Smalt Deep Coarse Pigment

Description

Smalt Deep Coarse (PB32) is a handmade single pigment smalt composed of potassium cobalt silicate glass ground to a coarse particle size. It produces a deep, historic blue with a cool, rich undertone and a strongly textured, granulating masstone. Compared to modern cobalt or phthalo blues, this pigment is lower in chroma and far more transparent, offering a softly weathered, Old Master blue rather than a high intensity modern color.

In use, Smalt Deep Coarse gives a subtle, atmospheric blue ideal for historical palettes, skies, distant architecture, drapery, and veiled glazes in landscape and figurative work. It has low tinting strength and a transparent to semi-opaque character, making it easily overpowered in mixtures but exceptional when used generously in washes or layered over more opaque undercolors. The "Deep Coarse" grind produces darker, more dramatic texture than fine smalt, with pronounced granulation and a distinctive mineral scatter in wet in wet passages and on rough papers.

This cobalt glass pigment is chemically stable as a glass but historically known to be more reliable in fresco and water based media than in oil, where very long term discoloration can occur. In artist's colors it offers a uniquely historical, mineral blue that serves as a subtle mixer and a characteristic statement color for work inspired by Renaissance and Baroque techniques, or for painters who prize strong granulation and visible pigment texture.

History

Smalt is one of the earliest cobalt derived blues and was widely used in European painting from the 15th to the 18th centuries as an affordable substitute for natural ultramarine. It is made by melting silica (quartz), potash, and cobalt bearing ores into a deep blue glass, then quenching and grinding the frit into pigment. Historically, different grades were classified by particle size: coarse smalt was favored for the deepest, most intense blues and the strongest textural effects, while finer grades yielded paler, smoother color.

Painters of the Northern and Italian Renaissance, as well as Dutch and Flemish masters, frequently used smalt in skies, draperies, and glazes, often in combination with ultramarine. Over time, however, some smalt containing oil paintings were observed to fade or gray due to interactions between the potassium rich glass and the oil binder. With the 19th-century introduction of synthetic ultramarine and cobalt aluminate blues, smalt largely fell out of regular use and survived mainly in glassmaking, ceramics, and conservation work. Modern artist grade smalt, particularly in coarse, deeply granulating grades like Smalt Deep Coarse, revives this historic pigment for those seeking its unmistakable mineral texture and softly aged blue character.

Pigment Information

Pigment Type: Synthetic (Inorganic) potassium cobalt silicate glass (smalt)
Suitable Mediums: Watercolor, Gouache, Tempera, Acrylic, Lime / Fresco, Ceramic applications; historically more variable in Oil
Lightfastness: Good
Opacity: Transparent to semi-opaque
Other Names: Smalt Deep Fine, Smalt, Potassium Cobalt Silicate Blue
Color Index Code: PB32
Image: 'The Nativity' by Girolamo Romanino from the National Gallery

Health and Safety

• For art use only. Not for cosmetic, food or children's use.
• Keep out of reach of children and pets. Do not eat, drink or smoke while working.
• Avoid creating or breathing dust. Work in a ventilated area and wear a NIOSH approved dust respirator (P100 or better) when handling dry pigment.
• Wear gloves and eye protection. Wash hands and work surfaces after use, and never rinse pigment into drains.
• Do not spray apply, sand or burn.
• If swallowed or if you feel unwell, contact a poison control center (U.S. 1-800-222-1222) or a doctor.
• Safety Data Sheet available on request.

Caution: Contains cobalt. May cause an allergic skin reaction. May cause allergy or asthma symptoms if dust is inhaled. Avoid breathing dust and repeated skin contact. Do not rinse into drains.

Caution: Natural earths and minerals contain crystalline silica (quartz). Breathing the dust over long periods can cause serious lung disease (silicosis) and lung cancer. Always use a dust respirator with the dry pigment.

WARNING: This product can expose you to crystalline silica (airborne particles of respirable size), which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov.