Iron Oxide Blue
Iron Oxide Blue
Iron oxide blue is an inorganic blue pigment, chemically composed ofPrussian BlueOrPigment Blue 27 (PB27)It features a vibrant blue hue, but due to its poor weather and temperature resistance, its application is somewhat limited, mainly used in paints, inks, plastics, and similar fields.
Basic Features
Chemical Formula：Fe₄[Fe(CN)₆]₃（。
ColorDark blue, with a hint of green or red, depending on the synthesis method.
Stability：
Good lightfastnessProlonged exposure to ultraviolet light may cause fading.
Poor thermal resistance(>200°C Decomposition).
Poor acid and alkali resistanceWhen exposed to strong acids (HCl, H₂SO₄), it decomposes; when exposed to alkalis (NaOH), it turns green.
Insoluble in waterMay degrade slowly in damp conditions.
ShapeFine powder, microcrystalline structure.
2. Preparation Method
Ferric Oxide Blue is commonly obtained byIron(II) salt reacts with iron (K₄[Fe(CN)₆])Preparation:
Steps：
Ferrous sulfate (FeSO₄) reacts with potassium hexacyanoferrate(II) (K₄[Fe(CN)₆]) under acidic conditions.
The sediment is washed, dried, and milled to obtain ferric oxide blue.
3. Main Applications
Paints & Inks：
Suitable for low-end paints and printing inks (such as packaging printing), but not suitable for outdoor long-term use.
Plastic & Rubber：
Suited for low-temperature plastic processing (such as PVC, EVA), avoid high-temperature injection molding.
Stationery & Art Supplies：
Watercolor and oil paints (Prussian blue being a traditional blue pigment).
Other Applications：
Some cosmetics (require high purity, low heavy metal versions).
4. Comparison with Indigo Blue and Phthalocyanine Blue
| Features | Iron Oxide Blue (PB27) | Indigo Blue (PB29) | Phthalocyanine Blue (PB15:3) |
|---|---|---|---|
| Chemical Composition | Fe₄[Fe(CN)₆]₃ | Na₆Al₆Si₆O₂₄S₄ | Copper Phthalocyanine (CuPc) |
| Color | Deep Blue (dark shade) | Bright Blue (with a purple tint) | Vivid blue (with a green tint) |
| Temperature resistance | <200°C | ~800°C | ~400°C |
| Lightfastness | Generally | Excellent | Superior |
| Acid and alkali resistance | Discrepancy | Alkali-resistant, acid-resistant | Acid and alkali resistant |
| Cost | Low | Please provide the Chinese content you would like translated into American English. | Medium to High |
Disadvantages of Ferric Oxide Blue：
Easily damaged by acids and alkalis, not suitable for industrial anti-corrosion coatings.
5. Important Notes
Avoid high temperaturesProcessing temperature should not exceed 200°C; otherwise, decomposition may occur.
Avoid strong acids/alkalisPrevent color change or deterioration.
StorageSealed to prevent moisture, avoid long-term exposure to sunlight.
Summary
Iron oxide blue is a low-cost blue pigment, but due to its limited stability, it is mainly used in low-end paints, inks, and art pigments. For blue pigments with higher weather resistance and temperature resistance, considerIndigo blueOrPhthalocyanine Blue。
