Industrial Minerals
What it is
China clay, or kaolin, is a white aluminium silicate formed by the weathering of feldspar. It is prized for brightness, fine particle size and chemical inertness, which is why it ends up in everything from magazine paper to wall paint to sanitaryware.
Why buyers specify it
- High brightness at low cost, so it stretches titanium dioxide without greying the film.
- Plate-like particles improve opacity and hold a wet film in place on a vertical surface.
- Calcined grades add opacity and abrasion resistance where the raw clay is not enough.
- Low conductivity and stable chemistry make it safe in electrical and food-contact applications.
Grades we supply
Grade names are ours; the fineness and the duty are what you match against your current material.
| Grade | Type | Typical D50 | Usually bought for |
|---|---|---|---|
| XK-Coating | Water-washed | 0.7 – 2 µm | Paper coating, high-gloss paint |
| XK-Filler | Water-washed | 2 – 5 µm | Paper filler, emulsion paint |
| XK-Ceramic | Air-floated | 5 – 12 µm | Ceramic bodies, sanitaryware |
| XK-Calcined | Calcined | 1 – 3 µm | TiO₂ extension, cable compounds |
Other finenesses and surface treatments are available against a firm enquiry. If you are switching from another supplier, send their data sheet and we will match the curve rather than the mesh number.
Typical analysis
Chemistry
| Component | Typical range | Note |
|---|---|---|
| SiO2 | 45 – 49 % | — |
| Al2O3 | 34 – 38 % | Higher alumina means purer kaolinite |
| Fe2O3 | 0.4 – 1.2 % | The main brightness limiter |
| TiO2 | 0.2 – 1.5 % | — |
| K2O + Na2O | 0.2 – 2.0 % | Residual mica and feldspar |
| Loss on ignition | 11 – 14 % | — |
Physical properties
| Property | Typical range | Method basis |
|---|---|---|
| ISO brightness | 78 – 88 % | Elrepho |
| Oil absorption | 35 – 50 g/100 g | Spatula rub-out |
| Specific gravity | 2.58 – 2.63 | — |
| pH (10 % slurry) | 4.5 – 7.5 | Acid-washed grades sit low |
| Residue on 325 mesh | ≤ 0.1 % | Wet sieve |
| Moisture as packed | ≤ 1.0 % | 2 h at 105 °C |
These are typical ranges for china clay (kaolin), not a specification. The values that govern your order are the ones measured on your lot and printed on its mill test certificate. Ask for a sample and the certificate that goes with it before you commit a production trial.
Where it is used
China Clay (Kaolin) is not one product sold 5 ways — it is 5 different conversations about the same mineral. We supply it into paper & board, paint & coatings, ceramics & sanitaryware, rubber and adhesives & sealants, and in each of those the grade that works is chosen for a different reason: fineness in one, brightness in another, oil absorption or purity in the next.
Each industry below has its own page on this site, written for the people who formulate in it rather than for a general reader. If you work in one of them, start there — it will tell you which china clay (kaolin) grade we would quote for your application and what we need to know before quoting it.
- Paper & Board — Filler and coating pigment; the single largest use worldwide.
- Paint & Coatings — TiO₂ extender, flatting agent and film reinforcement.
- Ceramics & Sanitaryware — The white body former in porcelain, tableware and sanitaryware.
- Rubber — Semi-reinforcing filler, particularly in wire and cable compounds.
- Adhesives & Sealants — Volume and rheology in water-based adhesives.
Calcined or hydrous. Calcined kaolin is fired to roughly 1,000 °C, which drives off the structural water and raises brightness, opacity and hardness — and the price. If you are extending TiO₂, calcined usually pays for itself; if you are filling a paper furnish, hydrous is the economic answer. Tell us the job and we will quote both.
Packing
| Pack | Detail | Suits |
|---|---|---|
| 25 kg paper or PP bag | Palletised 40 bags per pallet, stretch-wrapped | Powders |
| 50 lb bag | US-standard weight where the plant prefers it | Powders |
| 1,000 kg / 1 MT jumbo bag | Four-loop FIBC with discharge spout | Powders, sand, granules |
| Bulk | Pneumatic tanker or loose in container, where volume justifies it | Sand, granules, lump |
Private-label bags with your own artwork are available from one container. How private label works.
Documents with every shipment
- Mill test certificate for the lot, with the measured values, not the range
- Certificate of analysis signed by the processing plant
- Safety data sheet in the US 16-section GHS format
- Certificate of origin and the commercial invoice and packing list
- Asbestos test report where the mineral and the application call for one
Need a price on china clay (kaolin)?
Send the grade, the tonnage and the delivery ZIP code. Quote and free sample back within one business day.