Why Some Glass Survives the Freezer (and Yours Can Too)

You can freeze food in glass containers, but only if you use the right type of glass, like borosilicate or tempered, and follow specific techniques. Proper preparation, including cooling food and leaving room for expansion, along with gradual thawing, prevents breakage.

Darius Williams

November 7, 2026 · 4 min read

Yes, you can freeze food in glass — but only in the right glass, and only with the right technique. The containers that shatter in freezers are almost always regular annealed soda-lime glass hit by thermal shock; the ones that survive are borosilicate or tempered glass, handled with a few simple precautions. Get the glass type right, leave room for expansion, and thaw gradually, and glass becomes one of the best freezer tools you own.

Understanding Glass Types: Why Some Withstand the Cold

Let's start with the villain: thermal shock. When glass faces a sudden temperature swing, one surface expands or contracts faster than the other. That uneven movement creates internal stress, and if the stress exceeds what the glass can absorb, it cracks — sometimes violently. I've seen the aftermath described as a freezer that "looked like a crime scene" after a hot chili jar went straight into the cold. Not fun.

How well a glass handles that stress comes down to one number: its coefficient of thermal expansion. That's simply how much the material grows or shrinks per degree of temperature change. The lower the number, the less the glass moves when temperatures swing, and the less internal stress it experiences.

Borosilicate glass is the champion here. It's an engineered glass — silica combined with boron trioxide as the main glass-forming components — originally developed for laboratory conditions too harsh for household glass. According to the widely cited technical description of the material, borosilicate has a very low coefficient of thermal expansion, roughly 3 × 10⁻⁶ K⁻¹ at 20 °C, and can withstand temperature differentials of about 330 °F (166 °C) without fracturing. In plain terms: it barely flinches going from freezer to heat and back.

Tempered glass is a different route to the same destination. It starts as regular soda-lime glass, but a controlled tempering process strengthens it, boosting both its durability and its resistance to temperature changes. Kitchenware makers like de Buyer note that tempered glass is considered freezer-safe and can stay in the freezer indefinitely without degrading — though food quality still depends on storage time, airtight seals, and stable freezer temperatures.

Then there's regular annealed soda-lime glass — the everyday stuff. It's the most commonly produced glass in the world, made primarily of silica (about 70–75%) along with sodium oxide and calcium oxide. It's chemically stable and durable for ordinary use, but it lacks boron's low-expansion chemistry and hasn't been tempered, so it carries a higher expansion coefficient and much less tolerance for thermal stress. This is the glass that cracks or shatters when it meets rapid temperature changes. If your container doesn't say borosilicate, tempered, or freezer-safe, treat it as this category.

One practical note: don't rely on brand names alone. Some newer Pyrex-style dishes are borosilicate; older or other lines may be tempered soda-lime. Check the label for the actual glass type or a freezer-safe marking.

Step-by-step safety checklist for freezing and thawing food in glass
Phase	Action	Scientific Reason
1. Select	Use only borosilicate, tempered, or explicitly freezer-safe labeled glass	Low thermal expansion (borosilicate) or strengthened structure (tempered) resists thermal shock; annealed soda-lime glass does not
2. Cool	Let hot food cool to room temperature first	Prevents a sudden temperature differential between the hot contents and the cold freezer environment
3. Fill	Fill containers only about 3/4 full	Liquids expand as they freeze; headspace gives that expansion somewhere to go instead of stressing the walls
4. Chill	Refrigerate before transferring to the freezer	Gradual temperature steps reduce thermal stress on the glass
5. Seal	Seal containers tightly	Airtight seals preserve food quality during storage
6. Thaw	Move to the refrigerator or let rest at room temperature; never use hot water or direct heat	Slow, gradual warming keeps the temperature differential within the glass's tolerance

Safe Thawing Techniques for Frozen Glass

Thawing is where good intentions go to die. You pull a frozen container out, you're hungry, and the microwave or a hot water bath looks so tempting. Resist. The same thermal shock physics that governs freezing applies in reverse: a frozen glass container plunged into sudden heat experiences exactly the kind of rapid temperature change that regular glass can't survive — and even quality glass shouldn't be pushed through.

The safest method is refrigerator thawing. Move the container from freezer to fridge and let it warm slowly over hours. This keeps the temperature change gradual and even across the glass. Room-temperature thawing on the counter is the faster alternative — still gradual enough for freezer-safe glass, just keep it out of direct sunlight or heat sources.

What to avoid is anything abrupt. No hot water baths, no direct heat, no immediate transfer from freezer to oven. Glassware guidance is consistent on this point: gradual temperature transitions are the rule, in both directions. If you need to reheat the food itself, transferring it out of the still-cold glass into a separate vessel is the cautious play.

A couple of scope notes so you know what this guide covers: it's about freezer storage only — not canning or preserving — and it doesn't compare glass against plastic or silicone. I'm also not recommending specific brands; look for the glass type or freezer-safe label, not a logo.

Why Some Glass Survives the Freezer (and Yours Can Too)

Understanding Glass Types: Why Some Withstand the Cold

Tags

Freezer-Safe Glass: A Step-by-Step Safety Checklist

Safe Thawing Techniques for Frozen Glass

Confidently Freezing in Glass: Your Next Steps

Sources

Related articles

The Five Accompaniments That Balance Any Cheese Board — and the Cheeses They Belong Beside

The Science of Charcuterie: How Salt, Drying, and Fermentation Turn Raw Meat Into Preserved Delicacies

Brewing Your First Kombucha: How Time, Temperature, and pH Move Your Tea From Sweet to Tart

Four Artisanal Salts Worth Your Money: Which One to Cook With, and Which to Sprinkle Last