Main‑stream Mineral Colorant for Green Beverage Glass Bottles
Glass‑Grade Chromite Flour (Chromite Powder), 325 mesh, Cr₂O₃ ≥46%, South‑African origin
- Coloring mechanism: Trivalent chromium ions (Cr³⁺) provide green tone. Native iron inside ore assists toning to produce olive‑green, tea‑green and emerald‑green shades for soda‑lime‑silica beverage & beer bottles.
- Market advantage: Cost‑effective natural mineral colorant for mass‑production container glass. It cuts overall production cost by 35‑50 % versus synthetic chromium oxide green, ideal for large‑capacity glass furnaces.
- Popular particle size: 325 mesh (≤45 μm), ≥97 % passing sieve. Fine uniform powder minimizes black specks, stones and striae defects.
- Additional function: Resultant green glass blocks UV radiation, slows photo‑oxidation of beverage contents and extends shelf life.
- Process requirement: Maintain oxidizing atmosphere during melting. Reducing atmosphere converts Cr³⁺ to Cr²⁺ and causes blue‑grey color deviation.
- Impurity control: Strict limit on SiO₂, CaO, P and S to avoid bubbles and glass stones.
- Note: Synthetic chromium oxide green delivers brighter green color yet with much higher cost, mainly applied for high‑end special glass instead of mass‑produced beverage bottles.