Iron Oxide Green
Iron Oxide Green
Iron oxide green is a composite inorganic pigment, commonly made by mixing iron oxide yellow (FeOOH) with iron oxide blue (Fe₄[Fe(CN)₆]₃), or by blending iron oxide black (Fe₃O₄) with chrome oxide green (Cr₂O₃). It boasts good weather resistance, chemical resistance, and environmental friendliness, making it suitable for construction materials, coatings, plastics, and other fields.
Basic Features
Chemical Composition:
Hybrid type: FeOOH (yellow) + Fe₄[Fe(CN)₆]₃ (blue) → Green
Composite: Fe₃O₄ (black) + Cr₂O₃ (chrome green) → Deep green
Color:
Light green (with a yellow tint), medium green, dark green (with a blue or black tint).
Stability:
Lightfastness: Excellent (superior to organic green pigments).
Thermal resistance: Generally withstands temperatures of 300~500°C (depending on the formula).
Acid & Alkali Resistance: Resistant to mild acids and alkalis; strong acids and alkalis may affect color.
Environmental Protection: Non-toxic (chrome-free), please note environmental standards for models containing a certain amount of chrome green.
Form: Fine powder, easily dispersible.
2. Preparation Method
Physical mixing method
Mix and grind iron oxide yellow and iron oxide blue in proportion to achieve a greenish hue.
Advantages: Simple process, low cost.
Disadvantages: Temperature resistance limited by ferric oxide blue (<200°C).
(2) Chemical Co-precipitation Method
Through the co-precipitation of iron salts and chromium salts, calcination forms iron-chromium green (Fe-Cr-O).
Advantages: Higher temperature resistance (up to 500°C), better stability.
(3) Coating Modification Method
Coating the iron oxide particles with oxides such as silicon and aluminum to enhance weather resistance and dispersibility.
3. Main Applications
Building Materials:
Color cement, tiles, artificial grass, roof tiles.
Paints & Coatings:
Exterior building coatings, industrial protective paints (high weather resistance).
Plastic & Rubber:
Suitable for PVC, PE, and rubber products (such as toys, pipes).
Ceramics & Glass:
Glaze, colored glass (high-temperature resistant models required).
Others:
Camouflage paint, art pigments, cosmetics (high purity).
4. Categories & Models
Type, Component, Features, Application Fields
Iron yellow + iron blue blend (FeOOH + Fe₄[Fe(CN)₆]₃) offers low cost but poor temperature resistance; suitable for coatings, plastics (low temperature)
Iron-chromium green (Fe₂O₃ + Cr₂O₃) high-temperature and corrosion-resistant ceramic paint
Chromium-Free Iron Green Fe₃O₄ + other stabilizers - environmentally friendly, but darker in color; suitable for building materials, toys
Common International Models:
PG17 (Pigment Green 17, Chromium Ferric Green)
Lead-Free Green (Eco-friendly, compliant with RoHS/REACH)
5. Comparison with Other Green Pigments
Green Iron Oxide (Cr₂O₃), Phthalocyanine Green (PG7)
Chemical Composition: Fe-Cr-O / Fe-based Cr₂O₃ copper phthalocyanine derivatives
Color Olive Green, Dark Green, Deep Green, Bright Teal Green
Thermal Resistance: 300~500°C, 1000°C+, 200~300°C
Lightfastness Excellent, Outstanding, Outstanding
Environmental Protection: Partially Chromium-Containing; Chromium-Containing (Hexavalent Chromium Risk); Non-Toxic
Cost: Mid-Low, Mid, Mid-High
Advantages and Disadvantages of Iron Oxide Green:
✅ Advantages:
Highly weather-resistant, suitable for outdoor use.
More stable than organic green pigments (such as phthalocyanine green may decompose at high temperatures).
Some models are available without heavy metals, complying with environmental regulations.
❌ Drawback:
The color is not as vibrant as phthalo green (suitable for matte, natural tones).
Be mindful of environmental compliance for chrome-containing models (such as EU REACH).
6. Important Notes
Temperature Limit: The mixed type (Iron Yellow + Iron Blue) has poor heat resistance, avoid using in high-temperature plastics (such as PP, ABS injection molding).
Dispersibility: Must be well-grounded in paints and plastics to prevent agglomeration.
Environmental Compliance: Exported products must be tested for heavy metals (e.g., Cr⁶⁺, Pb, Cd).
Summary
Iron oxide green is a high-stability, excellent weather-resistant inorganic green pigment, suitable for the building materials, coatings, and plastics industries. For vibrant green shades, consider phthalocyanine green; for high-temperature resistance, opt for chrome green or iron-chromium composite green. The specific choice depends on the application scenario (temperature resistance, environmental requirements)!
