There are a multitude of pots available that are made from different materials with the most common being pots made from clay. The different categories of clay pots are classified according to the temperatures they were fired in, the type of clay used, and the method in which they were made. Clay in its natural, raw form comes from the earth as a by-product of rock decomposition. The clay is mixed with various additives to be used as pottery clay, which is shaped, dried, and fired with or without a glaze.
You will find that pots are distinguished between earthenware, stoneware, and porcelain. Earthenware is less expensive, and the least durable out of the three as it’s made from a low-quality clay. Stoneware is more durable and more expensive, while porcelain is at the higher end being the most durable and most expensive as it’s made from the highest clay quality.
Clay purity and colour are important determining factors. For example, porcelain is made from a very pure clay. Different techniques are used to make clay pots such as by hand where it’s pinched into shaped, or on a pottery wheel for circular symmetry. And you can identify pots primarily through the surface texture. Earthenware feels chalky, stoneware is more sandy and gritty, while porcelain will be very smooth and thin and may even seem translucent at the edges.
Earthenware
Earthenware is commonly used as garden and patio planters. Pots classified as earthenware will often be made from a mixed clay recipe consisting of 25% ball clay, 25% China clay (Kaolin), 35% flint, and 15% China stone. They are fired in a kiln at temperatures ranging from 1100 to 1149° Celsius. It is slightly porous after the first firing and to be rendered waterproof, a glaze must be applied and then fired for a second time.
There are two different groups of glazed earthenware online pots. One is called creamware when a transparent lead glaze is added to cream coloured earthenware. The second is tin-enamelled, delft, majolica, or faience when an opaque white tin glaze is applied. Terracotta is an unglazed clay pot that typically has a rich brown, orange colour, and contains a lot of iron oxide.
Stoneware
Stoneware is popular for cooking and dinnerware and can be safely used for heating in ovens and microwaves, but you will also find an online pot in this category that will make a beautiful and durable planter. Stoneware clay ingredients are mostly made from ball clay but might contain some Kaolin. Stoneware is fired at a higher temperature than earthenware at around 1260° Celsius.
Because of its composition, stoneware has few impurities, and the finished product is waterproof, so glazing is optional for aesthetic purposes. Most stoneware is salt glazed, which is done by vaporizing salt during firing, which makes the sodium react to form a glassy coating.
Porcelain
To buy pots online classified as porcelain will be more expensive than other types of clay pots. Porcelain is made from pure Kaolin (China clay). Kaolin is mostly mined in Malaysia and England using high pressured hoses directed at the wall of the clay pits. A slurry is formed that is then washed down leaving most of the impurities behind. Kaolin needs very high temperatures to harden, which range between 1270 and 1400° Celsius.
While porcelain is very hard after firing, it can still be easily broken, which is why we think of porcelain as being fragile. After the pot is fired, the surface is shiny and smooth and does not require glazing. Fine China or Bone China are popular terms used to describe porcelain that has ground animal bone added to the clay to create a highly durable material.