Glassware is a popular kitchen item for serving and storing food, but it can also be quite fragile. If you're in the market for some new glassware or if you're just wondering whether glassware from your grandma's house can be heated safely in the microwave, read on.
Glass can crack or shatter in the high heat of a microwave, which can cut you if you handle it before it cools down. Additionally, some types of glass may become so hot that they could burn your skin or cause an explosion inside your microwave. For example, Pyrex—a brand of insulating glassware used for cooking and baking—will sometimes explode when heated above 1,200 degrees Fahrenheit! This is because the borosilicate glass weakens once exposed to temperatures above its threshold limit (Tg).
If you have a piece of glassware that is marked "microwave safe," it may be safe for microwaving. Microwave-safe glassware is marked with a symbol that looks like a circle with a line through it—usually on the bottom of the piece. This symbol indicates that the item can be heated in a microwave oven; however, some pieces may be labeled "Not for use in microwave" instead. If your dish has these markings, you'll want to find out if your particular brand or style of dish can fit inside your microwave before cooking with it.
While metal is a good conductor of heat, it should be used with caution. Metal vessels or metal decorations can cause sparks — which is dangerous for you and the glassware. It's best to avoid using them in the microwave altogether, but if you must (for example, if you have a tray that won't fit in your microwave), then use them sparingly and carefully as they can cause the glass to break.
You should never put metal in the microwave, even if it's just an earring. Metal can spark when it's placed into the microwave, which is especially dangerous if it happens to be a very hot day outside and you're not paying attention. Sparking metal could start a fire or burn you, so make sure you don't put any kind of metal in your microwave—especially anything that has decorative, ornate designs on it.
You should not put glassware with gold or silver rims in the microwave unless you know that the metal is safe for microwaves. Many metal rims aren't safe for cooking because they can melt, warp, and even burst into flames. Do not use any kind of rimmed glassware—including shot glasses—in your microwave unless it says "microwave safe" on the bottom of the item. If you want to be really cautious about it, check with your manufacturer before using any glassware that's been outfitted with a metal rim.
Sometimes you can't always trust whether glassware will hold up in a microwave. Glassware is not always microwave safe. Glassware can crack or shatter in the microwave, especially when it's old, new, or made of different types of glass.
Glassware that's damaged by thermal shock (like putting hot liquids in cold glasses) can cause fires to start inside your microwave oven and damage the outer wall which could even lead to an explosion! Some metal utensils and bowls may also damage your glassware as they're heated together so they don't fit well together anymore after being taken out of the oven.
In conclusion, we can say that glassware is not generally safe for use in a microwave. However, if you follow the rules and use specific types of glassware, you may be able to heat it safely.