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.

1. Basic Features

Chemical Composition:

Mixed type: FeOOH (yellow) + Fe₄[Fe(CN)₆]₃ (blue) → Green

Composite type: Fe₃O₄ (black) + Cr₂O₃ (chrome green) → Dark 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 and Alkali Resistance: Resistant to weak acids and alkalis; strong acids and alkalis may affect color.

Environmental Protection: Non-toxic (chrome-free), models containing some chrome green should pay attention to environmental protection standards.

Form: Fine powder, easily dispersible.

2. Preparation Method

(1) Physical Mixing Method

Mix and grind ferric oxide yellow and ferric oxide blue in proportion to achieve a green shade.

Advantages: Simple process, low cost.

Shortcomings: Temperature resistance limited by ferric oxide blue (<200°C).

(2) Chemical Co-precipitation Method

Through the coprecipitation of iron salts and chromium salts, calcining 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 turf, roof tiles.

Paints & Coatings:

Exterior wall coatings, industrial anti-corrosion 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).

Other:

Camouflage paints, 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 thermal resistance; suitable for coatings, plastics (low temperature)

Iron-chromium green ceramic coating (Fe₂O₃ + Cr₂O₃) - High-temperature and corrosion-resistant

Chrome-free Iron Green Fe₃O₄ + other stabilizers - Eco-friendly, but darker in color; for building materials, toys

Common International Models:

PG17 (Pigment Green 17, Chromium Iron Green)

Chrome-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 derivative

Color: Olive Green, Dark Green, Deep Green, Bright Teal Green

Temperature Resistance: 300~500°C, 1000°C+, 200~300°C

Lightfastness Excellent, Outstanding, Outstanding

Environmental friendliness, contains chrome, Chromium (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 applications.

More stable than organic green pigments (such as phthalocyanine green may decompose at high temperatures).

Some models can be free of heavy metals, complying with environmental regulations.

❌ Disadvantages:

The color is not as vibrant as phthalo green (suitable for matte, natural tones).

Chrome-containing models require attention to environmental compliance (e.g., EU REACH).

6. Important Notes

Temperature Limit: 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 thoroughly milled in paints and plastics to prevent agglomeration.

Environmental Compliance: Exported products must be tested for heavy metals (such as 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 a bright green, consider phthalocyanine green; for high-temperature resistance, choose chrome green or iron-chromium composite green. The specific choice depends on the application scenario (temperature resistance, environmental requirements)!