How to Harden Sculpting Clay Without Molding

Hardened clay is suitable for wheel throwing or hand building.

Sculpting clay may be a water-based compound, polymer clay or air-dry clay. Water-based clay comes in liquid form, known as slip clay. The liquid clay can be transformed into a plastic clay suitable for sculpting by placing the clay on plaster moldings. The plaster moldings extract the moisture from the material and make it harder. If your clay is too liquid, you don't necessarily need plaster molds to harden your material. Clay hardens when it is in contact with air, but you need to carefully monitor your material because it may easily become unworkable.

Things You'll Need

• Yoghurt containers or bowls
• Wooden spatula or stick
• Linen pillow case

Instructions

1. Pour the liquid clay into yoghurt containers or bowls. If you have a large number of containers you can pour small amounts of clay in each, so your material will harden faster. Don't cover the containers, because clay needs air to harden.

2. Allow the clay to stay in the containers for 12 hours. The minerals in the clay sink to the bottom and some of the water will also evaporate.

3. Remove the water from the surface of the clay from each of your containers. Stir the clay with a wooden stick.

4. Place the clay in a linen pillow case for half a day. As an alternative, you may put the clay in a pair of jeans or any items made of linen, which absorb the water from the clay.

5. Check the consistency of the clay regularly until it is workable. If you are able to make a clay coil with a bit of clay and bend it without causing severe cracking, it is workable. The time required for the clay to harden depends on factors including the thickness of the clay and the humidity and temperature of the room.

6. Remove the clay from the pillow case when it is pliable. Wedge for up to 10 minutes and your material is ready.

Tips & Warnings

• Place the pillow case on the ground or outside in the sun to speed up the hardening time.

• If your clay becomes too hard and unworkable, place it in a bucket with an equal amount of water. Allow to sit overnight, remove the excess water and try again.

References

• South Newton School Corporation Home: Stages of Clay & Clay Preparation