Nigra Black Stoneware

From the manufacturers website:

Black Stoneware Body with Black Grog. At 1050°C and above, it develops into a dark anthracite colour.

Application Temperature: 1000°C - 1240°C

Specifications:

• Grog / Graining: 20% / 0-0.2mm

• Drying Shrinkage: 6.8%

• Firing Shrinkage:

  • 1140°C: 4.7%

  • 1190°C: 7.0%

  • 1240°C: 8.2%

• Water Absorption:

  • 1140°C: 7.3%

  • 1190°C: 3.0%

  • 1240°C: 0.2%

• Sintering (Water Absorption ≤2%): 1210°C

• Thermal Expansion Coefficient (20-400°C): 68 × 10⁻⁷/K (Pre-firing: 1200°C)

Safety Concerns with Black Clays

Concerns about the safety of black clays, both in the studio and on functional ware, are valid. Historically, some black clays were colored with manganese oxide, a known toxin

NIGRA 2002 sold under the Primo-Pro label is manufactured by a reputable European supplier and widely sold throughout Europe. We have our supplier’s absolute assurance that this body (pigmented with manufactured stains) is safe to use.