Look on the bottom of the dish. It should indicate whether or not it is oven-safe: See, on the bottom right, a little oven.
The next time you go to cook dinner in a Pyrex pan, take a look at the labeling. Cookware with lowercase logos are usually made of soda-lime glass and should not be heated up in the oven or microwave to minimize risk of them breaking.
Brittle materials like glass are much more vulnerable to thermal shock, because they break when their molecules quickly expand under heat or contract under cold.
Borosilicate glass is durable and able to withstand temperature changes, so it can go from a 0°F (-18°C) freezer to a pre-heated 450°F (232°C) oven without shattering. However, like all glass, it's still breakable, and should always be handled with care.
Pyrex bowls (both old and new) are safe to use in your oven -- and microwave -- as long as you avoid dramatic, sudden temperature changes. Stovetop (either gas or electric) use is not safe.
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.
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.
Flip over the glass pan to look for "oven-safe" markings imprinted on the bottom. If the manufacturer says a pan is good for baking and broiling, you can trust it. For sturdier options, turn to Pyrex or borosilicate glass. Pyrex holds up to around 220 degrees Celsius, suitable for most recipes.
CAN I PUT MY MASON JAR IN AN OVEN? No. Keep your Mason jars out of the oven. Kacey Christian from the National Center for Home Food Preservation says that oven processing times are inaccurate, the temperature fluctuates too much, the oven's dry heat is unsafe, and the jars are much more likely to shatter.
Going immediately from cold to hot or vice versa can cause your dish to crack or even shatter, so if you are planning to bake or reheat food in a Pyrex dish, it is very important that you allow the dish to come to room temperature before you put it in the oven.
Modern Pyrex Isn't the Same as Vintage Pyrex
This change is worth mentioning because borosilicate glass was made to withstand large and sudden temperature swings (or thermal shock) better than many other glass varieties.
I contacted Pyrex to ask if there's an easy way to tell what material your Pyrex dish is made from, and the company had a simple answer: Look at the logo. If it's all caps “PYREX,” it's vintage, made of borosilicate. If it's lower case “pyrex,” it's new, and it's soda lime.
How can you tell if a piece is real vintage Pyrex? The secret is simple—check the logo. If the brand name is in all capital letters, it's vintage Pyrex. If it's all lowercase, it's modern.
And another word on preheating: Pyrex recommends only placing their bakeware in an oven that's already heated. These dishes are designed for the heat of the oven, of course, but the company explains that pans “can break when exposed to the direct heat element while the oven is preheating.”
Both trademarks were historically used interchangeably in the marketing of kitchenware products made up of both borosilicate and soda-lime glass. However, now Corning has licensed out the use of their PYREX (upper case lettering) and pyrex (lower case lettering) logos to other companies.
Mason jars can tolerate heat up to approximately 392°F (200°C) under gradual heating conditions but are prone to thermal shock with sudden temperature changes. Newer mason jars made from tempered glass are generally microwave-safe, but precautions should be taken to avoid sudden temperature changes.
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.
In order to identify if your plate, pot, cup or bowl is oven safe, you need to look for a special Oven-Safe symbol underneath. Some examples of the types of materials that are oven safe are: Metals such as stainless steel and cast iron. Avoid items with non-metal parts such as wooden or plastic handles.
To know whether or not your glass cookware is oven safe, look on the bottom of the dish for a Pyrex symbol or other notation that the glass is safe to put into the oven. If you cannot find a definitive marking, consult the manufacturer. Pyrex Vs. Anchor Hocking: Are They Different?
According to Billingsley, "Oven-safe pans are usually made of copper, cast iron, stainless steel or even aluminum," says Billingsley. "As far as broiler safe goes, nonstick cookware is not designed for the high temperatures of a broiler. Wood, plastic, or silicone handles are not broiler safe."
If you want to reduce the chances of a shatter-fest, a cooling rack or dry dish towel are the recommended methods. As mentioned, many modern glass cookware options are labeled by the manufacturer as stovetop safe. While that may be true, they're made for even distribution of heat.
Yes, Pyrex glass can be used in an oven, but you just need to take a few precautions. The Pyrex products made since 1998 are manufactured from soda-lime, rather than the original borosilicate glass. The newer version is not nearly as “thermal-resistant” as the older one.
You are correct that glass jars are not oven safe. Depending on what you are looking for, you could bake individual servings in ramekins, small Pyrex containers or even ceramic mugs. If you really love the look of mason jars or want the ability to put a lid on, consider making a mason jar trifle.
There are three basic types of glassware: soda-lime, tempered, and borosilicate. Soda-lime glass is the most common glass type in kitchens, found in cups and jars, and is more susceptible to breaking from extreme temperature changes, and therefore is not a good option for the heat tolerance required of bakeware.