Is It Safe to Put a Glass Baking Dish Under the Broiler or on the Stove?

Clear Answer

No. Pyrex and Anchor Hocking, the two biggest glass bakeware makers in the US, both say their dishes must not go under a broiler or on a stovetop burner, because either one can crack or shatter the dish, sometimes violently. Glass belongs only in the even, surrounding heat of a fully preheated oven.

The reason is thermal shock, and once you understand how it works, the other rules on the label (preheat first, don't add cold liquid to a hot dish, never set it on a wet counter) start to make sense too.

What the manufacturers say

The warnings are printed in the care instructions, and they are blunt.

Pyrex's use-and-care warnings say: "DO NOT use on or under a flame or other direct heat source, including on a stovetop, under a broiler, on a grill." Its FAQ repeats that glass "is not to be used with any direct heat source such as on the stovetop or under the broiler," and it adds toaster ovens to the list of places not to use it.

Anchor Hocking's instruction sheet uses nearly the same words: "Not for use on or under a flame or other direct heat source, including on a stovetop, under a broiler." It also caps oven use at 425°F, in a preheated conventional or convection oven.

If your dish is a different brand, find its care sheet before you assume anything. Other kitchen tools come down to the label too, so read the care sheet first. Most glass bakeware sold in the US follows these same limits.

Why does glass crack under direct heat?

Glass expands when it heats and shrinks when it cools. That alone isn't a problem. The trouble starts when one part of the dish heats much faster than the part right next to it.

Under a broiler, the top rim and any exposed glass are blasted with radiant heat from a few inches away, while the bottom and the parts covered by food stay much cooler. On a burner, it's the reverse: a ring of glass directly over the flame or coil gets very hot while the sides stay near room temperature. The hot zone tries to expand, the cool zone holds it back, and that tug of war builds stress inside the glass.

Glass is strong when you squeeze it but weak when you stretch it. When the stress in the cooler, stretched area passes what the glass can handle, a crack starts, usually at a tiny scratch or chip, and runs through the dish in an instant. That is thermal shock, caused by a big temperature difference across one piece of glass.

An oven avoids this because hot air surrounds the whole dish and heats it gradually and fairly evenly. That's why the label says preheat first. Sliding a dish into an oven that's still heating means it sits near glowing elements that are cycling at full blast, which is a bit like a mild broiler. It's also why an oven that runs hot is worth checking.

Does it matter if your dish is old Pyrex or new pyrex?

It makes a little difference, but not enough to change the answer.

Glass bakeware comes in two main types:

• Borosilicate glass. This is what Corning originally used for Pyrex, starting in 1915. It expands very little when heated. Chemistry references put its thermal expansion around 3 × 10⁻⁶ per degree, roughly a third of ordinary glass, which makes it much more forgiving of temperature swings.
• Tempered soda-lime glass. After Corning sold the brand in 1998, US-made pyrex switched to tempered soda-lime glass, according to Iowa State University Extension. Anchor Hocking also uses tempered soda-lime. Soda-lime glass expands about three times as much (around 9 × 10⁻⁶ per degree), so it handles sudden temperature changes less well. The tempering makes it better at surviving drops and bumps.

Iowa State's extension notes a quick way to tell them apart in the US: older Corning dishes are stamped with all-capital "PYREX," while the newer soda-lime dishes use lowercase "pyrex." Pyrex itself says borosilicate is "slightly more resistant to extreme thermal changes than soda lime," and that both types are safe at any temperature a recipe calls for in an oven.

Even borosilicate isn't approved for the broiler or burner by the people who make it. Lower expansion gives a margin of safety against accidents, and the rules still apply. A vintage dish may also carry decades of scratches, and scratches are exactly where cracks start.

What happens when a glass dish fails?

Tempered glass doesn't just crack in two like a dropped plate. Tempering locks tension into the glass, so when it finally lets go, it can burst into many pieces at once and throw them across the counter. People describe it as the dish "exploding," and that isn't much of an exaggeration.

Consumer Reports looked into this in 2010. In its testing, a hot soda-lime dish set on a wet granite countertop shattered almost immediately, and the magazine asked the Consumer Product Safety Commission to investigate. The scenario is a textbook case of thermal shock: a hot bottom suddenly cooled in one spot by cold, wet stone.

If a dish breaks mid-cook, throw out the food. Tiny glass fragments are hard to see in a casserole or a pan sauce, and it isn't worth the risk.

Seven habits that crack a glass dish

Most broken dishes don't come from broilers. They come from small temperature mistakes that seem harmless. Here are the ones both manufacturers and Consumer Reports call out:

1. Putting the dish in before the oven is fully preheated. Wait for the preheat signal, and give the oven a few extra minutes if yours tends to overshoot.
2. Going straight from freezer to hot oven. Pyrex says not to do this. Thaw the dish in the fridge first, or bake the food in a different pan.
3. Adding liquid to a hot dish. Splashing broth or water into a hot roasting dish chills one area fast. Both brands say not to do it.
4. Roasting dry. Meat and vegetables release juices that hit the hot glass. Pyrex and Anchor Hocking both say to add enough liquid to cover the bottom of the dish before cooking foods that will release liquid.
5. Setting a hot dish on a cold or wet surface. That means sinks, wet towels, stone counters, and metal stovetop grates. Use a dry towel, cork or wood trivet, potholder, or a dry wooden cutting board.
6. Washing it while hot. Let it cool before it goes in the sink, the fridge, or the freezer.
7. Using a chipped or scratched dish. Damage weakens the glass. Consumer Reports recommends throwing out dishes with chips, cracks, or deep scratches.

Can you finish a casserole with a quick broil if you watch it closely?

This is the most common temptation: the mac and cheese is cooked, and you just want the top bubbly and brown for two minutes. Watching closely doesn't change the physics. The rim of the dish is still sitting inches from the element, and short bursts of intense heat are exactly what causes uneven expansion.

You have a few better options:

• Crank the oven instead. Move the dish to the upper third of the oven and raise the temperature for the last 10 to 15 minutes, staying within your dish's limit (425°F for Anchor Hocking). You won't get a true broiler char, but you'll get good browning.
• Bake in a broiler-safe dish from the start. Enameled cast iron, plain cast iron, metal pans, and ceramic or porcelain dishes labeled broiler-safe can all handle it. Check the label, since not every ceramic dish is rated for the broiler.
• Transfer before broiling. For something like a gratin, spoon it into a broiler-safe dish for the final step.
• Use a kitchen torch for small jobs like browning a cheese top or meringue.

What about warming something on the stove in a glass dish?

Same answer: no. A burner heats a small patch of the bottom intensely while the rest stays cool, which is the worst kind of uneven heating. Electric coils, glass cooktops, gas flames, and induction (which won't work with glass anyway) are all off the table.

It also isn't safe to use a glass dish as a lid or to rest one on a hot burner while you clear space. If you need to reheat leftovers that are in a glass dish, use a preheated oven or the microwave (following the brand's microwave instructions), or move the food to a pot or skillet.

Glass that is made for stovetop use does exist, but it is a specialty product with its own markings and instructions. If the box and the bottom of the dish don't say stovetop-safe, treat it as oven-only.

Quick reference before you reach for the glass dish

Glass bakeware is great for even, gentle baking, and it lets you see the bottom crust. Keep it in a fully preheated oven, keep it away from sudden temperature swings, and reach for metal or broiler-safe ceramic whenever the recipe says broil or stovetop.

How does careful glass bakeware handling look?

Thermal shock is invisible until the glass fails, so the safe habits are best learned by watching how a dish is moved and set down. Judi in the Kitchen cooks with glass bakeware.

Glass 101 - Minimize the Risk of Breaking Glass Bakeware
By Judi in the Kitchen on YouTube. Their method may vary a little from ours. Watch on YouTube