"Glass" on a product page can mean three different things. They behave differently when you pour boiling water into them, or move them from the fridge to the oven.
The three kinds you'll meet
- Soda-lime glass. The common one: bottles, drinking glasses, most jars, and much food storage. It's inexpensive, clear, and recyclable, and it's more sensitive to sudden temperature change than borosilicate. Fine for cold and room-temperature use, and for gradual heating.
- Borosilicate glass. It contains boron oxide, which lowers its thermal expansion, so it tolerates sudden temperature changes much better. This is the glass of laboratory beakers, many coffee servers and pour-over drippers, and siphon brewers. For a given strength it's lighter, and it usually costs more.
- Tempered (toughened) glass. A heat treatment, usually applied to soda-lime glass, that puts the surface in compression. The glass itself is the same. Tempered glass resists impact and moderate thermal shock better than untreated soda-lime. When it does break, it tends to crumble into small pieces rather than shards. It can't be cut or drilled after tempering.
There's a fourth term too. "Heat-resistant glass" is a marketing phrase, not a composition. It usually means borosilicate, but sometimes it means tempered soda-lime. Ask.
What the makers in our research state
| Product | Glass stated | Where made (stated) |
|---|---|---|
| Yama Glass siphons and servers | Heat-resistant borosilicate glass | Taiwan (brand description) |
| Hario V60 glass products | "Heatproof glass" made in Hario's own Japanese factory; composition not named on the pages we read | Japan |
| Lifefactory 16 oz bottle | Soda-lime glass made in France (stated on the replacement bottle page); some sizes reported as borosilicate | France |
| Duralex | Tempered glass, stated as 2.5 times stronger than untempered; composition not named | France |
| Anyday food storage | Glass described by the brand as oven and freezer safe; composition to be confirmed from the maker before we list it | United States company; manufacturing origin to confirm |
| Libbey | Brand statement: lead-free and cadmium-free; glass type not named | Varies by product. Libbey lists a country for each item: mostly United States (Toledo, Ohio) or Mexico |
Four of the six makers in that table don't name the glass composition. They tell you about heat, strength, origin or lead instead.
Our profiles record exactly what was stated. The rest is marked "not stated."
Lids, seals, and rims
Glass storage is rarely all glass. Lids are usually polypropylene, sometimes bamboo or stainless. The seal is usually silicone.
The lid and seal are the parts that touch food when the container is full or inverted. So a "glass" container's material profile has three lines, not one.
Decorated glass, like printed logos or colored rims, has a second material on it: the decoration. That's why lip-and-rim testing exists for decorated drinkware.
Practical guidance from the makers' own care pages
- Don't pour boiling water into cold soda-lime glass, and don't put hot glass on a cold wet surface.
- Borosilicate tolerates sudden heat far better, but it still breaks on impact, and thin walls chip at the rim.
- Retire tempered glass once it's chipped. The surface compression that makes it strong is also why a chip can spread suddenly.
- Follow the maker's oven, freezer, and dishwasher limits exactly. Our product pages quote them.
Reviewed: 2026-10-15.
Read next: What the number in the triangle on your lid means and Which parts of a French press touch your coffee.