Bodum Thermal Glassware Details Page

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I enjoyed these new hand-blown, double-wall insulated glass cups for 4 weeks until I finally broke one. It was inevitable. In slow-motion, I watched the demitasse Assam cup roll off the table, drop 2 feet onto a wood board without breaking, then drop aother foot onto the concrete floor. That was that. When glass meets concrete, you know who wins. But I was surprised to see how it bounced off the wood surface without breaking and realized it is because the cups are lab glass (Borosilicate).

*Note: 9 ounce size (middle cup shown above) no longer stocked
More about the glass used in the double-walled cups from Bodum: Bodum's insulated glassware is made from durable Borosilicate glass. Borosilicate glass is a strong heat-resistant glass that weighs less than traditional glassware. Used to make scientific lab glass, borosilicate glass (medical grade glass) is stronger than traditional "soda-lime" glass and can be used for everything from drinkware to cookware. Borosilicate glass substitutes boron oxide in place of the soda and lime used in traditional glassware. The boron oxide acts as a glue holding the silicate together and due to the small size of boron particles, the glass is held together tighter, resulting in a stronger glass. Some customers may perceive the glass to be "thin" as they hold it. It is important to explain the difference between borosilicate and soda lime glass. Borosilicate glass doesn't need to be as thick as traditional glass to be just as strong. Borosilicate is simply a different type of glass that is resistant to temperature swings and scratching. Because the particles are held together so tightly, borosilicate glass is dishwasher safe and will not become cloudy over time; you can rest assured that after 100 cycles, the glass will be as clear as the day you bought it. Simply treat it as you would any glass product and it will stand up to every day use. Dishwasher & microwave safe. Instructions for use: Bodum insulated, double wall glass is handmade by expert artisans, so they say. Because this glass is mouth-blown (their term, not mine!), each one may have slight differences in height, thickness & weight. Please use care when placing ice into the glass to avoid fracturing the inner layer. Please also avoid using metal spoons or placing the glass into a crowded dishwasher. These glasses will help to keep hot drinks warmer and cool drinks cooler. For best results retaining heat, pre-heat the glass before use. Dishwasher & microwave safe.

Side by side comparison of the 2 sizes