China Kaolin Clay Wholesale
China Kaolin Clay Wholesale – Technical Overview
Kaolin clay, also known as china clay, is a naturally occurring hydrous aluminum silicate formed by the weathering of feldspar-rich rocks. Its primary mineral constituent is kaolinite, which provides a platy morphology that influences rheology and surface area.
The chemical makeup of typical wholesale grades consists of approximately 38‑46% aluminum oxide (Al₂O₃), 45‑50% silicon dioxide (SiO₂), and 0.5‑1.5% loss on ignition (LOI) at 1000 °C. Trace amounts of iron oxide, titanium dioxide, and potassium oxide may be present depending on the deposit.
Key physical properties that affect performance in industrial applications include brightness, particle size distribution, pH, and specific gravity. These characteristics are measured according to standardized test methods and can be adjusted through processing such as calcination or delamination.
| Property | Typical Value | Test Method |
|---|---|---|
| ISO Brightness (457 nm) | 85‑92% | TAPPI T 452 |
| Median Particle Size (d50) | 1.5‑2.5 µm | Laser Diffraction (ISO 13320) |
| pH (10% slurry) | 4.5‑5.5 | ISO 787-9 |
| Loss on Ignition (1000 °C) | 0.4‑0.8% | ASTM C 311 |
| Specific Gravity | 2.60‑2.65 g/cm³ | ASTM D 854 |
In the paper industry, kaolin serves as a filler and coating pigment where its high brightness and fine particle size improve opacity, gloss, and printability. The platy particles align during coating, creating a smooth surface that reduces ink absorption and enhances sharpness of halftone dots.
Ceramic manufacturers utilize kaolin for its low iron content and consistent sintering behavior, which contributes to vitreous bodies with minimal warping. The alumina‑silica ratio influences the firing range, allowing formulation of porcelain, sanitaryware, and tile bodies with targeted vitrification temperatures.
In polymer applications such as rubber and plastics, kaolin acts as a reinforcing filler that improves tensile strength, abrasion resistance, and dimensional stability. Its surface chemistry can be modified with silanes to enhance compatibility with hydrophobic matrices.
Quality control for wholesale shipments includes lot sampling, chemical analysis, and physical testing according to ISO 9001‑aligned procedures. Each batch is accompanied by a certificate of analysis reporting brightness, particle size, LOI, and major oxide percentages.
Packaging options range from 25 kg multi‑wall paper bags with polyethylene liner for easy handling, to 1‑tonne flexible intermediate bulk containers (FIBCs) for high‑volume consumers. Bulk shipments are typically loaded in 20‑ft or 40‑ft containers with moisture‑absorbent desiccants to maintain product stability during transit.
Typical lead times for ex‑works delivery from Chinese ports range from 2‑4 weeks after order confirmation, depending on destination port customs clearance and vessel scheduling. Expedited air freight is available for urgent sample quantities.
Frequently Asked Questions
- Can the particle size distribution be adjusted for specific coating viscosities?
- What information is required to receive a formal quotation (quantity, grade, packaging, destination)?
- Which international standards (ISO, ASTM, EN) are referenced for your test reports?
- How is moisture content controlled during storage and transport to prevent clumping?
To discuss technical specifications, request samples, or arrange a quotation, please contact our sales team using the inquiry form below.
Send Inquiry