Is Raku Pottery Waterproof: Sealing Raku Ceramics

Raku is a type of Japanese pottery that is known for its unique firing process and beautiful finishes. However, one question many people have, is raku pottery waterproof?

Raku pottery is Not waterproof. This is due to the fast raku firing process, which fires at a low temperature. As a result, the firing process of the clay body leaves the pottery porous and susceptible to water damage. 

While some glazes may claim they are water-resistant, the raku pottery will eventually break down, and the pottery will once again be vulnerable to water damage. So let’s take a closer look at why and how you can protect your Raku Pottery from water damage.  

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Why is Raku Pottery Not Waterproof?

Raku pottery is a form of ceramic that is not waterproof because of the firing methods; the clay bodies undergo physical and chemical changes. As a result, the pottery is porous and cannot hold water without leaking. First, let’s take a look at the glazes used. 

Is Raku Pottery Waterproof with Glaze

Many Raku Glazes can contain metal oxides such as chromium oxide, copper, zinc, and lead, giving the Raku pottery its unique look. Unfortunately, these metals are toxic if consumed, and toxins are known to leach out of the pottery, making it unsafe to place food or liquid on it.

Although Low-fire ceramic glazes and Crackle Glazes may state on the label that they are food-safe, these low-fire glazes will still not be waterproof after they are raku fired. So even if you seal your Raku pottery after firing, it may not withstand the everyday use of a functional object.

Additionally, the Raku pottery glaze can be fragile and chip and flake off easily. During the raku firing, the glaze may not bond completely to the clay body as it does during a regular kiln firing. This can also cause contamination of the liquid in the Raku vessel.

What Happens During the Raku Firing Process?

The raku process involves placing the Bone Dry clay in a kiln for a bisque fire. Ethier a Gas or Electric Kiln is recommended. 

Then glaze and fire the pots in a Gas or Raku Kiln using a fast low-temperature firing method, heating the pottery to around 1,800 degrees Fahrenheit (982°C).

Some potters will fire lower or higher for different effects, which is still a lower temperature. Firing to lower temperatures leaves the ceramic piece more fragile and porous.

The kiln is fired up fast, and the red hot pots are quickly removed from the kiln. This will cause thermal shock.

Then the pots are placed out in the air, in cold water, or in a reduction chamber with combustible material. These flammable materials create a chemical reaction with the smoke, glazes, oxides, and reduction atmosphere.

This means that the glaze is more likely to Craze or Crack, which can harbor bacteria and make it unsuitable for drinking or holding liquid. Sometimes this can cause the clay body to crack also. 

It’s important to note that even unglazed clay is not recommended to hold liquid. Unglazed Raku pottery is not waterproof, and liquids will seep through the clay, making it impossible to hold liquids. 

Despite its lack of waterproofing, raku pieces can still be used for decorative purposes. There are methods to seal the pottery and make it water-resistant. However, it is important to note that these methods may not make the pottery completely waterproof and should be used with caution.

For more detailed information on the whole process, check out, How To Make Raku Pottery: A Step-by-Step Beginner Guide.

How to Waterproof Raku Pottery

Ultimately, it is important to keep in mind that raku pottery is Not typically waterproof. While there are some methods you can try to make your pottery waterproof, it is unlikely that you will be able to make it completely waterproof for a long period of time. 

When sealing and waterproofing your raku pottery, choosing the right product is important. Here are some features to consider when selecting the best product for your needs: 

Sealing raku pottery is similar to sealing things like wood and cement. For example, when I apply sealants to my cement Japanese lanterns and cement animal figures, I must reapply the sealant every year. The same for sealing my wooden porch.   

When choosing a sealer for your Raku pottery, it’s important to consider the type of finish you want to achieve. For example, some sealers will create a glossy finish, while others will create a matte finish. 

Sealing Raku Pottery

You’ll want to ensure the sealer is compatible with the type of glaze used on your pottery. Look for a sealer that specifically states that it is waterproof and can withstand exposure to moisture.

After researching various sealers, we’ve identified some good products that can be used to seal Raku pottery. These sealers offer a range of finishes and are compatible with most Raku glazes, ensuring your pottery is protected and looks its best.

You want to ensure that the product you choose is safe for use on Raku pottery. For example, some sealers and sprays contain harsh chemicals that can damage the finish of your pottery or even make it unsafe to use for plants or flowers. 

Consider the application method of the sealer you choose. Some sealers may require multiple coats or a specific application technique, while others may be easier to apply. 

I put together a list of sealants for Raku pottery. These sealants will protect your pottery from damage and enhance its beauty and durability. Read on to find the perfect sealant for your Raku pottery.

However, it is important to note that not all ceramic sealers are created equal. Some may provide better water resistance than others. Still, it is unlikely that any will make your raku pottery completely waterproof for an extended period of time. 

Craft Resin Crystal Clear Epoxy to Waterproof Raku Ware

This Craft Resin Crystal Clear Epoxy kit provides a waterproof barrier to protect your pottery and can enhance the beauty of your pieces by giving them a crystal-clear finish. 

If you want to waterproof your Raku pottery, then the Craft Resin Crystal Clear Epoxy Kit is the way to go. It’s easy to use and will give you a crystal clear, glassy smooth finish that may last for years.

This craft resin comes with everything you need, including resin, a hardener, a reusable mixing stick, gloves, and a manual. The epoxy resin is certified food safe, non-toxic, and free of VOCs and solvent materials, making it harmless to you and the environment.

The curing time is 24 hours, which may be longer than some other epoxy resins on the market. The pumps that come with the kit are not great, but pouring the resin is just as fine.

The Craft Resin Crystal Clear Epoxy Kit is easy to use and has a beautiful finish. In addition, the advanced formula really does release air bubbles automatically, resulting in a smooth, bubble-free finish. 

Plus, the fact that it’s food safe and non-toxic makes it a great choice for anyone who wants to use it inside of the piece, like a ceramic vase or bowl. Because we all use different glazes, clays, and techniques, I recommend trying it on a test piece first to make sure it is compatible with your raku pots. 

Plaid Clay Pot Sealer

Plaid Clay Pot Sealer on Raku pottery prevents water from leaking out of pots. It can be used on terracotta pots, saucers, planters, and more. The sealer dries in 24 hours and provides a clear, protective coating that doesn’t detract from the beauty of the pottery.  

However, the product has a strong odor when applied, and the thin consistency may require several coats to reach the desired level of protection.

Additionally, it may not be suitable for use on all types of pottery, so be sure to test it on a small area before applying it to your entire piece.

Overall, I recommend Plaid Clay Pot Sealer for anyone looking for a reliable water sealant for their Raku pottery. It provides effective protection and is easy to apply with the aerosol spray can. Just be sure to use it in a well-ventilated area and allow plenty of time for the sealer to dry before using your pots.

Mod Podge Dishwasher Safe Water-based Sealer

I have found that Mod Podge Dishwasher Safe Water-based Sealer is an excellent choice for sealing Raku pottery. This sealer is specifically designed to withstand the dishwasher’s rigors, making it ideal for pots. Still, I would not recommend putting your Raku pottery in the dishwasher. 

The sealer goes on smoothly and dries clear. It is water-based and will leave a glossy finish on your pottery. 

One thing to keep in mind is that this sealer is not recommended for surfaces that will come into contact with food, so I would NOT drink from it. So, if you are sealing a mug or bowl, you will need to use a different sealer. They should also not be used to hold water, such as used for live flowers. 

Overall, I highly recommend Mod Podge Dishwasher Safe Water-based Sealer for sealing Raku pottery that will be used for functional purposes. It provides a durable, glossy finish to protect your pottery and enhance its beauty. 

Vallejo Gloss Varnish Polyurethane

I have found that Vallejo Gloss Varnish Polyurethane is an excellent water sealant for Raku pottery. This varnish is a polyurethane-based product that can be used for sealing and protecting a variety of surfaces, including ceramics. 

This varnish also dries to a crystal-clear, glossy finish on the Raku pottery. It also provides a durable, long-lasting seal that protects the pottery from water damage, scratches, and other types of wear and tear.

Applying the Gloss Varnish is easy. Simply brush a thin layer of the varnish onto the surface of the pottery, making sure to cover all areas evenly. If necessary, Let the varnish dry completely before applying a second coat. 

Another advantage of this varnish is that it can be thinned with water, which makes it easy to adjust the consistency for different applications. It is also easy to clean up with soap and water, which is a big plus for me.

I highly recommend Vallejo Gloss Varnish Polyurethane as a water sealant for Raku pottery. It provides a beautiful, long-lasting finish that protects the pottery from water damage and other types of wear and tear. 

How to Make Raku Pottery Water Resistant

If you are not looking for a water holding vessel, here are a few products you can try that will help to protect the surface from water damage, extend its lifespan, and make it easier to clean. 

Be aware that they may affect the appearance of the pottery, so test it on a small area first. 

Aleene’s Spray Gloss Finish

I have found that Aleene’s Spray Gloss Finish is a great option for sealing Raku pottery. This spray gloss finish provides a shiny, protective coating that helps to preserve the Raku pottery.

One of the things I like about this sealant is how easy it is to apply. The spray nozzle allows for an even, controlled application to achieve a smooth, glossy finish without any brush strokes or uneven spots. Plus, the spray dries quickly, so you can handle your pottery soon after applying the sealant.

Aleene’s Spray Gloss Finish is also durable and long-lasting. It provides a strong barrier against moisture, so you can be confident that your Raku pottery will be protected from water damage. Additionally, this sealant is non-yellowing, so your pottery will maintain its original appearance over time.

Overall, I recommend Aleene’s Spray Gloss Finish to anyone looking for a reliable and easy-to-use sealant for their Raku pottery. It provides a beautiful, long-lasting finish that will help to preserve the unique beauty of your pieces. 

This sealant is NOT recommended for drinking liquids and should not be used to hold water for live flowers. 

Thompson’s Water Seal

Thompson’s Water Seal is mainly used as a concrete sealant, making it a popular choice for making Raku pottery water-resistant. It is a clear, water-based sealer that can be applied to the surface of the pottery after it has been fired. The sealer helps to repel water and prevent it from seeping into the porous clay, which can cause cracking or other damage over time.

When applying Thompson’s Water Seal, it is important to follow the instructions carefully. The sealer should be applied in a thin, even layer if you use a brush or sprayer. It may take several coats to reach the desired level of water resistance. Once the sealer has been applied, it should be allowed to dry completely before the pottery is used or displayed.

It is important to note that Thompson’s Water Seal is not a permanent solution for making Raku pottery water-resistant. Over time, the sealer will wear off and need to be reapplied. Additionally, the sealer may not be effective in all situations, such as if the pottery is constantly exposed to water or other harsh elements.

HOPE’S 100% Pure Tung Oil Sealer

We highly recommend using HOPE’S 100% Pure Tung Oil as a sealer for your Raku pottery. Tung oil is made from tung tree seeds. It has been used for centuries as a wood sealer and protectant, and it also works on pottery.

Tung oil is a popular choice for this, as it hardens when applied and creates a protective surface. Apply the oil to the inside of the pot and let it dry completely before using the pot. Be aware that using a sealant on the inside of the pot will not make the raku ware waterproof. 

When applying HOPE’S Tung Oil Sealer, be sure to follow the instructions carefully. You will need to apply several coats. Allow each coat to dry completely before applying the next. Once the final coat is dry, your Raku pottery will be water-resistant and protected from the elements.

Keep in mind that Tung Oil is not a permanent solution and will need to be reapplied periodically to maintain its effectiveness. However, with proper care and maintenance, your Raku pottery can last for many years to come.

Other Tips for Making Raku Pottery More Water-Resistant

One way to make your raku pottery more water-resistant is to use a less porous glaze. To achieve a waterproof piece, some potters will fire their mid or high-fire clay body to the right temperature that vitrifies the pottery. With this process, our glaze will take a long, long time dry. It will be equivalent to reglazing your Pottery.  

In most cases, you cannot make your Raku ware completely waterproof. For example, Raku firing does not reach high enough temperatures to vitrify the clay, making it waterproof. Low-fire clay also is not waterproof.

Conclusion

In summary, while Raku pottery is a beautiful and unique art form, it’s not recommended for liquids due to the raku firing process, the potential for glaze toxins, and fragility. 

However, there are ways to make raku pottery water-resistant. For example, coating the pottery with various materials can make it temporarily waterproof. Still, the pottery will suffer from continual seepage and eventually disintegrate with time. You can also place a smaller glass jar inside the raku pot to protect it from any moisture. 

Suppose you’re looking for a pottery option that is safe for drinking. In that case, it’s best to choose a type of pottery that has been specifically designed for this purpose. Look for pottery that has been fired at a high enough temperature to fully vitrify the clay, making it non-porous and waterproof

FAQ:

Can You Eat Out of Raku?

If you are wondering whether you can eat out of raku pottery, the answer is not straightforward. While people have been drinking out of raku pottery for ages, mainly in a Japanese tea ceremony, the raku glaze tends to chip over time and can easily be swallowed, which can be unsafe. Therefore, it is not recommended that you use raku pottery for food.

However, raku pottery can remain a great decoration. You can use it to display flowers or other non-edible items. However, these pieces are not safe for food. 

For more detailed information, check out, Is Raku Pottery Food Safe: What You Need to Know

Is Raku Pottery Dishwasher Safe?

No Raku Pottery is not Dishwasher Safe. Raku pottery is porous, which means that water can seep into the clay and cause it to crack or break. Additionally, the glazes used on raku pottery are not designed to withstand the high temperatures and harsh detergents used in dishwashers. Therefore, I would not even recommend it after sealing your pot. 

If you want to clean your raku pottery, the best way to do it is by hand with mild dish soap. Gently wash the pottery with a cloth or soft sponge. Be careful not to scrub too hard or use any abrasive materials that could scratch or damage the surface. Rinse the pottery thoroughly with clean water, dry it with a soft towel, or let it air dry.

Tips for Maintaining Raku Pottery

To keep your raku pottery looking its best, there are a few things you can do to maintain it.

Avoid exposing your raku pottery to extreme temperatures, such as placing it in a hot oven or freezing temperatures. Don’t use abrasive cleaners or harsh chemicals on your raku pottery. Avoid stacking your raku pottery or placing heavy items on top of it, as this can cause it to crack or break.

Taking these simple steps, you can help ensure that your raku pottery remains beautiful and functional for years to come.