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Material: Some glasses are made from special materials that have a high resistance to heat. For example, borosilicate glass, commonly used in laboratory glassware, has a low coefficient of thermal expansion, making it more resistant to thermal stress and less likely to break when exposed to high temperatures.
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Annealing: Glasses that are properly annealed during the manufacturing process are less likely to break when heated. Annealing involves slowly cooling the glass to relieve internal stresses and increase its strength. This process helps to prevent the formation of weak spots that could lead to breakage when exposed to heat.
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Tempering: Tempered glass is treated with a special heating and cooling process that increases its strength and resistance to thermal stress. When tempered glass is heated, it expands more uniformly, reducing the likelihood of breakage. This type of glass is commonly used in cookware and oven doors.
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Design: The design of the glassware can also contribute to its ability to withstand heat. Glasses with thicker walls or reinforced areas are less likely to break when exposed to high temperatures. Additionally, the shape and structure of the glass can distribute heat more evenly, reducing the risk of thermal stress and breakage.
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Coatings: Some glasses may have protective coatings or layers that enhance their heat resistance. These coatings can provide an additional barrier against thermal stress and prevent the glass from breaking when heated.
Overall, glasses that do not break when heated are typically made from specialized materials, undergo specific manufacturing processes such as annealing or tempering, have a suitable design, and may have additional coatings or layers to enhance their heat resistance.