Is Pottery Food Safe Without Glaze?

Pottery has been used by humans for thousands of years. Archaeological evidence suggests humans were using ceramics for cooking and transporting water as long as 20,000 years ago! With such a rich history of use, Is Pottery Food Safe without Glaze to use, serve, and eat food off of today??

The quick answer is yes, Pottery can be Food Safe without Glaze and safely used for dinnerware when using Mid and High-fire clays such as Stoneware Clay or Porcelain and fired as recommended.
When fired at higher temperatures, pottery becomes vitrified (glass-like) and waterproof, making it safe to use without glaze. This means Unglazed pottery pieces may be safely used for drinking out of or serving food.

Follow along as I share some of the rules and techniques that I have learned to help ensure your Pottery is Food Safe Without Glaze.

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What Makes Pottery Food Safe?

The food and drug administration says that an item can be called food safe when it can come into direct contact with food without causing a safety hazard to anyone who then eats that food. It can apply to pots, mugs, plates, dishware, and more in pottery.

The type of glaze used matters. The glaze must indicate that it is food safe. The Type of Clay you use for unglazed pottery also matters. Some clays produce food-safe pottery while others don’t.

Is Low Fire Clay Food Safe?

Low-fire clay literally means pottery fired at a lower temperature. These clays take less time to produce and have porous surfaces. Low-fire pottery is also known as Earthenware and does not comply with FDA standards of food safe clays and should be glazed if the piece will be in contact with food.

That being said, not all earthenware clays must be completely glazed for them to be safe. For example, some popular artisanal mugs are glazed on the inside only. The outside is only partially glazed or not glazed at all for artistic effects. This is perfectly safe, as long as the part you are eating or drinking off of is glazed.

Low-fire glazes are not all the same either. For example, if you are glazing low temperature clay bodies, you will need to make sure the low fire glaze is food safe.      

Are All Mid and High Fire Clay Bodies Food Safe?

High-fire clays known as Stoneware, Porcelain, and Ball clays can vitrify because the high temperatures cause the particles to fuse more tightly together for a non-porous, finished product. Once these clay bodies are fired to high temperatures, they are now vitrified (glass-like) and do not have to be glazed. Porcelain is one of the most popular clays that are unglazed.

Many Electric Kilns will fire to Cone 10 – 2345℉ (1285℃). The temperature needed to vitrify these clays without glaze.

Mid-fire clays can vitrify. If you have a cone 6 clay, it will vitrify at cone 6 – 2232℉ (1222℃)

If Mid or High fire clays are not fired to high enough temperatures, ceramic glazes must be applied for food use.  If you like to keep the unglazed look, you can glaze just the inside of your pottery. 

These are just a few things to consider when Choosing your Pottery Clay.      

What Is the Difference Between Glazed vs. Unglazed Pottery?

The main difference between glazed and unglazed pottery is the look and texture of the piece.

Unglazed pottery has a rustic, earthy look to it and can have a rough texture. Some products, such as Terra Cotta pottery, are left unglazed so they can remain porous and absorb water over time. However, this is not a desirable trait in an item intended for contact with food. Food-safe unglazed pottery falls into the category of Stoneware, Porcelain, and Ball clays.

Glaze is added to pottery to add sheen and color and make it water-tight. Earthenware is frequently glazed before use, although stoneware porcelain and ball clay are also glazed. A glaze typically contains a glass component like silica, a stiffening agent like alumina, and additional “flux” ingredients. In addition, some of these glazes contain a small amount of lead that stabilizes the glaze. Ideally, the lead fuses to the clay as it is fired, preventing the metal from leaching.

The best glazes for kitchenware are food safe and contain safer chemicals containing sodium, calcium, or magnesium fluxes. Items glazed with non-food safe ingredients must be labeled with a permanent, fired decal that declares that it is not safe to be used with food. However, imported, antique, and some hand-made products do not have the decal.

Why Is Porosity In Clay Important?

Porosity refers to the ability to absorb liquids into a solid material, made possible by microscopic holes in a substance. This means that while they will hold water, they will still absorb some of it over time, expanding and shrinking as it dries.

Earthenware can absorb water and other liquids. Bacteria, mold, and fungus can also develop. The porous surface of earthenware makes it extremely difficult to get an item thoroughly clean. Though an item may look clean, it can contain dangerous toxins that will leach into whatever food or liquid is stored in it next.

The risk of bacteria development is why pottery intended for use in contact with food should be non-porous. That means unglazed pottery has to be a high fire Stoneware, Porcelain, or Ball clay. As previously mentioned, these are waterproof, as the clay particles have melted together and vitrified to form a non-porous, glass-like surface. These clays are also harder and more durable than earthenware ones. That is why Ball clays and Porcelain are used in making sinks and toilets.

Is Raku Pottery Food Safe?

Raku pottery can use a low, mid, or high-fire clay body with a good amount of grog to help withstand thermal shock. Raku uses a low-firing process that does not vitrify the clay. The clay is bisque-fired to cone 04, 05, or 06 and fired again in a Raku Kiln to a temperature of 1,800°F (982°C), making traditional raku ceramics Not Food Safe.

For more detailed information on the Raku process, check out my step-by-step article on How to Make Raku Pottery.

Is Burnished Pottery Food Safe?

Burnished pottery is an alternative to glazing. The clay has been polished to create a smooth, shiny surface. It is often used to create a more decorative finish on pottery.

Burnished pottery is Not food safe unless the clay can be fired to vitrify. Mid fire cone 6 – 2232℉ (1222℃) or High fire Cone 10 2345℉ (1285℃) or higher. The resulting pottery will be vitrified and non-porous. This means that it will be completely waterproof and can be used for food and drink without worry.

However, suppose the pottery is not fired to this high temperature. In that case, it will remain porous and should not be used for anything other than decoration. So, if you’re thinking of giving your beloved a set of hand-burnished mugs, make sure they’re properly fired or glazed on the inside first.

How Do You Know if Pottery Is Food Safe?

Food safety is important for ceramic manufacturers of pottery dishware. To make unglazed food safe dinnerware pottery, the clay must be fired to a hot enough temperature to vitrify or use a food-safe glaze.  

If a pottery piece is especially old or looks to be chipped or damaged in some way, it is no longer considered food safe.

The potential danger of pottery comes from leaching toxic substances into food. For example, some earthenware glazes use toxic metals from organic materials. Natural materials can pose health hazards like lead poisoning. In addition, some clays can contain toxic metals. These harmful chemicals can leach into food if the pottery is not high-fired or glazed. In decorative pieces, this will not cause any problems to a person’s health, but it can be in an item like a coffee mug.

How Do I Make Sure Pottery Is Food Safe?

There are At-Home Tests that can be used to determine if any lead is lurking beneath the surface. It is recommended that you test all antique ceramics before using them in the kitchen because they may contain lead.

For potters who make functional ware, leach testing is an important way to ensure that their glazes are food safe. To leach test a glaze, simply squeeze a lemon wedge or lemon juice onto a glazed surface. You can also use orange Juice. If the glaze changes color, it indicates that the glaze can leach into the food, and it’s not food safe.

While leach testing is not a foolproof method, it is a quick and easy way to get an idea of a glaze’s acid resistance. If you are unsure of a glaze’s safety, it is always best to err on the side of caution and assume that it is not food safe.

Conclusion

Is pottery food safe without glaze? Unfortunately, the answer is not so simple. Unglazed pottery can be porous and absorb water as well as bacteria, mold, and fungus. While some unglazed pottery is considered food safe, it falls into the category of high fire Stoneware, Porcelain, or Ball clays that are waterproof and have a non-porous, glass-like surface.

However, imported, antique, and some hand-made pottery products do not have the decal declaring that it is not safe to be used with food. It is important to test all antique ceramics before using them in the kitchen as they may contain lead. With these potential dangers, it might be best to make or invest in pottery that is safe to use with food. If you are a potter, these are things to keep in mind when making dinnerware pottery.

FAQ

Is Air Dry Clay Safe for Food?

Air dry clay is a popular choice for crafting, as it is relatively inexpensive and easy to use. However, it is important to note that air dry clay is not safe for food. This means that you should not use it to create mugs, bowls, or plates that will be used for eating or drinking.

While the clay is safe to touch, it is not waterproof, even when using a sealant. The sealant can make the clay water resistant but not waterproof. In addition, air dry clay is not as durable as other types of clay, so it is more likely to break or chip when used for functional items. Therefore, you should only use air dry clay for decorative purposes.

Air dry can also be used on the pottery wheel. Find out which one is best by reading 3 Air Dry Clay Brands Tested on The Pottery Wheel.

Are Matte Glazes Food Safe 

When it comes to food safety, it is always better to err on the side of caution. While there are many matte glazes that are perfectly safe for use with food, there are also several potential dangers to consider. For instance, some matte glazes may contain heavy metals that can leach into food. In addition, matte glazes can be more porous than their glossy counterparts, which means they may absorb bacteria and contaminants from the food they come into contact with.

As a result, it is always best to use only food-safe glazes on dinnerware and other items that will come into contact with food. Luckily, many manufacturers now produce food-safe Matte Glazes, so finding a food safe matte glaze is easy.

How Do I Know if My Pottery Is Microwave Safe?

To find out if your pottery is microwave safe, look for a “microwave safe” label or wave symbol on the bottom of the piece. If there is no label or symbol, it is best to assume that the pottery is not microwave safe and to reheat food in it cautiously.

When in doubt, always err on the side of caution and reheat food in microwave-safe dishes only. If you are unsure whether a particular piece of pottery is microwave safe, you can test your pottery.

Place the pottery filled with water in the microwave for a minute. If the pottery feels warmer than the water, the pottery has absorbed more of the heat and is unsafe for microwaves. For more detailed information, check out this article on Microwave Safe Pottery.

Are Crackle Glazes Food Safe

Crackle glazes are a type of ceramic glaze that is known for its unique “crackled” appearance. Unfortunately, while crackle glazes can be beautiful, they are not food safe. This is because many crackle glazes can leach metals into food and drink, and they can also harbor bacteria.

By adding a layer of Clear Glaze over the pottery, you can create a barrier that will prevent contaminants from coming into contact with food or beverages. Clear glazes are also non-porous, so they won’t absorb bacteria like crackle glazes. As a result, adding a layer of clear glaze is an effective way to ensure that your pottery is food safe.