Sodium silicate is the common name for a compound sodium metasilicate, Na2SiO3, and is also referred to as liquid glass. It is composed of sodium oxide and silica, and the ratio of these compounds in aqueous solution influences its fluidity. Sodium silicate is commonly used in ceramics as a deflocculant in slip preparation by neutralizing the charges of particles in the slip, allowing for more even suspension and thinning. This is a pure sodium silicate solution and should be mixed with water to a 50/50 solution for most casting bodies.
In ceramics, sodium silicate can also be used in surface decoration to create a crackled surface texture on pots. Just follow these simple steps: 1. Brush the sodium silicate onto your cylindrical pot while it's still on the wheel. 2. Use a heat gun to dry the outer layer of sodium silicate. 3. Apply a layer of slip or underglaze overtop of the sodium silicate. 4. Use a heat gun to dry the layer of slip/underglaze. 5. Draw or carve through the slip/underglaze layer to expose the clay, or you can leave the slip as is. 6. The final step is what creates the crackle: place your hand back inside the pot and apply from the inside to open the vessel wider. The enlarging of the pot creates the crackling effect from the dried sodium silicate. 7. Fire and glaze as normal.