Plaster Mold Mixing
The correct plaster-to-water ratio is critical for mold quality. Too much plaster makes a dense, hard mold with poor absorption. Too little plaster makes a weak, soft mold. Pottery Plaster #1 at the standard 73:100 ratio gives the best balance for slip casting.
Mixing Steps
- Always add plaster to water (never water to plaster)
- Sift plaster onto water surface over 2-3 minutes
- Let plaster slake (soak) for 1-2 minutes
- Mix gently by hand or with a mixer for 2-3 minutes
- Pour when mixture reaches cream-like consistency
- Vibrate or tap mold box to release air bubbles