Provided you heat Pyrex at a reasonable rate it can withstand temperatures much higher than boiling water. However if you thermally shock Pyrex it may break (by taking a Pyrex Bowl out of the freezer and plunging it into boiling water for instance).
The effects of thermal shock are great and can cause the glass to break. Even pyrex (like Pyrex) can break when improperly poured boiling water. To prevent the glass from breaking when exposed to boiling water, sudden and drastic temperature changes should be avoided.
Yes, Pyrex would be safe as a double boiler. It doesn't take fast changes in temperatures well. Keep water in it or don't add water if it runs dry but it is still hot.
It is a tempered borosilicate glass, of superior quality and high resistance to thermal and mechanical shock. It is perfectly suited to extreme temperatures, from -40° to 300°, and has great resistance to thermal shock of up to 220°. All Pyrex® glass products are safe to use in the oven, freezer and vice versa.
If you have a special application that REQUIRES boiling water (or water that's much hotter than the glass's normal temperature) then you want something that is "lab rated", or "borosilicate glass" (like they used to make Pyrex out of, before they started using cheap glass).
It is possible for a glass jar to break when exposed to boiling water. The primary culprit behind glass breakage in boiling water is thermal shock. This phenomenon occurs when a glass jar experiences a sudden temperature change, causing uneven expansion within its structure.
Keep in mind that while mason jars can handle boiling water, it's generally recommended to use them for liquids close to boiling or even slightly cooler. If the hot liquid has been simmering for a long time, letting it cool slightly before transferring it to the jar is a safe practice.
Pyrex is oven-safe up to 425 degrees. However, direct contact with heating elements can cause the glass to shatter or break. Pyrex is not oven-safe when used under the broiler or in a toaster oven.
PYREX lab glassware made with borosilicate can withstand harsh, corrosive chemicals, handle extremely low and high temperatures, and it can survive rapid temperature changes without sustaining damage.
Be sure to allow hot glassware to cool as provided above before washing, refrigerating or freezing. Oven must be preheated before inserting glassware. DO NOT use on or under a flame or other direct heat source, including on a stove top, under a broiler, on a grill or in a toaster oven.
If the logo is in upper case lettering, PYREX, it's most likely made of borosilicate, and thus safer. The lowercase lettering is most likely made of soda-lime glass, so take extra care after any high-heat cooking.
Mixing bowls of glass or stainless steel are heat-resistant and work best for double boilers. 2. Prevent the bottom of the bowl from touching the hot water. The bowl will get too hot if it touches the water, which could negatively affect your ingredients.
Don't use Pyrex on the stovetop: This heat is too extreme for these glass dishes.
"Avoid sudden temperature changes to glassware," the Pryex website reads. "DO NOT add liquid to hot glassware; place hot glassware on a wet or cool surface, directly on countertop or metal surface, or in sink; or handle hot glassware with wet cloth." (The all-caps emphasis is theirs.)
A: Yes. But as a pouring device it is useless.
Glass cookware can shatter or crack under the broiler's high heat, and that even includes heavy-duty Pyrex dishes. If you plan to place your casserole under the broiler to achieve a crispy top, skip the glass and opt for enameled cast iron, ceramic, or porcelain casserole dishes instead.
The differences between Pyrex-branded glass products has also led to controversy regarding safety issues—in 2008, the U.S. Consumer Product Safety Commission reported it had received 66 complaints by users reporting that their Pyrex glassware had shattered over the prior ten years yet concluded that Pyrex glass ...
Check to see if there is a marked "Oven-Safe" symbol underneath the piece. Glass bowls made of borosilicate or tempered glass and marked as oven-safe can go in the oven and withstand high temperatures. Those made of non-tempered glass may not be suitable with heat resistance and withstanding temperature changes.
A: Yes. Make sure that the Pyrex bowl you will use is bigger than the pot you're boiling the water in, so the steam dosn't escape and get in the food (especially chocolate).
Avoid sudden changes in temperature.
Don't pour boiling liquids into glass measuring cups, and let hot Pyrex dishes cool before you run water over them.
In conclusion, the decision by Pyrex to transition from borosilicate to soda-lime glass was driven by cost, durability, and manufacturing efficiencies.
The USDA Food Safety and Inspection Service has deemed Pyrex as microwave safe. There are some things you need to know though! Pyrex is made of either borosilicate or soda lime glass and is heat resistant up to 425 degrees Fahrenheit, making it a good option for microwaving.
Temperature Difference (Thermal Shock)
Severity: The greater the temperature difference between the hot water and the glass, the greater the risk of the glass breaking. For example, pouring boiling water into a cold glass is riskier than pouring warm water.
The two-piece lid system (flats and screw bands) is the best option for home canners. They are easy to use, seal reliably, and easy to tell if the jars sealed. When researched guidelines are followed, the two-piece lid system safely replaces the vacuum system used for commercially canned foods.
Heat Resistance Test
Remove the heat and check if the glass surface cracked — if not, it's likely tempered. Tempered glass can withstand much higher temperatures due to the strengthening it receives during manufacturing.