Chromite Powder /chromite flour for Glass Bottle Pigment
Chromite powder (South Africa Chromite Flour) is the most commonly used and cost-effective mineral colorant for producing green and amber glass bottles. It mainly relies on chromium trioxide (Cr₂O₃) for coloration.
I. Core Properties of Chromite Powder/chromite flour
- Main component: Cr₂O₃ ≥ 46%
- Common particle sizes for glass bottle production: 200 mesh, 325 mesh, 400 mesh (325 mesh is the most widely used, 0–45 μm)
- Maximum service temperature: Melting point approx. 2150℃, resistant to high-temperature glass melting at 1400–1600℃
- Stability: Chemically stable, lightfast, weather-resistant, and UV-resistant
- Cost advantage: More economical than synthetic chromium oxide pigments
II. Functions & Effects in Glass Bottles
- Primary coloration: Emerald green, olive green, Georgian green, dark green, etc.
- Auxiliary color matching: When combined with iron, manganese, etc., it can produce amber, brown glass bottles
- Functional benefits: Blocks ultraviolet rays and extends the shelf life of beer, red wine and other beverages
- Applications: Beer bottles, wine bottles, beverage bottles, food packaging bottles, decorative glass bottles
III. Application Guidelines
- Addition method: Added directly to the glass batch and mixed evenly before melting
- Dosage control: Generally 0.5%–3% (adjusted according to the desired color depth)
- Selection for green and amber glass ottles:
- 200/325 mesh: For general-purpose green bottles with high cost performance
- Above 400 mesh: Finer texture and more uniform color, suitable for high-quality bottles
Note: As a natural mineral, chromite powder may have slight color differences between batches, requiring stable raw materials and formulations.
IV. Comparison between Chromite Powder & Synthetic Chromium Oxide
| Item | Natural Chromite Powder | Synthetic Chromium Oxide (Cr₂O₃) |
|---|---|---|
| Cost | Low | High |
| Color Tone | Olive green, natural green | Pure, bright emerald green |
| High-Temperature Stability | Excellent | Excellent |
| Impurities | Contains small amounts of iron, magnesium, etc. | High purity |
| Applications | General-purpose green / amber bottles | High-end bottles requiring high color purity |
V. Selection & Purchasing Recommendations
- Prioritize South African chromite powder with Cr₂O₃ ≥ 46%, 325 mesh, and uniform particle size
- Require suppliers to provide chemical composition, particle size distribution, and fired color samples, and conduct small-scale tests to confirm performance
- Suitable for mass production of glass bottles with cost sensitivity and demand for natural green tones