What is
borosilicate glass?

Teapots, double-walled glasses, oven dishes and laboratory glassware are made of borosilicate. It can go from the freezer to boiling water without breaking. Read on to learn what borosilicate glass is, why it is heat-resistant, how it differs from ordinary and tempered glass, and what to look for when buying and washing it.

Barely expandsFrom freezer to boilingLight and thin
Hot coffee in a heat-resistant glass
BOROSILICATE ✶ HEAT-RESISTANT ✶ DOUBLE-WALLED ✶ TEA GLASS ✶ GLAZEN.NL ✶

What is borosilicate?

Borosilicate glass is glass in which some of the soda has been replaced with boron oxide. As a result, it expands by only a third as much as ordinary glass when heated. That expansion is what causes ordinary glass to crack: the side in contact with hot water expands while the rest does not, and the resulting stress breaks the glass. Borosilicate expands so little that it handles this temperature difference without any problems.

It was developed in the late nineteenth century for laboratories and found its way into kitchens as Pyrex and Jenaer Glas. Today, it's the standard material for double-walled glasses, teapots, coffee pots and French presses.

Borosilicate, tempered or ordinary glass?

Ordinary glass cracks with a temperature difference of about 40 degrees, so pouring boiling water into a cold glass is risky. Tempered glass is stronger and can handle greater differences, but it's still ordinary soda-lime glass that expands. Borosilicate can handle a difference of up to 160 degrees, which is why it's the choice for anything that holds boiling water.

The downside: borosilicate is less impact-resistant than tempered glass. It is more likely to break if dropped, and into sharp shards. That's why you'll find it at home and in coffee shops, but less often on patios. Read about tempered glass and other materials in our article on tempered, crystal or shatterproof glass.

Double-walled glasses

Double-walled glasses are almost always made of borosilicate because it can be blown thin and must withstand the heat of coffee or tea. There is air between the two walls, keeping the outside cool and the drink warm for longer. It also makes the coffee look like it's floating.

Be careful when putting double-walled glasses in the dishwasher: most are dishwasher-safe, but water can get between the walls through the small hole in the bottom. Any droplets left behind will evaporate on their own. You can find all sizes in double-walled glasses.

The right glass

Luigi Bormioli’s Thermic glasses are double-walled borosilicate, hand-blown. Here are the 34 cl latte macchiato glass and the 22 cl tea glass, both sold in pairs. Find all sizes in the double-walled glasses collection.

Luigi Bormioli Thermic Latte Macchiato Glass 34 cl (2 pieces)
Our pick 01

Luigi Bormioli Thermic Latte Macchiato Glass 34 cl (2 pieces)

€ 24,95per set · fast delivery on business days
Luigi Bormioli Thermic Tea Glass 22 cl (2 pieces)
Our pick 02

Luigi Bormioli Thermic Tea Glass 22 cl (2 pieces)

€ 22,95per set · fast delivery on business days

Good to know

Can borosilicate glass go in the microwave?

Yes, as long as it has no metal parts. It’s also safe for the oven and freezer. Just don’t place it directly on a gas burner or cooktop.

How can you recognize borosilicate glass?

It is lighter and thinner than regular glass of the same size and has a subtle blue-gray tint around the edge. Manufacturers usually state this on the packaging.

How do you wash double-walled glasses?

Ideally, wash by hand in lukewarm water. It can go in the dishwasher, but place it upright and don’t use the hottest setting. Don’t leave it to soak in the sink.

Frequently asked questions

What is borosilicate glass?

Glass containing boron oxide that barely expands when heated, allowing it to withstand large temperature differences. It is used to make teapots, double-walled glasses, and laboratory glassware.

Can borosilicate glass withstand boiling water?

Yes. It can handle a temperature difference of about 160 degrees, including going from the freezer to boiling water. See our double-walled glasses.

What is the difference between borosilicate and tempered glass?

Borosilicate handles heat better, while tempered glass is more resistant to knocks and drops.

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