Making a Wedging Table
The table where clay is kneaded must be sturdy and may benefit from being screwed to the wall or to the floor. Other design considerations include: comfortable height (30 -32"), absorbent surface, cutting wire, and sufficient space to set scale.
Making our wedging table we build a wooden frame approx. 2" deep with a bottom made out of plywood. The plaster we used was Potter's plaster Number 1 that comes in 50 Lb. bags. A 50 Lb. bag fills up approx 1,150 cubic inches (for example; a frame 2' x 2' at 2" deep will add up to 1,156 cubic inches).
This plaster sets fast. Therefore, the mixing with water and the poring need to be done in the most time effective way to allow the plaster mix to settle level before it begun the harden. Even though the plaster will harden quickly, the plaster board need to dry for over a week before it can be used.
Pottery Plaster Mix For Wedging Tables:
For wedging boards or tables mix 70 parts of water to 100 parts plaster. This equals 4.17 gallons water per 50 pounds dry pottery plaster.
Successful mixing and use of industrial plasters requires following specific standards and procedures:
- The purest water available should be used; almost all drinkable water is suitable.
- A controlled temperature setting will provide the best results. Plaster and water should be contained at room temperature.
Room temperature is about 70 degrees.
- Since water-to-plaster ratios effect absorption, strength, and mold performance, they should be continually checked by
weighing the slurry in a container of known volume.
- If strength is the most important factor, longer mixing times are suggested, taking care not to over mix into the setting action
of the plaster, which decreases strength.
- Batch size should allow for the pouring to be completed within 5 minutes after the slurry has been mixed.
- Plaster should be sifted slowly and evenly into water. Do not drop handfuls of plaster directly into the water.
- Hand mixing is only acceptable for batches up to 5 pounds.