How Long Does Clay Need To Air Dry?

Air dry clay is made from a synthetic, self-hardening modeling material that does not require firing in an oven. Unlike typical clays or ceramic materials that must be kiln-fired at high temperatures, air dry clay simply sets and hardens at room temperature. Air drying refers to the process that occurs once the molded clay has been exposed to air for a period of time. As the clay sits, the water slowly evaporates allowing the material to harden. Using air dry clay is an approachable and accessible alternative to traditional ceramic clays for modeling, sculpting, and crafting. It provides users a way to create durable, lightweight finished pieces without needing a kiln.

Define Air Dry Clay

Air dry clay is a modeling material made primarily from clay and water. Unlike other types of clay that require firing in a kiln to harden, air dry clay cures and hardens as it dries through evaporation.

The main ingredients in air dry clay are clay powders, such as porcelain or earthenware clays, and water. It does not contain any additional chemicals, polymers or firing agents. This allows the clay to dry naturally at room temperature without the need for baking.

Air dry clay is a versatile, easy to use material for arts and crafts. Its air-drying properties make it ideal for projects with children or beginner artists that do not require a kiln.

Drying Times

The amount of time it takes for clay to air dry depends on several factors, primarily the climate, thickness of the clay, and type of clay used. In general, thinner pieces made with polymer clay will dry the fastest, while thicker pieces made from natural clay will take much longer to fully dry.

For small, thin polymer clay pieces, drying can take as little as 24 hours if you live in a warm, dry climate. Larger pieces or those made in humid climates may take 48-72 hours. Natural clays like pottery clay can take anywhere from several days to a few weeks to fully air dry, again depending on climate, thickness, and drying technique.

As a general guideline, very thin clay items can dry in 1-3 days, small pieces in 3-7 days, and large, thick pieces in 1-4 weeks. However, testing the clay and knowing your climate is important to get an accurate drying time.

Factors Affecting Drying Time

There are a few key factors that impact how long it takes air dry clay to fully dry:

Humidity

Humidity levels play a big role in drying times. The higher the humidity, the longer air dry clay will take to dry. This is because moisture in the air slows down the evaporation of water from the clay. Dry environments with lower humidity will cause clay to dry faster.

Temperature

Warmer temperatures help clay to dry more quickly, while cooler temps will slow the drying process. Try to keep your air drying clay in a warm spot around 70-75°F for best results. Avoid excessively cool or drafty areas.

Clay Thickness

Thicker pieces of clay inherently take longer to fully dry than thinner pieces. This is because there is more material for the moisture to evaporate from. For fast drying, aim to keep clay projects thinner where possible.

Tips for Faster Drying

To decrease the drying time of air dry clay, there are a few tips you can follow:

Use a fan – Positioning a fan to blow air directly on your clay creation will significantly speed up the drying process. The constant airflow evaporates moisture from the surface. Just make sure the fan isn’t blowing so strongly that it disturbs delicate clay structures.

Use a dehumidifier – Dehumidifiers work by reducing the amount of moisture in the air. Placing your clay piece near a dehumidifier takes away some of the moisture, helping water evaporate from the clay. The lower humidity allows the clay to dry faster.

Work in thinner layers – Thick pieces of clay will take longer to fully dry than thinner layers. If possible, minimizing the thickness of your clay while still retaining the structure needed will cut down on drying time. The moisture has less distance to travel to reach the surface and evaporate away.

Stages of Drying

Air drying clay goes through several distinct stages as the moisture evaporates. Knowing the stages helps you identify where your project is in the drying process.

Wet

In the wet stage, the clay is still very moist and malleable. At this point, the clay can be formed into shapes and sculpted. It will feel cool and damp.

Leather-hard

As moisture starts evaporating from the outer surface, the clay will become leather-hard. The surface will feel dry, but the interior will still be somewhat moist. The clay holds its shape but is not completely dry.

Dry to the touch

In this stage, the entire clay feels dry on the surface but retains moisture inside. The clay will feel harder and less cool. At this point, clay can be handled without ruining the shape.

Fully cured

When clay is fully cured, all moisture has evaporated both on the surface and interior. The clay will feel hard, dry, and durable. Fully cured clay is ready for painting, varnishing, baking, or whatever final steps your project requires.

Testing Dryness

After your air dry clay has been drying for some time, how can you tell if it’s ready for the next stages? There are a few simple tests you can do to check the clay’s dryness:

Look – Air dry clay changes color as it dries. It will appear much lighter and paler when dry compared to its wet state. If your clay still looks dark and muddy, it needs more time.

Feel – Press your finger into the clay. Dry clay will be firm and should not indent. If the clay still feels cool, damp, or sticky, or if your finger leaves an impression, it is still too wet.

Touch test – Try touching the thickest parts of your clay piece with the back of your hand. Dry clay will feel close to room temperature. If it still feels cool or cold, that is moisture you are sensing and it requires longer drying.

Doing these simple dryness tests regularly will help you learn when your clay is ready for the next stages!

Curing

While the clay may feel dry to the touch after a day or two of drying, full curing takes much longer. Curing refers to the complete hardening of the clay throughout the entire sculpture or piece, not just on the outer surface.

During curing, moisture continues evaporating from the center and the clay particles bond together more permanently. Rushing this process can lead to cracks or weak spots where moisture becomes trapped. Allow several weeks for thorough curing before painting or sealing a clay artwork.

To help the curing process, avoid placing greenware in air-tight containers or plastic bags. Store pieces in open air instead, which enables continued evaporation. You can also periodically rotate or flip pieces while curing to promote even drying.

Testing if clay is fully cured involves looking for color changes throughout the thickness and feeling for any remaining cool or damp spots. When thoroughly cured, the clay will maintain its strength even if exposed to moisture.

Storing

After air dry clay has fully cured, it’s important to store it properly to prevent the clay from reabsorbing moisture from the air. The best way to store air dry clay is to seal it in an airtight container or bag. Plastic containers or zip lock bags work well for storage. You could also wrap the clay tightly in plastic wrap before putting it into the storage container. The key is minimizing air exposure.

Make sure to press out any air pockets from storage bags and squeeze excess air out before sealing. Air contains moisture that could re-wet the clay over time if left sealed in. It’s recommended to include a desiccant packet, like a silica gel packet, inside the storage container to absorb any residual moisture.

Store finished air dry clay pieces the same way, sealing them in airtight bags or containers to preserve the clay in its dried finished state. With proper storage, air dry clay can be kept for years without losing its workability or form.

Conclusion

Air drying clay is a fun and versatile modeling medium, but it requires more patience than other clays. Expect the drying process to take hours, days or even weeks, depending on the climate and thickness of the pieces. Resist the urge to rush air dry clay projects. Allowing clay ample drying time prevents cracking and structural problems. With the right storage methods, finished air dry clay pieces can last indefinitely.

Slow drying is a necessary step to create lasting air dry clay projects. Take the time to monitor drying and test pieces thoroughly before adding paint or sealants. Storing unfinished pieces in plastic prevents them from drying out too quickly. With care and patience, clay artists can enjoy creating detailed works that hold their shape for years to come.