Mixing plaster perfectly every time!
My tips on mixing plaster perfectly, plus a link to the Glazy Plaster Calculator — your new best friend! The Plaster Calculator also includes easy instructions, using the volume of a solid, the Plaster Calculator allows you to estimate how much plaster and water is needed for your next project!
Plaster consistency is the water-to-plaster ratio expressed as parts water per 100 parts plaster. A consistency of 70 means that you will need 70 parts of water for 100 parts of plaster. Consistency affects the hardness of the plaster.
Higher consistencies have more water and are softer, lower consistencies have less water and are harder.
Each brand of plaster has a recommended usage and consistency, so make sure you read there instructions carefully. Common pottery plasters for slip and press casting molds, bats and wedging tables have medium consistencies of 67-70.
A few tips:
- For ceramics suggest using Potter Plaster instead of regular plaster that you might find a bunnings. Potters plaster is stringer and made for purpose.
- Always add the plaster powder to the water gradually, never the other way around, and mix gently to avoid lumps and incorporate air bubbles; use a paddle mixer for best results and ensure the consistency is smooth and creamy, similar to heavy cream.
- Add plaster to water: Sprinkle the plaster powder into the water slowly to avoid clumping.
- Mix gradually: Stir gently from side to side to combine the plaster and water evenly.
- Check consistency: Aim for a smooth, creamy texture, not too thick or watery.
- Use a paddle mixer or for larger batches, use an electric drill with a paddle attachment to mix thoroughly.
- Remove air bubbles: Tap the mixing container on a surface to release trapped air bubbles.
The online Glazy Plaster Calculator will be your new best friend! It may not have Australia plaster brands but I found the it still worked fine for me.
Potters Paster in Australia can be purchased your local Potter Shop, I use Gyprock Pottery Plaster from Walkers Ceramics. But it's widely available everywhere.
