When a Pyrex bowl is heated or cooled rapidly, different parts of the bowl expand or contract by different amounts, causing stress. If the stress is too extreme, the bowl's structure will fail, causing a spectacular shattering effect.
Pyrex is meant to be able to withstand higher temperatures. But everything has its limitations. Pyrex can be used safely inside an oven that is less than 450 degrees F. Whether or not it's inside a conventional oven or a convection oven, this glassware will be safe to use so long as that temperature isn't exceeded.
Pyrex is not resistant to thermal shock, therefore, there are instances where Pyrex glassware can explode when it is moved from a hot environment to a cold one and vice versa. In short, avoid exposing your Pyrex to extreme temperature changes at all times.
You can use a Pyrex oven-safe dish in a 400-degree oven. Before the first Pyrex pie plate was manufactured in 1916, home cooks didn't have access to glass bakeware that withstood both high and low temperatures without breaking.
Why you can't put cold Pyrex in the oven. When Pyrex was first created back in 1908, it was made with a special glass (called borosilicate glass) that was thermal shock-resistant. That means that dramatic changes in temperature, like when putting a cold dish into a hot oven, were no match for the sturdy glass.
Is Pyrex glassware susceptible to shattering? Shattering is relatively rare, but it can happen when glassware is exposed to sudden temperature changes (known as thermal shock), extremely high heat (over 425 degrees), or direct heat.
"Could have been an impurity in the glass, could have been a disruption in the production cycle … Somewhere in the cooling and the contraction part," Kikkert said while discussing Hill's case. Mistakes in the crafting of a product can introduce strain that may cause it to shatter, sometimes forcefully, at any time.
It's best to put the dish on a dry dish towel or a metal cooling rack to cool. Damp towels or surfaces can also cause the hot glass to shatter. Don't use tempered-glass bakeware on the stovetop, under the broiler, in a toaster oven, or on a grill.
Although Pyrex glass mixing bowls are designed for mixing and storing, they are safe to use in a preheated oven up to 425°F. They are also microwave safe.
Pyrex cookware is meant to withstand baking, but it cannot be trusted for use over 425 degrees. This means that for recipes requiring higher temps you should use metal pans.
Products with the name 'pyrex' (all lowercase) are made by a company called World Kitchen and are made out of clear tempered high-thermal-expansion soda-lime glass, which has a lower thermal shock resistance, making them susceptible to explosions in the microwave or oven.
While chances that you will get acute lead poisoning from using vintage Pyrex are minimal, do not underestimate the damage exposure to tiny amounts of lead can do over time. As lead accumulates in the body, it can cause irreversible damage.
Do not put glass under the broiler, even if it's strong and enforced, like Pyrex. It could break and that is just a mess you do not want to deal with. Instead, use a sturdy metal pan that can stand the heat.
What Make Glass Shatter? When glass goes rapidly from something cold to hot (like a freezer to an oven) or vice versa, it can experience “thermal shock.” Different sections of a piece of bakeware can expand or contract differently and cause it to lose its structure, resulting in a shattering effect.
Even being oven safe won't protect a glass that is on the verge of breakage, and it will likely shatter once exposed to high heat. Along with this, many glass dishes labeled as oven safe still have a temperature limit.
Some glass containers are oven-safe while others are not. Most oven-safe containers have a symbol located on the bottom. Tempered glass is always safe for oven use; however, non-tempered glass should never be placed in an oven. Make sure to look for the symbol on your container along with temperature guidelines.
The most common causes are: Internal defects within the glass such as nickel sulfide inclusions. Minor damage during installation such as nicked or chipped edges later developing into larger breaks normally radiating from point of defect.
This phenomenon is named a spontaneous glass breakage, and it occurs only in Tempered glass, that is suddenly shattered, during it's life span and even years after the glass is already installed in the frame, and seemingly without reason.
Sturdy metal pans, or a simple rimmed sheet pan, are optimal when cooking with a broiler. If you use something else (like a glass pan), it could crack or break under the broiler's heat. Our Test Kitchen's favorite sheet pan is always a good bet.
Most ovens feature a straightforward on or off setting for the broiler, but if your oven does not, set it to high heat, (around 500º Fahrenheit), but leave the oven door a crack open so the oven does not overheat and turn itself off.
Unless your nonstick cookware or bakeware explicitly says "broiler safe" or "safe up to 550°F," your best bet is to choose all-metal pans such as stainless steel or seasoned cast iron.
Best in Glass: Pyrex Basic Dishes
Glass is a naturally non-toxic cookware material and the baking dishes are also non-porous, so odors and stains won't seep into them as you cook your food. Pyrex cookware is dishwasher-safe and safe to use in the microwave, oven, fridge, and freezer.
A: Pyrex is suitable for use from -192°C to +500°C. This makes it an ideal choice for lab glassware which will be directly heated. Pyrex is borosilicate glass which makes it highly temperature resistant. Soda-Lime glass is less suitable for direct heating, so choose Pyrex where possible if you will be applying heat.