Plaster

Clay Art Center in Tacoma stocks a selection of Plaster for the ceramic artist.

The most commonly used in the ceramics industry is Pottery Plaster No. 1, which offers an excellent balance of strength and porosity although it has lower green strength. It is ideal for press molds, slip casting molds, and damp boxes.

Hydrostone is much harder than Pottery Plaster and offers lower porosity. This is a highly durable choice for intricate molds, long lasting plaster bats wedging boards and reclaim slabs with slow and steady water absorption. Mixes with less water than other choices however it expands more during setting.

Hydrocal is sits in the middle of Pottery No. 1 and Hydrostone in terms of hardness and offers a bit more absorbency than Hydrostone. Good for case molds and hollow and thin walled molds with it’s lower viscosity, allowing it to flow into tight spots more easily.