chalk to red-toned paper. Leonardo's anatomical studies also use red chalk, exploiting the medium's warm tones for the depiction of flesh and muscle.
Michelangelo used red chalk for anatomical studies, particularly of the male nude. The Art UK guide notes that Michelangelo, Leonardo, and Raphael all used sanguine for anatomical studies, drawn to the medium's association with the human body. Michelangelo's red chalk drawings combine precise hatching with broad tonal modeling.
Raphael used red chalk for figure studies throughout his career. A 2025 study published in npj Heritage Science used microscopy, multiband imaging, X-ray fluorescence mapping, and Raman spectroscopy to analyze Raphael drawings, revealing complex combinations of red chalk with metalpoint and iron gall ink on single sheets. The study found that Raphael used lead metalpoint for initial sketching, then reinforced outlines and shadows with ink, with red chalk applied for tonal depth. Read the study at Nature.
Rubens used red chalk for portrait drawings, most famously his drawing of his 16-year-old wife Helena Fourment. The Art UK guide describes this drawing as one that "encapsulates the union of drawing and painting, combining the intimacy of the private study with the artistic ambition of the painted portrait." Rubens focused the sanguine in the areas of the face, hands, and flesh, giving an earthly, fleshy quality to the portrait.
Watteau made hundreds of sanguine drawings over his short career. His early study Satyr pouring wine uses the trois crayons technique, focusing the sanguine in the areas of the face, hands, and nipples. A head of a white boy in profile in the Ashmolean Museum demonstrates Watteau's mastery of the medium, using "an astonishing range of red chalk marks" in conjunction with black chalk and delicate white highlights. After his death, many of Watteau's drawings were published as Figures de differents caracteres (c. 1726-1728), testifying to the elevated status of drawing in the 18th century.
Red chalk is applied through hatching (parallel lines for tone), cross-hatching (overlapping line sets for darker values), stumping (smudging with a stump or finger for diffuse tonal areas), and washing (ground chalk mixed with water or gum arabic, applied with a brush). The trois crayons technique combines red chalk with black chalk for shadows and white chalk for highlights on toned paper.
Leonardo's "red on red" technique involves preparing the paper with a red or orange-red ground, then drawing with red chalk on top. The ground provides a mid-tone, so the artist adds darker reds for shadows and lighter applications or white chalk for highlights. This produces drawings with a narrow, warm tonal range and a dreamlike delicacy.
Red chalk is greasy and difficult to erase. The Art UK guide notes that "sanguine crayons were greasy and difficult to erase," which is why red chalk drawings only became widespread with advances in paper manufacture that produced smoother surfaces. Once chalk is embedded between the fibers of paper, the fine particles are difficult to remove. Artists in the 18th century used breadcrumbs or pumice to scrape off unwanted chalk. A technique called "counterproofing" involved blotting a red chalk drawing with another sheet of paper, which fixed the greasy chalk and created a mirror-image reproduction that could be used for teaching and wider circulation.
Red chalk drawings require fixative to prevent smudging. The Ars Pictoria guide notes that 16th-century artists used natural resins like dammar to safeguard drawings executed with powdery media including chalk and pastel.
Red chalk is one of the three natural drawing chalks. Black chalk and white chalk are the other two, and the trois crayons technique combines all three. Pastel is the fabricated descendant of natural chalk, using the same iron oxide pigments but with controlled binder ratios. Conte crayons include a red sanguine version that replicates natural red chalk in manufactured form. Charcoal is a carbon-based medium that shares red chalk's powdery, blendable quality but produces black rather than red marks.
For more on drawing techniques, read our entries on cross hatching, tonal drawing, and chiaroscuro, or explore our post on how to read a painting.
The Royal Collection Trust at Windsor Castle holds Leonardo's red chalk drawings, including the drapery studies and anatomical drawings. The Castello Sforzesco in Milan holds the Study for Head of Leda and other Italian sanguine drawings. The Louvre holds Rubens's trois crayons drawings and Watteau's sanguine studies. The Ashmolean Museum in Oxford holds Watteau drawings. The Metropolitan Museum of Art has a collection of Renaissance and 18th-century red chalk drawings. These works are light-sensitive and displayed in rotation.
Red chalk is the drawing material that most closely resembles human flesh. Leonardo understood this and used it for anatomical studies. Watteau understood this and used it for portraits of young people. The warm, iron-oxide tones of sanguine connect the drawing to the body in a way that no other dry medium can. For more on the materials that work alongside red chalk, read our entries on chalk and pastel, or explore our guide to Leonardo as painter and scientist.
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