Produced from low-impurity ferrophosphorus by ultrafine grinding and classification, with uniform fineness, good dispersion and minimal batch-to-batch colour difference. Its ultra-high tinting strength and stable colour development suit high-colour-appearance applications and diamond-tool matrices. P 22.0–26.0%, Si ≤3.0%, C ≤1.0%, S ≤0.5%, moisture ≤0.2%, oil absorption 12–20 g/100 g, commonly at 600, 800, 1000 and 1200 mesh with particle-size distribution adjusted to order. Packed in 25 kg laminated bags or paper drums, or 500 kg and 1000 kg bulk bags; store dry and sealed, and re-test if caking occurs.