Description
Cobalt Turquoise, Pigment Green 50 (PG50), is a cobalt titanate green spinel pigment. It is a turquoise-blue powder produced by high-temperature calcination, forming a stable crystalline spinel structure.
This pigment exhibits fair opacity in both ultraviolet and visible light and is chemically inert, heat-resistant, and stable under ultraviolet light. It is non-bleeding and non-migratory, with good durability. It is typically used in applications requiring resistance to heat, light, and weathering. PG50 is compatible with most resin systems and polymers and is non-warping.
| Pigment Names | |||||||
| Common Names (pigment): | English: cobalt titanate green spinel Chinese (Simplified): 钛酸钴绿色尖晶石 French: spinelle verte de titanate de cobalt German: kobalt-titanat-grüner Spinell Italian: spinello verde di titanato di cobalto Russian: зелёная шпинель титаната кобальта Spanish: espinela verde de titanato de cobalto |
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| Nomenclature: |
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| Pigment Information | |
| Color: | Blue Green |
| Pigment Classification: | Synthetic Inorganic |
| Colour Index: | Pigment Green 50 (77343) |
| Chemical Name: | Cobalt titanate green spinel |
| Chemical Formula: | (Co,Ni)TiO₃ |
| CAS No.: | 8186-85-6 |
| Series No.: | 5 |
| ASTM Lightfastness | |
| Acrylic: | I |
| Oil: | I |
| Watercolor: | I |
| Physical Properties | |
| Mean Particle Size: | 2.5 µm |
| Residue 325 mesh (44 µm): | 0.01 wt% |
| Surface Area BET: | 2.8 m²/g |
| Specific Gravity: | 3.7 |
| Density: | 3.7 g/cm3 |
| Bulk Density: | 0.44 kg/L |
| Refractive Index: | 2.0–2.3 |
| Heat Stability: | 800 °C |
| pH: | 11.1 |
| Oil Absorption: | 17 grams oil / 100 grams pigment |
| Conductivity: | 1230 µS/cm |
| Moisture: | 0.2 wt% |
| HBU: | 31 °C |
| TSR: | 42% |
| Health and Safety | No acute or known chronic health hazards are associated with this product’s anticipated use (most chemicals are not thoroughly tested for chronic toxicity). Protect yourself against potentially unknown chronic hazards of this and other chemical products by keeping them out of your body. Do this by avoiding ingestion, excessive skin contact, and inhalation of spray mists, sanding dust, and vapors from heating. Conforms to ASTM D-4236. |
For a detailed explanation of the terms in the table above, please visit Composition and Permanence.
Durability Ratings
| Lightfastness: | 8 (1–8) |
| Weatherability: | 5 (1–5) |
| Acid Resistance: | 5 (1–5) |
| Alkali Resistance: | 5 (1–5) |
Optical Properties
Reflectance measurements show strong near-infrared reflectance (approximately 700–1300 nm) and moderate visible reflectance, which together produce its characteristic turquoise-blue color. This contributes to its use in cool pigment systems designed to reduce heat buildup.
Origin and History
Cobalt-containing spinel pigments have been known historically, but cobalt titanate pigments are modern engineered materials developed for industrial durability and stability rather than traditional artists’ use.
Source and Manufacture
Calcining mixtures of cobalt and titanium produces Cobalt Turquoise and, at high temperatures, often nickel oxides, forming a stable spinel structure. Adjustments in composition modify the hue toward greener or bluer turquoise tones.
Permanence and Compatibility
Cobalt Turquoise is chemically inert and insoluble, with excellent resistance to light, heat, and chemical exposure. It is compatible with oils, acrylics, alkyds, and polymer systems.
Water-Based Paint
In water-based systems, Cobalt Tourquoise shows moderate tinting strength and may exhibit slight granulation depending on dispersion.
Oil-Based Paint
In oil, PG50 produces a durable, stable film with moderate opacity and tinting strength.
Oil Absorption and Grinding
Oil absorption is approximately 17 kg per 100 kg pigment. The pigment disperses readily and does not require extensive grinding.
Toxicity and Regulatory Compliance
Cobalt Turquoise is considered low in toxicity in its insoluble form. Standard precautions should be taken when handling powders.
Regulatory Compliance:
- 21CFR 170.39 (FDA) – approved for food-contact polymers (≤2%)
- AP(89)1 (Europe)
- AS2070-1999 (Australia)
- BfR (Germany)
- CONEG (USA)
- EN71.3:2013 Category I & III
- EU Packaging 94/62/EC
- FPL Green 50 (France)
- GB9685:2016 (China)
- RoHS / ELV / WEEE (EU)
- TCLP (USA)
Ecology
Cobalt Turquoise is inert and insoluble in water, does not release significant amounts of heavy metals, and can be removed mechanically from waste streams.
Summary
Cobalt Turquoise is a cobalt titanate green spinel pigment valued for durability, chemical resistance, and thermal stability. Its turquoise hue and infrared reflectance make it suitable for both industrial and artistic applications requiring long-term performance.
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