Realgar

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Description

Realgar is a brilliant orange-red mineral pigment composed of arsenic sulfide. Its hue ranges from fiery scarlet to deep orange, with a crystalline brilliance that sets it apart from earth reds and iron oxides. When finely ground, it yields an opaque pigment with strong covering power and glowing warmth.

Compared to vermilion or cinnabar, Realgar leans more orange and is somewhat softer in body, making it highly striking but chemically unstable when exposed to light over time.

History

Realgar has been known and used since antiquity in Egypt, Mesopotamia, China, and later throughout Europe. It was employed in manuscripts, wall paintings, and ritual objects as a source of luminous red-orange. In alchemy, it was associated with transformation and was considered one of the “arsenical sulfides” alongside orpiment.

Chinese painters used it for brilliant red passages in scrolls and decorations, while in Europe it appeared in medieval manuscripts and early Renaissance painting. However, its light sensitivity caused it to darken over time, sometimes turning into yellow orpiment (As₂S₃).

By the 18th century, Realgar had largely fallen out of use as safer, more stable reds (vermilion, later cadmium reds) became available. Today, it remains a pigment of historical and conservation interest rather than a practical artist’s material.

Health and Safety

Warnings:

CANCER AGENT.

INHALATION MAY PRODUCE CANCER.

EXPOSURE MAY CAUSE HARM TO THE PREGNANT PEOPLE OR DEVELOPING FETUS.

INHALATION MAY CAUSE LUNG DAMAGE.

CONTAINS LEAD.

Precautions:

Keep out of reach of children and pets.

Do not consume.

Not for cosmetic or food usage.

Do not spray apply.

For further health information contact a poison control center.

Use care when handling dry pigments and avoid dust formation.

Use particular caution with fibrous, fine, or toxic pigments.

Do not eat, drink, or smoke near dry pigments.

Avoid breathing in pigment dust and use a NIOSH-certified dust respirator with sufficient rating for dry pigment.

Wash hands immediately after use or handling.

If dust is likely, always wear protective clothing to keep out of eyes, lungs, off skin, and out of any contact as well as keep area ventilated.

This product may contain chemicals known by the State of California to cause cancer, birth defects, or reproductive harm.

Warnings and bottle information are abbreviated.

Pigment Information

Pigment Type: Natural Mineral

Chemical Composition: As₄S₄ (Arsenic Sulfide, Tetraarsenic Tetrasulfide)

Suitable Mediums: Historically used in Fresco, Tempera, Manuscripts, Limited Oil Painting

Lightfastness: Poor (light-sensitive; degrades to pararealgar)

Opacity: Opaque

Other Names: Ruby Sulfur, Ruby of Arsenic, Sandarac, Red Arsenic

Color Index Code: Natural Inorganic (no CI designation; modern references sometimes list with arsenic sulfide pigments, related to PY39/PO)