Pyrometric cone

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Figure 6

Segerkegel

Pyrometric cone

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Pyrometric cones in use

A pyrometric cone is a device used to gauge the heatwork (the combined effect of time and temperature) in a kiln during the firing of ceramic materials. These cones are made from carefully formulated compositions of ceramic materials, which are designed to melt and bend at specific temperatures. Pyrometric cones are essential tools in the field of ceramics and are widely used by potters and industrial manufacturers to ensure the proper firing of their products.

History

The development of pyrometric cones can be traced back to the late 19th century. They were invented by Hermann Seger, a German chemist, who sought a reliable method to measure the heatwork in kilns. Seger's cones, also known as Seger cones, became the standard for measuring kiln temperatures and are still in use today.

Function and Use

Pyrometric cones are placed in the kiln alongside the ceramic ware. As the temperature in the kiln rises, the cones absorb heat and begin to soften. Each cone is designed to bend at a specific temperature, providing a visual indication that the desired heatwork has been achieved. The bending of the cone is a result of the melting of the materials within the cone, which causes it to deform under its own weight.

Types of Pyrometric Cones

There are several types of pyrometric cones, each designed for different temperature ranges and firing conditions. The most common types include:

• Standard Cones: Used for general ceramic firing, these cones are available in a wide range of temperatures.
• Self-Supporting Cones: These cones have a built-in base, allowing them to stand upright without additional support.
• Junior Cones: Smaller versions of standard cones, used in small kilns or for testing purposes.

Temperature Ranges

Pyrometric cones are numbered to indicate their melting temperatures. The numbering system ranges from cone 022 (approximately 600°C) to cone 42 (approximately 2000°C). Lower numbers correspond to higher temperatures. For example, cone 06 melts at a lower temperature than cone 10.

Applications

Pyrometric cones are used in various applications, including:

• Pottery: Ensuring that glazes and clay bodies are fired to the correct temperature.
• Industrial ceramics: Monitoring the firing of bricks, tiles, and other ceramic products.
• Glass: Controlling the annealing and fusing processes.

Advantages

The use of pyrometric cones offers several advantages:

• Accuracy: Provides a reliable measure of heatwork, accounting for both temperature and time.
• Simplicity: Easy to use and interpret, requiring no complex equipment.
• Versatility: Suitable for a wide range of firing conditions and materials.

Related Pages

• Kiln
• Ceramics
• Pottery
• Glaze
• Firing (ceramics)
• Hermann Seger

See Also

• Thermocouple
• Kiln sitter
• Ceramic engineering