Don't pour cold water into a hot pan or put it under the broiler. Don't drop it, don't put it on a hot sheet pan etc. Should be just as safe as anything else like casserole dish.
Don't preheat the bakeware in the oven. Always preheat the oven first before placing the bakeware inside it. According to Pyrex's safety and usage instructions, “While the glass is designed for temperatures typically used in baking, it can break when exposed to the direct heat element while the oven is preheating.”
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.
Glass cookware can sometimes explode due to extreme temperature changes, so make sure you warm up the cookware slowly before use and never put a cold lid on a hot pot.
Pyrex eventually switched to tempered glass most likely because boron is toxic and expensive to dispose of. Although tempered glass can better withstand thermal shock than regular soda-lime glass can, it's not as resilient as borosilicate. This is what causes the shattering reaction people are talking about.
Pyrex (or any other glass, for that matter, could shatter. There is a simple solution to this. Simply rinse the dish with hot but not boiling water first. You should do the same thing with glass thermos containers.
Place the pan on top of an unheated metal baking sheet before sliding it into the oven. This helps prevent abrupt temperature spikes that could damage the glass. This little trick smooths out any sudden spikes in temperature, keeping your glassware safe from shattering.
"Pyrex was extremely popular during those years as people could add fun and function to their kitchen and dining spaces," Wright notes. The glass could withstand extreme temperature changes without shattering, which added to its practicality and made it ideal for baking and cooking, she adds.
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.
Pyrex is oven-safe up to 425 degrees. However, direct contact with heating elements can cause the glass to shatter or break.
This change was justified by stating that soda–lime glass has higher mechanical strength than borosilicate—making it more resistant to physical damage when dropped, which is believed to be the most common cause of breakage in glass bakeware. The glass is also cheaper to produce and more environmentally friendly.
Because borosilicate is the most durable when it comes to withstanding temperature changes, it is generally considered the safest choice for glass bakeware.
Baking glassware such as Pyrex dishes in usable condition should be donated to local thrift stores or otherwise reused. If unusable they should be thrown away in the trash. They should not be added to curbside recycling. They are made of a different material than glass bottles and jars.
Thermal Shock
Changes in temperature cause glass to expand and contract, and when this is done at different severities across the glass with the edges and centres changing in opposite directions, the pane is put under stress which can cause it to break.
Decorative patterns are also key to determining the glassware's value. Lucky in Love, a sweet pink and green design, is prized for its rarity and promotional production. Wright notes that Amish Butterprint, Pink Gooseberry, Snowflake Blue, Crazy Daisy and Friendship are also considered valuable in the Pyrex community.
pyrex: Lowercase indication of containers that should not be heated in the oven or microwave. These are most likely made of soda-lime glass. PYREX: Uppercase label on cookware that is made of borosilicate glass and can be heated in a microwave or oven.
Patterned Pyrex—such as the 1956 Pink Daisy or the 1983 Colonial Mist colorways—tend to be valuable as a collector's item. Other popular patterns include the 1957 Butterprint, which features an Amish couple and their crops, and has been valued at a few hundred dollars.
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.
Protect glass from impacts.
Place barriers like plants, sculptures or furniture in front of large panes of glass when possible. This helps prevent impacts from trolleys, carts or other equipment that could shatter or weaken the glass over time.
Can I Line Any Baking Pan with Foil? Yes!
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.
When using Pyrex or any glass bakeware or cookware, you should avoid extreme temperature changes—very cold dishes shouldn't be placed in a hot oven, and vice versa. Sudden changes in temperature may cause the dishes to shatter or break.
Traditionally, melting chocolate is done over a bain-marie, aka a double boiler. A heat-proof glass bowl, such as sturdy Pyrex, is set over a deep pot filled with about an inch of water. Chocolate chunks are added and slowly melt, thanks to the heat of the simmering water beneath it.