cosmetic

Purity and composition

●     Iron oxide content ≥95% (Superior grade requires ≥96%, refer to GB/T 1863-2008)

●     Heavy metal limits

●     Lead (Pb) ≤ 10 mg/kg

●     Arsenic (As) ≤ 3 mg/kg

●     Mercury (Hg) ≤ 1 mg/kg

●     Cadmium (Cd) ≤ 5 mg/kg

Particle size control (directly affects skin feel)

●     Common iron oxide: 0.1–0.7 micrometers (suitable for pressed powder and eyeshadow)

●     Micronized  transparent iron oxide (for high-end liquid foundations)

●     Dv(90) ≤ 40 nm ( 90% of the particles are smaller than 40 nanometers)

●     D50 ≤ 300 nm (median particle size, which determines whether it feels "powder-free")

Dispersibility and stability

●     Tinting Strength : 97–103% (based on the standard sample being 100%)

●     Residue on sieve (325 mesh) ≤ 0.05% → Avoids grittiness and pilling.

●     Lightfastness: Level 6–7 (almost no fading)

●     Heat resistance

●     Iron oxide yellow: ≥160℃ (Overheating will cause it to turn red)

●     Iron oxide red ≥400℃

●     Iron oxide black ≥300℃

pH value and chemical stability

●     Aqueous extract pH = 3.0–7.0 (close to the slightly acidic environment of the skin)