If you have made pottery before. Then you have had the chance to feel and manipulate the clay that potters use. But, have you ever wondered what is potters clay made of? If you have ever asked yourself that question, this article can help you find the answer.
Pottery clay ingredients are made up of various minerals and organic materials that are mixed together to create a workable substance. Clay is also found ready-made by the earth. Depending on the location and climate where the clay is mined, the type of clay will be different. The most popular types of pottery clay are earthenware, stoneware, and porcelain.
Keep reading to learn more about different clays and the composition of the clays.
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What Is Pottery Clay
Pottery Clay is made up of very tiny particles or (platelets) that are flexible but tough. The shape of the clay particle is flat and wide.
You can’t see them with the naked eye except for the sand particles in the clay. You can see the clay and silt only throw a microscope. The clay particle size measure around 0.002 mm or smaller. While the silt in the clay can measure between 0.002 to 0.05 mm.
Because of the variety of minerals and raw materials, there are many different clay bodies to choose from.
Water is also an essential component of clay. When the clay particles get moist, they stick to each other. This is what gives the clay the ability to be molded.
How the Earth Produces Clay
The earth actually does the majority of the production of the clay that is used for pottery. Over the span of hundreds of years, rock minerals have been eroded by natural elements such as wind and water that create the tiny particles. Rocks that are silicate-bearing eventually break down to the point that they form sediments. The sediments then come together to make clay particles.
The majority of those particles stay together, becoming dense, heavy, and vary in color. If the clay is found and has no debris in it, it is considered “pure.” However, if it has debris that makes the texture rough, it has moved from its original location and is not “pure.”
This categorizes clay into two categories: primary and secondary. Primary clay is found and collected at the spot of formation with no debris included. Secondary basic clay is found at a different location than where it was formed and has debris in it. Primary clay is what is most desired when collecting clay for pottery, as that will create a smooth, easily manipulated clay.
How Is Clay Made for Pottery
Now that the clay base has been found and collected, it is ready to be made into pottery clay by adding aluminum silicates, organic materials, and water. If you were to try and use the secondary clay just as it was when it was collected, it would not mold and hold as you would like it to.
Once the clay has been collected, it is partially air-dried. At this point, when the clay is halfway dried, it can be assessed by color and consistency so it can be classified as the appropriate type. This process is done with each load of clay collected to ensure consistent results in the clay collected and used. After the clay has been assessed and classified, it is put into a revolver tank to further smooth it out to prepare it for molding and pottery use.
The clay will then go through a process called “flash-drain.” The clay is heated in a furnace and will dry the clay out, so there is only 1-2% moisture left. The dried-out clay is then pulsed into a fine powder. Then the pulverized clay is tested by assessing the color. When the clay is ready to use, it can be rehydrated by being mixed with water to reinstate it to its malleable, pliable state.
Different Pottery Clay Types – Their Ingredients and Properties
Now that you know how pottery clay is made and what it’s made of, you might wonder what the different types of clay are. Below is a list of the Main Types Of Clay Used To Create Pottery, with a brief explanation of each.
What Is Earthenware Clay Made Of
Earthenware clay, also known as common clay, is one of the most popular types of pottery clay. It is a type of clay that can be found in nature. It is considered to be a secondary type of clay, meaning the clay was not found in a pure state and contains iron and other mineral impurities. Earthenware clay comprises various minerals mixed together to create a workable substance.
Depending on the ingredients of soil, location, and climate where the clay is mined, the clay types will be different. The breakdown of earthenware ingredients includes kaolinite ( hydrous aluminum silicate ), feldspar (used as a flux), calcium carbonate (filler to reduce fired shrinkage), and quartz (silica).
Because there are many low-fire clay bodies to choose from, the ingredients and additives will vary, like adding iron or talc.
Earthenware Clay Properties:
Earthenware fires to low temperatures. It is commonly fired between 1828°F ( 998°C ) Cone 06 and 1945°F (1063°C) Cone 04. The lower temperature is more energy-efficient but is porous and does not vitrify when fired.
The texture of this clay is highly plastic, which has a sticky and easily malleable feel. This type of clay is eye-catching due to the variety of colors. It typically comes in red, orange, brown, terracotta, white, and light gray.
Earthenware is used for sculpting, hand-building, and wheel throwing. In addition, you can create sculptures, flowerpots, and other types of pottery like coffee mugs.
What Is Stoneware Clay Made Of
Stoneware is another popular clay due to its plasticity and durability. This clay is mainly ball-clay-based instead of kaolin-based. Stoneware also contains kaolinite (aluminum silicate), feldspar (used as a flux), and quartz (silica).
Other clay minerals are added like bentonite, iron impurities, and small quantities of mica, Illite, and smectite. That’s why there are so many different stoneware clays to choose from.
Stoneware Clay Properties:
Stoneware is fired to high temperatures. The temperature range is typically from 2,167°F (1,186°C) Cone 5 to 2,345°F (1,285°C) Cone 10.This firing process gives the pottery a harder, more nonporous, durable finish. This makes Stoneware Clay a popular clay to use for practical uses like tableware.
Stoneware varies in color from white, grey, and all the way to brown when wet. It is basically smooth clay unless sand or grog is added.
Stoneware clay’s plasticity is good, making it easy to work with. It is mainly used in hand-building and Throwing on the Wheel.
What Is Porcelain Clay Made Of
Porcelain is made of a large part of pure kaolin (kaolinite), ball clay, feldspar (used as a flux), and quartz (silica). The porcelain clay body can be mixed with various minerals to fire to a lower temperature and increase workability.
Like the earthenware and stoneware clays, there are different types of Porcelain clay bodies.
Porcelain Clay Properties:
Porcelain Clay is mainly fired to higher temperatures of 2,345°F (1,285°C) Cone 10 for the best results. However, Europeans invented a clay body that fires at lower temperatures (about 2167℉ or 1186℃) Cone 5. Therefore, the soft-paste porcelain is considered weak porcelain.
Porcelain is primarily an off-white to white clay. It is very smooth, like butter. This clay is more elastic and less plastic, making it harder to work with. The main reasons porcelain clays are not recommended for beginner potters is because of their low plasticity (difficulty shaping) and difficulty with throwing on the wheel and hand-build without the clay collapsing.
It is generally used in Slip Casting and wheel throwing to create vases, tableware, and other decorative objects.
What Is Bone China Clay Made Of
Bone China clay is a type of porcelain clay. It is made mainly of Pure kaolin (kaolinite), bone ash (animal bones), and quartz (Silica)
Bone China Clay Properties:
Bone China’s melting point is very high. It fires to maturity at about 3272 F (1800 C), which is Cone 36 but is generally fired to 2,345°F (1,285°C) Cone 10.
Bone China clay was first used in China over 2000 years ago to make porcelain. The main characteristic of this clay is its white color. When wet, it is a creamy white color, and when it is fired, it is pure white.
It has a very fine texture and is quite soft. It is also used mainly in wheel throwing and slip casting to create tableware, vases, and other decorative objects.
What Is Ball Clay Made Of
Ball clay made is of kaolinite (aluminum silicate), mica, and quartz( Silica). It may contain a few mineral impurities, making the clay ideal for an additive to other clay bodies.
Ball Clay Properties:
Ball clays fire to their mature hardness at 2,345°F (1,285°C) Cone 10.
When moist, ball clays are dark grey in color. When fired, they are a light grey.
Ball clays are highly plastic but tend to be too fine and slippery for use alone. It also has a high shrinkage rate. That is why it is mainly used in slip casting.
Importance of How to Choose the Right Pottery Clay for Your Project
When choosing clay for your project, it is important to consider the following factors. The type of project you are working on, the firing temperature of the clay, and the plasticity of the clay. As you can see, each type of clay has its own unique characteristics that can affect the final product.
When starting out in pottery, it is important to understand the different types of clays available and how to choose the right one for your project. For more detailed information on which clay is best for you, Read Choosing Your Pottery Clay – For Beginners. Or check out this Video👇
In short, pottery clay is made of various minerals that are mixed together to create a workable substance. Depending on the location and climate where the clay is mined, the type of clay will be different. The most popular types of pottery clays are earthenware, stoneware, and porcelain. Each type of clay has its own unique characteristics that can affect the final product. When starting out in pottery, it is important to understand the different types of clays available and how to choose the right one for your project. With a little bit of knowledge, you can be sure to create a beautiful and unique piece of pottery.
What Clay Is Used For
Clay is a type of mineral that is found in many different places around the world. It is often used in pottery and ceramics, as it is easy to mold and shape. Clay can also be used for building materials, such as bricks and tiles.
It is also used in various industries, including the manufacture of paper and textiles. In addition, it is sometimes used in cosmetics and medicines. There are many different types of clay, each with its own unique properties. As a result, clay can be used for a wide variety of purposes. Whether you are an artist or a builder, there is sure to be a type of clay that meets your needs.
How to Store Pottery Clay
How you store your pottery clay can mean the difference between success and failure when it comes time to use it. There are two main ways to store pottery clay – tightly sealed or in dry form. Each has its own benefits and challenges.
Tightly sealing your pottery clay is the best way to preserve its moisture content. This is important if you want to avoid having to add water to your clay when you’re ready to use it. However, tightly sealing your clay can also lead to mold growth if not done properly. So be sure to check your seal regularly and release any built-up moisture before it has a chance to cause problems.
Storing your pottery clay in dry form is another option. This allows you to store your clay for longer periods of time without worrying about it drying out or growing mold. However, you will need to rehydrate your clay before using it, which can be challenging if not done right. Before attempting this storage method, be sure to research how to properly rehydrate your particular type of pottery clay.
For more detailed information, read about How to Store Pottery Clay.
Where to Find Pottery Clay in Nature
One of the most important materials for pottery is clay, which can be found in its raw state in many places around the world. In general, clay is found near water sources, as it is often formed from deposits of sediment. For potters who are looking for local clay, there are a few places where it is known to occur.
One option is to look for alluvial (loose clay, silt, or sand) deposits often found along riverbanks or in floodplains. Another option is to look for exposed shale bedrock, which sometimes contains clay deposits. Finally, some potters source their clay from weathered volcanic ash, which can be found in many parts of the world. With a little patience and effort, any potter can find the clay they need to create beautiful works of art.
The History of Pottery Clay and Its Uses Throughout the Centuries
Pottery clay has been used throughout the centuries for a variety of purposes. Its importance can be traced back to some of the earliest civilizations.
One of the earliest known examples of pottery is a vessel found in Mesopotamia that is believed to date back to 6,000 BC. This pottery was made from a type of clay that was local to the area. In addition, the clay was fired at a high temperature, resulting in a durable product.
Over the years, pottery clay has been used for various purposes. It has been used to make pots, plates, bowls, and other household items. In addition, it has been used to make bricks, tiles, and other building materials. Potters have even used it to create sculptures and other works of art.
Clay is an important material because it is durable, versatile, and easy to work with. It has been used by potters for centuries to create beautiful and lasting pieces of art. As a result, it is an important part of our history and culture.