Borosilicate glass is the type of glass used in laboratory beakers, original Pyrex baking dishes, and high-quality teapots. Its defining feature is thermal shock resistance — it can handle direct boiling water or a quick temperature change without cracking, which regular glass (soda-lime) cannot.
Why it matters
If you've ever poured boiling water into a regular glass and watched it crack, you've experienced the difference. Borosilicate glass contains boron trioxide instead of soda ash and lime, which gives it three key properties:
- Low thermal expansion — barely expands when heated, so it doesn't crack from temperature gradients.
- Chemical inertness — doesn't leach into food or drink at high temperatures.
- Mechanical durability — more resistant to thermal shock than tempered soda-lime glass.
Where you'll find it
- Laboratory glassware (beakers, flasks, test tubes)
- High-end teapots and coffee makers — the Pindefang Hammered Teapot is an example
- Original-formulation Pyrex (modern Pyrex varies by region)
- Heat-resistant water jugs and carafes
- Some cooktop-safe cookware
How to tell if glass is borosilicate
Visually it looks the same as regular glass. The reliable signals are:
- The product description explicitly says "borosilicate".
- The product is rated for direct boiling water or flame contact.
- It's slightly more expensive than soda-lime alternatives.
If a product says only "heat-resistant glass" without naming borosilicate, treat it as tempered soda-lime — fine for warm drinks but risky for sudden boiling-water pours.
Related reading
Full borosilicate glass buying guide · Kitchen & Dining at Maliben