How to Seal Raku Pottery

Sealing raku pottery is an essential step to preserve its unique and delicate finish. Raku pottery, known for its striking textures and crackled patterns, is created through a rapid cooling process that makes it more porous and susceptible to damage. Proper sealing not only enhances the longevity of the piece but also protects it from moisture and staining.

Whether you’re a seasoned ceramicist or a beginner, understanding how to effectively seal raku pottery is crucial to maintaining its beauty and integrity over time. In this article, how to seal raku pottery is discussed.

Why and When to Seal Raku Pottery?

Sealing raku pottery is essential for preserving its delicate beauty and functionality. Since raku pottery is inherently more porous due to its unique firing and cooling process, it is particularly vulnerable to moisture, stains, and cracks. Without proper sealing, raku pieces are at risk of absorbing liquids, which can lead to structural weakening or a compromised appearance over time.

The best time to seal raku pottery is after it has been thoroughly cleaned and dried, ensuring there is no dirt or residue that could interfere with the sealing process. For decorative pieces that will not encounter significant wear and tear, sealing may serve primarily to enhance and protect the finish. However, for functional items such as planters or vessels exposed to water or outdoor conditions, sealing becomes a vital step to prevent long-term damage. Understanding the purpose and exposure of your raku pottery will guide you on when sealing is necessary.

Materials You’ll Need

To properly seal your raku pottery, gathering the right materials is essential. Here’s a list of items you’ll need to get started:

Clear Sealant

The most important material you’ll need is a clear sealant specifically designed for pottery. This can be found at most craft stores or online retailers. It’s important to use a sealant that is meant for pottery, as other types may not adhere properly or could even damage the surface of your piece.

Paint Brush

A paintbrush will be used to apply the sealant onto your raku pottery. You can use any size or type of brush, but make sure it is clean and free of any previous paint residue.

Protective Gear

When working with sealants, it’s important to protect yourself from fumes and potential skin irritation. Make sure to wear gloves, safety glasses, and a mask to protect your hands, eyes, and respiratory system.

7 Simple Step-by-step Guidelines on How to Seal Raku Pottery

Step 1: Prepare Your Workspace 

Begin by setting up a clean and well-ventilated workspace. Ensure you have a stable surface to work on and cover it with a protective sheet or newspaper to catch any spills. Keep all your tools, including the paint brush, sealant, and protective gear, within easy reach.

Proper ventilation is crucial when working with sealants, so open windows or use a fan to maintain good airflow. This preparation ensures a safe and efficient sealing process.

Step 2: Prepare Your Pottery

Before applying the sealant, make sure your pottery is completely dry and free of any dust or debris. You can use a damp cloth to wipe away any dirt and let it dry for a few minutes before proceeding.

If you are working on previously glazed pottery, gently sand the surface with fine-grit sandpaper to create a rougher surface for better adhesion of the sealant.

Step 3: Choose Your Sealant

There are various types of sealants available in the market, such as acrylic, polyurethane, and wax-based sealers. Each has its own unique properties and finishes. Take some time to research and choose the right sealant for your project.

Consider factors such as durability, water resistance, and the type of finish you want. Keep in mind the intended use of your pottery – if it will be used for food or beverages, make sure to choose a non-toxic sealant.

Step 4: Application

Once you have chosen your sealant, it is time to apply it to your pottery. Make sure to read and follow the manufacturer’s instructions carefully. Some sealants may need to be mixed before application, while others can be applied directly from the container.

Using a clean brush or sponge, apply an even coat of sealant onto the surface of your pottery. Work in small sections at a time and make sure to cover all areas, including the inside and outside of your piece. Avoid applying too much sealant as it may result in drips or pooling.

After the first coat has been applied, allow it to dry completely before applying a second coat. This will help ensure that your pottery is fully sealed and protected. Once both coats have dried, gently sand down any rough spots or imperfections using fine-grit sandpaper. This will give your pottery a smooth finish and remove any excess sealant.

Step 5: Curing

Curing is an important step in the sealing process as it allows the sealant to bond fully with the surface of your pottery. It also helps to increase the durability and longevity of your piece. To cure your pottery, you will need to heat it in a kiln or oven.

If you have access to a kiln, follow the manufacturer’s instructions for curing pottery. Generally, this involves gradually increasing the temperature over several hours until it reaches a high temperature and then slowly decreasing the temperature over several more hours. This process can take anywhere from 8 to 12 hours, depending on the size of your pottery.

If you do not have access to a kiln, you can also cure your pottery in an oven. Preheat your oven to the lowest possible setting (usually around 200°F/90°C) and place your pottery inside for about 30 minutes. Then, gradually increase the temperature in increments of 200°F/90°C every 30 minutes until the desired curing temperature is achieved. Keep in mind that this method may not produce as strong or durable results compared to using a kiln.

Step 6: Finishing and Decorating

Once your pottery is fully cured, you can begin adding any finishing touches or decorations. This is where your creativity can really shine! You can use paint, glazes, decals, or even carving tools to add designs and patterns to your pottery.

If you are using paint or glazes, make sure to follow the instructions provided by the manufacturer for proper application and curing. If you are carving designs into your pottery, be sure to handle it with care as it can still be fragile at this stage.

Step 7: Final Touches

After decorating, it’s time for some final touches. Use sandpaper or a soft cloth to smooth out any rough edges or imperfections on your pottery. You can also add a layer of clear glaze for a glossy finish.

Next, check for any cracks or chips and use a small brush to fill them in with extra clay slip. Let it dry completely before moving on to the final step.

Following the instructions on how to seal raku pottery, carefully load your pottery onto a kiln shelf and fire it at the appropriate temperature and duration. Once it’s cooled down, you can remove it from the kiln and admire your finished piece.

Common Mistakes to Avoid

When working with raku pottery, several common mistakes can impact the final outcome. One frequent error is not allowing the pottery to dry thoroughly before firing, which can lead to cracks or even explosions in the kiln. It’s also important to avoid overloading the kiln, as overcrowding can disrupt airflow and result in uneven firing. Another mistake is neglecting to properly seal the pottery, which can affect its durability and ability to retain its finish.

Additionally, be cautious when handling the pottery post-firing, as improper cooling techniques or rushing the process can cause thermal shock and damage the piece. By staying mindful of these pitfalls, you can achieve a more successful and satisfying result in your raku pottery projects.

Frequently Asked Questions

Q1: What is the Best Type of Clay for Raku Pottery?

A: The most commonly used clay for raku pottery is a low-fire, porous clay with high sand content. This type of clay is essential for achieving the signature crackled and smoked effects in raku pottery. Other types of clay can also be used, such as stoneware or porcelain, but they may not produce the same results.

Q2: Can Raku Pottery Be Used for Functional Purposes?

A: While raku pottery is primarily considered decorative art, some pieces can also be functional with proper glazing and firing techniques. However, it’s important to note that rakuware is not food-safe due to its porous nature and should only be used as a display piece.

Q3: How Hot Does the Kiln Need to Be for Raku Firing?

A: Raku firing typically requires a kiln temperature of at least 1800°F (982°C) to allow the glazes to fully melt. However, temperatures can vary depending on the type of clay and glaze used. It’s important to carefully monitor the temperature during the firing process to achieve the desired results.

Conclusion

Raku pottery is a fascinating and dynamic ceramic art form that combines creativity, technique, and the unpredictable beauty of fire. While it requires careful attention to safety and detail, the unique textures and finishes produced through raku firing make it a rewarding process for artists and enthusiasts alike.

By understanding the materials, techniques, and firing conditions, creators can craft stunning pieces that reflect both tradition and their own artistic vision. Thanks for reading this article on how to seal raku pottery.