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Heat-resistant dishes and ordinary plates may look similar at first glance, but they differ significantly in materials, manufacturing methods, and intended use. This article explains the fundamental differences between the two types of tableware, focusing on how their design and production affect safety, durability, and suitability for cooking or serving.

Table of Contents
1.　Why Heat-Resistant Dishes and Ordinary Plates Are Often Confused
2.　Decisive Differences Seen in Materials
3.　Manufacturing Heat-Resistant Dishes: Processes That Prioritize Heat Resistance
4.　Manufacturing Ordinary Plates: Processes That Emphasize Usability and Aesthetics
5.　Conclusion: Choosing Tableware Based on Intended Use

Why Heat-Resistant Dishes and Ordinary Plates Are Often Confused

In recent years, oven cooking and microwave heating have become commonplace in households. As a result, opportunities to see so-called “heat-resistant dishes” have increased, many of which look no different from ordinary tableware at first glance. This has led to common assumptions such as “a thicker plate should be safe” or “ceramic plates are probably heat-resistant.”

In reality, however, heat-resistant dishes and ordinary ceramic plates differ significantly beneath the surface. Their materials and the way they are designed to be used are fundamentally different. Understanding these differences is important not only for safety but also for using tableware appropriately and for a long time.

Decisive Differences Seen in Materials

The materials used for heat-resistant dishes are clearly different from those used for ordinary ceramics and porcelain. The most distinctive feature is the use of lithium-based minerals such as petalite and spodumene as primary raw materials. These minerals have extremely low thermal expansion, meaning they undergo minimal dimensional change even when exposed to rapid temperature fluctuations. This property allows heat-resistant dishes to withstand being taken directly from an oven without cracking.

In addition, materials such as alumina, silica, and refractory clays are combined to enhance strength and durability. From this perspective, the material composition of heat-resistant dishes can be seen as closer to that of industrial heat-resistant materials than conventional tableware.

By contrast, ordinary plates made of earthenware or porcelain are formulated with an emphasis on texture, whiteness, ease of forming, and visual appeal. Earthenware typically consists of clay combined with feldspar and quartz, while porcelain is mainly composed of kaolin, feldspar, and quartz. These materials provide sufficient strength for daily use, but they are not designed to suppress thermal expansion to the same degree as heat-resistant dishes. As a result, they are more susceptible to cracking or damage when subjected to sudden heating or cooling.

Manufacturing Heat-Resistant Dishes: Processes That Prioritize Heat Resistance

In the manufacturing of heat-resistant dishes, resistance to cracking is the top priority. At the raw material stage, lithium-based minerals are carefully blended to create a body with minimal thermal expansion. The proportions used are highly sensitive, and even slight variations can significantly affect heat resistance. Maintaining consistent quality therefore requires precise control.

During forming, methods such as slip casting or press molding are commonly used, with particular attention paid to achieving uniform thickness. Variations in thickness can create internal stress, increasing the risk of breakage during heating. The drying process is also conducted slowly and carefully to prevent residual distortion or internal stress.

Firing is carried out at high temperatures of approximately 1,200 to 1,300 degrees Celsius, with both heating and cooling performed gradually. The glazes used are also low-expansion types, carefully matched to the body to ensure compatibility. By precisely aligning the thermal expansion of the body and glaze, problems such as peeling or crazing during heating are prevented.

Manufacturing Ordinary Plates: Processes That Emphasize Usability and Aesthetics

In contrast, the manufacturing of ordinary plates places greater emphasis on ease of use, design, and production efficiency rather than heat resistance. A wide range of forming techniques, including wheel throwing and press molding, are employed, allowing for greater freedom in shape and surface expression. Drying and firing processes do not require the same level of strict temperature control as heat-resistant dishes, and glaze selection prioritizes color, texture, and finish.

Earthenware is typically fired twice—once for bisque firing and again for the final firing—resulting in a warm, natural appearance. Porcelain, on the other hand, is fired at higher temperatures to produce a dense and hard body, enabling thin and lightweight forms. These manufacturing approaches are optimized for serving and presentation at the dining table and do not necessarily assume use over direct heat or in ovens.

Conclusion: Choosing Tableware Based on Intended Use

The difference between heat-resistant dishes and ordinary tableware lies not simply in their thickness or appearance, but in the materials used and the design philosophy based on how they are intended to be used. Heat-resistant dishes are made with lithium-based minerals that minimize thermal expansion, allowing them to withstand high temperatures during cooking. In contrast, ordinary ceramic and porcelain tableware is designed with an emphasis on the beauty of the clay and glaze, lightness, and ease of everyday use, and is therefore not suitable for sudden temperature changes.

Choosing tableware based on its intended use—whether for cooking or for serving—leads to a safer and more comfortable dining experience. When purchasing heat-resistant dishes, it is advisable to check product labels carefully for indications such as “oven-safe” or “safe for direct flame” to ensure they are suitable for the intended cooking method.

Imoto Sangyo offers a wide range of products, including heat-resistant dishes, as well as ceramic tableware, Japanese-style dishware, and kitchen goods from various regions of Japan. For more details, please visit our “Goods & Cases” page.