Porcelain Dishes: Built To Last?

Porcelain dinnerware is popular because it is both durable and attractive. The high-temperature firing process, which can reach up to 2,500 degrees Fahrenheit, makes porcelain non-porous, resistant to stains, and hard to chip or crack. This dinnerware can be placed in the dishwasher, microwave, oven, and freezer without damage. However, despite its durability, porcelain can break if dropped and can scratch if handled with metal utensils.

Porcelain's resistance to microwaves, ovens, freezers and dishwashers

Porcelain is a type of ceramic that is typically created with kaolinite, kaolin, or china clay. It is heated and shaped in a kiln at temperatures of around 2,600 degrees Fahrenheit, resulting in a dense and durable material. This process of heating and cooling means that porcelain is generally resistant to microwaves, ovens, freezers, and dishwashers.

Microwaves

Porcelain is generally safe to use in microwaves. However, there are some factors to consider. Firstly, if the porcelain has any painted designs, metallic decorations, or a decorative glaze, it is not recommended for microwave use as these can contain harmful chemicals or materials that may leech into your food. Secondly, avoid putting cold porcelain into the microwave, as it can experience thermal shock when transitioning from a cold to hot environment. Always allow porcelain to reach room temperature before placing it in the microwave. Lastly, white porcelain is the safest type of porcelain to use in the microwave, as it does not have any added colours, materials, or designs that may be affected by the microwave's heat.

Ovens

Porcelain is safe to use in ovens as it can withstand high temperatures. However, it is important to note that the same rules for microwaves apply to ovens. Avoid using heavily-designed or decorated porcelain dishes in the oven, as the heat may damage the designs or cause them to chip or crack.

Freezers

Porcelain is frost-resistant due to the high temperatures at which it is fired during the manufacturing process. Therefore, it is safe to use in freezers without worrying about cracking or breaking due to freezing temperatures.

Dishwashers

Porcelain is generally dishwasher-safe, but it is important to follow the manufacturer's instructions and use the correct detergents. White hard porcelain without decorations is always dishwasher-safe, as it does not have finishes that are subject to abrasion. However, the glaze, thickness, and quality of the porcelain will determine its resistance to mechanical and thermal stress in the dishwasher.

The high-temperature firing process

Preparation for Firing

Before the actual firing process, the porcelain products undergo a crucial preparation stage. The clay bodies are formed using techniques such as soft plastic forming, stiff plastic forming, pressing, or casting. The specific method depends on the type of ware being produced. Once the desired shape is achieved, the porcelain pieces are subjected to a preliminary firing step called bisque-firing. This step involves heating the ware at a relatively low temperature to remove volatile contaminants and minimise shrinkage during the subsequent high-temperature firing.

Firing Temperatures

The firing temperature plays a pivotal role in determining the final properties of porcelain. Porcelain is typically fired at extremely high temperatures, ranging from 2,372 degrees Fahrenheit to 2,650 degrees Fahrenheit (1,454 degrees Celsius). These high temperatures contribute to the strength and durability of the porcelain. The firing temperature for porcelain is significantly higher than that of other ceramics like earthenware and stoneware, which are fired at lower temperatures and exhibit lower durability.

The Firing Process

During the high-temperature firing process, porcelain wares are placed in a kiln, a specialised oven for firing ceramics. The kiln can be of different types, such as a periodic kiln or a tunnel kiln, each offering advantages in terms of flexibility or energy efficiency. The firing process involves a series of complex reactions, including the burning off of impurities, the evolution of chemical water, and the decomposition of carbonates and sulfates. The minerals within the clay body undergo changes, and the fluxes present, such as feldspar and flint, react to form liquid glasses. These glass phases are essential for shrinking and bonding the grains of the porcelain body.

Cooling and Glazing

After the desired density is achieved, the ware is cooled, causing the liquid glass formed during firing to solidify. This solidification results in a strong bond between the remaining crystalline grains, contributing to the overall strength of the porcelain. Once the porcelain has cooled, it undergoes a glazing operation, where a decorative glass layer is applied to the surface. The ware is then fired again, resulting in a hard, vitrified, non-absorbent clay body with a glaze that fuses with the clay body, creating a thin combined layer.

The Role of Temperature in Durability

Porcelain's durability compared to earthenware and stoneware

Porcelain, earthenware, and stoneware are all types of ceramics, which is an umbrella term for hard and durable yet brittle substances that all traditional pottery and dinnerware are made of. The differences between these three types of pottery lie in their durability and hardness.

Earthenware is the simplest type of ceramic available. It is made with the least refined clay body and fired at the lowest temperatures, between 1300°F and 2120°F. This type of ceramic is very porous, so it must be covered with a coat of glaze if it is to hold food or liquid. It is also quite fragile, and therefore not often used to present food.

Stoneware is harder and denser than earthenware and is fired at higher temperatures, between 2150°F and 2372°F. It is also less porous than earthenware, which makes it ideal for creating tableware and other vessels for eating and drinking. Stoneware is more durable than earthenware, but it tends to chip before it breaks.

Porcelain is the hardest ceramic and is fired at the highest temperatures, usually above 2300°F. It is made with a fine-particle clay that is typically comprised of feldspar, kaolin, and quartz. This makes porcelain extremely durable and nonporous. The high firing temperature also allows porcelain to have a thinner and more delicately constructed body, which gives it a translucent appearance.

In summary, porcelain is the most durable of the three types of ceramics, followed by stoneware, and then earthenware. Porcelain and stoneware are ideal for creating tableware, while earthenware is more suitable for decorative purposes.

The risk of scratching or chipping porcelain

Porcelain is highly durable and resistant to scratches and chips, but it is not completely impervious to them. The risk of scratching or chipping porcelain depends on several factors, including the quality of the porcelain, the glaze application, and usage and handling.

Firstly, the quality of porcelain varies depending on the manufacturer and the specific composition of the clay and minerals used. High-quality porcelain, often called fine china, tends to be more durable and scratch-resistant. It is important to ensure that the porcelain is made from the right clays and does not contain silica, quartz, or feldspar, as these can compromise its durability.

Secondly, the glaze application plays a crucial role in scratch resistance. The glaze on porcelain adds a protective layer, and a well-applied glaze can significantly enhance its resistance to scratches. Glazed porcelain is more widely used in interiors and offers a smooth, easy-to-clean surface. However, unglazed porcelain tiles are generally more resistant to scratches and are often used in flooring or outdoor applications due to their superior traction and slip resistance.

Lastly, frequent use and handling can increase the risk of scratches and chips. Stacking, washing, and using cutlery on porcelain can impact its surface. To minimise the risk, it is recommended to use gentle cleaning tools, stack plates with soft cloths or paper towels between them, choose cutlery made from softer materials, and wash with care, especially with older or more delicate pieces.

While porcelain is highly durable and resistant to scratches and chips, it is essential to handle it with care to maintain its beauty and extend its lifespan.

The advantages of bone china over porcelain

Bone china and porcelain are two different types of ceramics that are very similar in appearance. However, there are several advantages to choosing bone china over porcelain for your tableware.

Firstly, bone china is renowned for its exceptional durability. This is due to the addition of bone ash to its raw materials, which typically includes a percentage of around 30-45% bone ash, most often from cow bones. The bone ash content gives bone china greater strength and resilience than porcelain, making it less prone to chipping and breaking. This makes bone china ideal for everyday use, as it can withstand accidental slips and knocks, and is also chip-resistant.

Secondly, bone china has a more elegant and refined appearance than porcelain. Its colour is a creamy, soft white, with a delicate, milky texture that is more translucent than porcelain. This translucent quality makes bone china ideal for serving food, as it allows light to shine through, adding a touch of sophistication to your dining experience.

Thirdly, bone china is lightweight compared to porcelain, which tends to be significantly heavier. This makes bone china more suitable for use as tableware, as it feels more elegant and refined in the hand, enhancing the overall dining experience.

Finally, bone china is considered a luxurious and precious material due to its refined appearance and durability. It often has sentimental value and is passed down through generations, becoming a cherished family heirloom. Investing in bone china for your tableware can, therefore, be a wise decision, as it will last for decades and elevate your dining experience every day.

Frequently asked questions