Potassium hydroxide or sodium hydroxide. Caustic alkaline soluble that leaches out of wood ashes when they are soaked in water. Occasionally used as a flux additive in terra sigillata, as in the black slip on Classical Greek wares. Toxic in liquid state, and may cause burns.
Potassium hydroxide or sodium hydroxide. Caustic alkaline soluble that leaches out of wood ashes when they are soaked in water. Occasionally used as a flux additive in terra sigillata, as in the black slip on Classical Greek wares. Toxic in liquid state, and may cause burns.
Source: Clay: A Studio Handbook