Drying Clay – Adelaide

Consider the Climate and Weather

• Summer (Hot & Dry): Adelaide summers are hot, often exceeding 30°C, with low humidity. In these conditions, clay can dry very quickly, which increases the risk of cracking or warping.
• Winter (Mild): Winters are milder, with temperatures ranging from 10-15°C, and slightly higher humidity levels. In this season, drying takes longer and can be more unpredictable, with clay potentially becoming too soft or developing mold.

Adjust Drying Conditions Based on Season

Summer (Hot & Dry)

• Avoid Direct Sunlight: In hot, dry conditions, avoid placing your piece in direct sunlight, as it can cause uneven drying, leading to cracks or warping. Instead, place your piece in a shaded, well-ventilated area.
• Cover with Plastic: Use plastic to cover the piece loosely, particularly in the first stage of drying. This slows down the evaporation rate, giving the clay a chance to dry evenly without rapid shrinkage.
• Check Often: Given the heat, the surface will dry faster than the interior. Regularly check the piece for any signs of cracks or dryness and adjust the drying speed as necessary by removing or adjusting the plastic cover.
• Use Damp Boxes: To slow down the drying process, consider using damp boxes (boxes with damp towels or cloths) to keep the humidity level stable and prevent the clay from drying out too quickly.

Winter (Mild & Cool)

• Control the Drying Rate: In winter, the cool temperatures and slightly higher humidity levels can cause clay to dry too slowly, increasing the risk of mold growth and uneven drying. Try to create a slightly warmer, controlled environment by covering your piece with plastic and placing it in an area with moderate air circulation (but not direct heat).
• Damp Boxes for Winter: You can also use damp boxes or place the piece near a gentle heat source, such as a radiator or ceramic heater, to ensure even drying without rapid moisture loss. Just be cautious of overheating or causing uneven drying.
• Avoid Too Much Moisture: Excess moisture in the air can cause the clay to remain too wet and slow down drying. Ensure that the drying space is not overly humid, as this could affect the piece’s final result.

Initial Drying in Warm Conditions

• Surface Drying: After shaping your flat piece, let it dry for a few hours in a shaded area with good airflow. In hot weather, this will help the surface set. During this stage, check the piece every few hours for any signs of cracking. If cracks appear, lightly mist the area with water to help it rehydrate and rework the clay.
• Turn and Rotate: As always, rotate the piece every 12 hours or so to ensure even drying on all sides, preventing warping and cracks.

Plastic Covering (in Both Seasons)

• Summer when it’s hot and dry, cover the piece with plastic for the first 12-24 hours of drying to slow down moisture evaporation.
• In winter, plastic will help prevent the piece from becoming too damp, especially in a cooler, humid environment. However, in winter, make sure the piece isn’t too sealed in plastic, as it can retain excess moisture and prolong drying.

Leather-Hard Stage and Further Drying

• Summer: After the first day or so, your piece will reach the leather-hard stage more quickly in summer due to faster moisture loss. At this stage, it can be handled and refined. If you notice that it is drying too quickly or unevenly, mist lightly with water and cover it again with plastic to slow down the drying process.
• Winter: In winter, it may take longer to reach the leather-hard stage, so ensure you check it frequently. Use a damp sponge or soft cloth to smooth rough areas, but avoid excessive moisture that might cause the clay to soften too much.

Final Drying to Bone Dry

• Summer: During summer, the piece will likely dry faster, so after it reaches leather-hard, give it about 2-3 days of drying time in the shade. Ensure it is completely dry and light to the touch before moving to the kiln. If you tap it gently, it should sound hollow and feel bone dry.
• Winter: In winter, give it a few extra days, as the drying process is slower. If you’re using plastic or damp boxes, be patient and let the clay dry fully. Bone-dry clay should be light, firm, and dry to the touch with no coolness when pressed.

Consider the Kiln Firing Process

• Summer Firing: When firing in the summer, ensure that your kiln area is well-ventilated and that the piece is bone dry before loading it into the kiln. In hot weather, kiln firing times might also be quicker, so ensure you monitor the firing schedule to avoid any issues.
• Winter Firing: In winter, ensure the kiln is set to the proper temperature and firing schedule. The cool, damp weather might affect your kiln’s efficiency, so consider preheating the kiln slightly if necessary.

Extra Tips for Both Seasons

• Humidity Levels: Adelaide’s humidity levels can vary greatly, so if you’re unsure, always feel the piece at different stages of drying. Humid conditions slow the drying process, while dry conditions speed it up. Use your judgment to decide if the piece needs a bit more drying time.
• Pre-Firing: Before placing the piece in the kiln, ensure it’s completely dry. A gentle tap with a tool should produce a hollow sound, and a needle tool test should show no moisture. If you’re unsure, leave it to dry for an extra day.

Quick Summary for Adelaide’s Climate:

• Summer: Protect your piece from direct sunlight, cover loosely with plastic to slow drying, rotate frequently, and check for cracks. Drying will be faster, so take extra care with handling and checking moisture levels.
• Winter: In cooler, more humid weather, slow down the drying process by using damp boxes or indirect heating, and be patient as drying will take longer. Monitor the piece for mold and excessive moisture retention.