OPK – Ogun Plastic Kaolin

OPK stands for Ogun Plastic Kaolin, a bright white kaolin clay mined from Ogun State in southwestern Nigeria. Ogun State sits on substantial kaolin deposits that have been studied and used in Nigerian ceramics production for decades, and OPK represents a locally sourced alternative to the American industry standard EPK (Edgar Plastic Kaolin).

OPK’s defining qualities match what potters expect from a premium plastic kaolin: a clean white fired color, high plasticity (which is unusual for kaolins and highly valued in throwing bodies), and consistent chemistry suitable for a wide range of applications.

Chemically, OPK is a hydrated aluminum silicate (Al2Si2O5(OH)4), the same basic formula as all kaolins worldwide. Its performance differences come from particle size distribution and natural purity. Nigerian kaolins from Ogun State are known for their whiteness and workability, qualities that make OPK suitable for porcelain, bone china, and bright white stoneware recipes.

In glazes, OPK serves two main roles: it contributes alumina (Al2O3) to stabilize the glaze and prevent it from running off vertical surfaces, and it keeps dry glaze materials suspended in water so they do not settle to the bottom of the bucket during application.

Supporting Nigerian-sourced raw materials is part of building a sustainable local ceramics ecosystem. Where imported kaolins carry heavy freight costs and currency volatility, OPK offers potters a dependable, locally mined alternative at reasonable prices.

Typical usage: 5 to 15 percent in most glaze recipes for suspension and alumina. 10 to 30 percent in porcelain and white stoneware bodies. Direct substitute in any recipe calling for EPK, Grolleg, or generic white kaolin.

Equivalent materials: EPK (American), Grolleg (English).