Borosilicate glass

What it is

Borosilicate glass is glass made with boron oxide, the kind used for lab beakers, coffee carafes and many glass lids. It shrugs off sudden temperature changes that would crack ordinary glass, and it still breaks when you drop it.

Why it matters in your kitchen

Picture pouring water just off the boil into a glass carafe. Ordinary glass can crack from that jolt. Borosilicate barely notices.

The reason is expansion. On SCHOTT's data sheets, borosilicate expands about a third as much as everyday soda-lime glass when it heats (3.3 against 9.1, in millionths per degree Celsius), so a fast change builds less strain.

It's still glass. A knock against the faucet chips a thin rim, and a drop on tile ends it.

Good at

• Hot pours and quick temperature swings. That's its job: carafes, pour-over servers, siphon brewers and lids that sit over steam.
• Coffee, tomato and vinegar. SCHOTT puts its borosilicate in the top class for resistance to water and acids, so everyday food doesn't etch it.
• Watching a simmer. A glass lid lets you check the pot without lifting it. The 1826 glass lid we sell is borosilicate and goes in the oven to 400°F, per Cristel.

Watch for

• It breaks on impact. Handling heat well doesn't mean surviving a fall. Set it down gently and keep it out of a crowded sink.
• Thin rims chip. Carafes and servers have thin lips. Dry and store them where the rim won't knock against other glass.
• "Heat-resistant" may mean something else. Some glass sold as heat-resistant is tempered soda-lime. Ask which glass it is, and follow the maker's oven and stovetop limits either way.
• Recycling bins often refuse it. Many programs won't take it with bottles and jars, because it melts at a different temperature. Check your local rules.
• It usually costs more. You're paying for the heat tolerance. For cold storage, everyday glass does the same job.

Who it suits

Good for you if you pour boiling water, brew coffee in glass or like to watch a pot through the lid. Skip it where the glass will get knocked around, like a camping kit, where stainless holds up better.

In short. Borosilicate glass handles sudden heat far better than everyday glass and resists acids and stains, and it still breaks if you drop it.

Our guide to glass types compares borosilicate, soda-lime and tempered glass. For what research has and hasn't shown about cookware materials, see our guide.

Where it is used

• Pour-over drippers and coffee servers
• Siphon brewers
• Glass lids, including the Cristel 1826 lid we sell
• Some storage and bakeware

How to care for it

• Follow the maker's limits for the oven, stovetop and dishwasher. It tolerates sudden heat well, not without limit.
• Keep thin rims away from the faucet and other glass. That's where it chips.
• Retire a piece with a crack or a deep chip.