Pyrex is one of the most versatile kitchen materials ever. Containers made from this elite material have been advertised for years to withstand extremes of temperature without harm and remain stable and usable for years.
But even with its sterling reputation, Pyrex still has its limits, some of which could surprise you.
Can you broil in Pyrex?
It is not advisable to put any glass dish under the broiler, even though that glass might be specially reinforced as Pyrex is. It might break, and if it does, it can be a messy and even dangerous thing to have to clean up.
Pyrex can be heated up to a temperature of 450°F. The problem is that when you place it into a broiler, it could be exposed to temperatures as high as 500°F to 550°F, and if it is, it could easily crack and disintegrate.
You are better off using a solid metal pan that can withstand the heat. You can also use a rimmed-edge sheet pan equally well.
What happens when you broil Pyrex?
When you cook with a broiler, you're using a direct flame. You slide the pan in immediately below it, which means the food cooks quickly. It also gives it great texture as well as charring it nicely.
But, although you might use what you think is a strong Pyrex dish or pan, it will not withstand that sort of temperature. It will get damaged, and if it breaks or cracks, you can't risk eating the food in it either.
There might be tiny shards of glass that would damage your insides if you unknowingly digest them. It's not worth the risk.
How hot does a broiler get?
Some broilers only have two settings - on and off. Some also have high and low options. However, there's no point in using the low heat setting because if you do; you're not broiling - you're only roasting.
So, you need to use that high setting, and if you do, it will only take about five minutes to reach between 500°F to 550°F, at which point it's bye-bye Pyrex pan.
The limitations of Pyrex
When Pyrex cookware first went on sale, it quickly became the go-to material for many cooks and homemakers. It was advertised in Good Housekeeping magazine in 1936 as something you could buy and "Now cook in glass on an open flame," to use the exact words of the ad.
Today, we know better - or some of us do. We know that Pyrex does have its limitations. Take a look below.
Pyrex's temperature limit
Pyrex cookware was designed to be able to use for baking. However, it shouldn't be heated to over 425°F. If it is, it could fail. So, if you follow a recipe that calls for cooking at over 425°F, don't use a Pyrex dish - use a strong metal one instead.
The modern process for manufacturing borosilicate Pyrex glassware has changed since Corning Glass Works first began fabricating Pyrex for cooking on stovetops.
The fact of the matter is that if modern Pyrex is exposed to a direct heat source such as a broiler, it is likely to crack.
According to Cooksillustrated, cracking is most likely when a cold Pyrex dish or container is heated too rapidly. Yes, Pyrex is better than most types of glass at dealing with temperature extremes; however, it is still not recommended to expose it too fast to changes in temperature.
Why did my Pyrex dish explode?
If any form of glassware, including Pyrex, is exposed to quick temperature changes, it can result in something known as "thermal shock," which could cause the glass to shatter.
When glass is heated or cooled, it expands or contracts accordingly. It can cause cracks to form and even result in the glass exploding. When you transfer a cold glass container into a hot oven or conversely transfer a hot dish into a cold environment, different glass areas expand or contract at different rates.
The variety of glass that is used in making a dish dictates its ability to deal with thermal shock. The first Pyrex oven-safe cookware made in the 1930s was made using a material known as borosilicate glass.
The process for producing uses Boron. It helps to make glass super resistant to extremes of temperature. In terms of its introduction into glass cookware manufacture, it was introduced so that the glassware carrying it could withstand the hottest temperatures of the standard oven.
So, in those early days, borosilicate glass Pyrex wasn't something that shattered in ovens.
However, in the modern-day, Pyrex dishes are made using tempered soda-lime glass. Tempering soda-lime glass increases its durability and thermal shock endurance.
It's much less prone to cracking than ordinary soda-lime glass (which was used in the manufacture of windowpanes), but it is not as strong and durable as borosilicate glass. It's what created the Pyrex glass controversy, which doesn't want to lie down and die.
Few tips that help to avoid exploding your Pyrex cookware.
Rather than putting your Pyrex cookware into an oven while heating up, wait until the oven has reached temperature. This way, you can avoid exposing your cookware to the extremely high temperatures that some ovens generate during the first few minutes of heating up.
Don't add cold liquid during baking. The rapid introduction of something cold can result in dish shattering.
To avoid losing any liquid during the cooking process, you can add a small amount of liquid before baking which will help stop cold liquid from seeping out of the food and dripping down to the bottom of the Pyrex cookware.
Glass and sudden changes in temperature
Rapid temperature changes can have devastating effects on glass, including Pyrex glass. Many tales are floating around regarding Pyrex cookware exploding or shattering. In most cases, these stories are related to sudden changes in temperature, which compromise the integrity of the glass.
While some temperature-changing situations are openly apparent, like taking a Pyrex cookware dish from the fridge and transferring it immediately into a hot oven, others are a little less obvious.
One less obvious scenario is taking a Pyrex cooking dish from a hot oven and setting it on a wet kitchen worktop. The thin layer of water on the worktop is cold and can induce the sort of thermal shock that can destroy Pyrex.
What the manufacturers do and don't say about Pyrex
The original manufacturers of Pyrex, Corning Glass (now made and marketed by Corelle Brands), have never specifically warned about transferring a cold glass onto a hot surface.
However, they do make a statement about avoiding sudden changes in temperature and warn about not adding liquid to glassware when it's hot.
They also advise against placing hot glassware on cool or wet surfaces, on worktops, metal surfaces, or sinks. Hence, further, advise against using a wet cloth to handle hot glassware.
How to prevent Pyrex from exploding
Here are some additional tips about things you shouldn't do when cooking with Pyrex equipment.
1 Use trivets or hot pads on which to stand hot Pyrex cookware
Don't position hot Pyrex cookware directly on top of your stove's metal eyes. The eyes themselves are heat resistant. However, positioning hot Pyrex cookware on a cool metal substrate can cause the Pyrex to shatter.
What you ought to do is to first place a trivet or hot pad or even a folded dry dish towel onto the stovetop or work surface, onto which you can then transfer the hot Pyrex dish. A wooden cutting board is another alternative.
2 Pre-wet a Pyrex dish before cooking dry food
When you bake dry food in a Pyrex dish, it's best to first add a small amount of water to the bottom of the dish. The reason for doing this is that as some dry foods cook, they may release water that would otherwise reach the Pyrex dish's surface.
If the released water is still cold and it comes into contact with the dish's heated surface, it could cause it to shatter.
However, the small amount of water you add to the Pyrex dish before cooking warms up in the oven and creates a buffer between the surface of the Pyrex and any cool liquid that escapes from the food being cooked.
3 Ensure you use dry oven mitts
Only ever use dry mitts or cloths. Wet mitts or cloths tend to conduct heat quite readily, so you can easily burn your hands. You will, of course, use oven mitts or something similar when handling hot Pyrex cookware, but please ensure that the mitts are completely dry.
4 Avoid especially high heat cooking
Although Pyrex has good tolerance toward heat, it's not inexhaustible. For example, the heat generated in a broiler (500°F to 550°F) is too much for some Pyrex cookware. Before taking any risks, please read the cookware manufacturer's instructions and recommendations.
5 Allow Sufficient Cooling Time
This is particularly important if you're going to be dishing up the food you cooked in Pyrex cookware using a metal spoon. Make sure the spoon is at room temperature. If it's too cold and it comes into contact with the Pyrex, it might cause it to crack.
The other thing to be aware of is that glass cookware tends to hold heat well. It's why it's so useful for cooking. But because it holds the heat well, it's important to allow sufficient cooling time before you start serving.
What to do if your Pyrex does shatter?
Once you've stopped cussing and crying, you need to clear up the mess.
Always make sure your hands are protected in case there are any sharp glass fragments around. Don't try and rescue the food. Throw it in the bin.
Mini pieces of Pyrex can easily become lodged in the food, and they're almost invisible to the naked eye, so don't risk trying to serve the food.
Also, when glass shatters, pieces fly everywhere. You'll be surprised at how far they can travel, so carefully sweep the entire area to rid it of any shards.
How to clean up small pieces of shattered glass in the oven?
You can use several things to pick up tiny pieces of shattered glass or Pyrex from also services, including the inside of your oven.
- Slices of soft bread- Tiny pieces of glass will stick nicely into a soft slice of bread. A slice of bread also has the advantage of presenting a wide surface with which you can cover a reasonable area of a worktop, your floor, or the inside of your oven.
- Raw potato (halved)- Another food item with which you can pick up tiny pieces of broken glass is raw potato. Simply halve the potato, then press the exposed surface area of the halves onto the substrate from which you want to collect the glass.
- Adhesive tape-Adhesive tapes, like duct or packing tape, works really well. But ensure you use a nice wide tape and don't press it down too hard so you can avoid cutting yourself.
- Folded damp paper kitchen towel- Fold a sheet or sheets of paper kitchen towel several times, then wet it so it becomes nice and damp. Then, you can gently press the folded pad down onto the substrate to collect glass shards. But please make sure that you fold the paper enough times so the small pieces of glass can't cut through and don't press down too hard.
Will Pyrex cookware explode in your microwave?
Pyrex cookware is normally quite safe in microwaves providing you observe the following conditions.
- Don't transfer a cold Pyrex dish straight from the fridge into a high-temperature microwave. If you do, as the microwave operates, it may cause areas of the glass to expand at different rates.
- It could lead to the cookware shattering. Since the production method changed from borosilicate glass to tempered lime glass, Pyrex doesn't withstand as much stress as it once did.
- Before transferring a cold Pyrex piece of cookware into a high-heat oven, pour a little warm water into the dish or pan.
When to use Pyrex and metal cookware
Next time you're baking or roasting, don't just take the first piece of cookware that comes to hand. Always remember that some cookware materials are better than others in certain situations.
When you're baking a batch of cookies, you'll probably instinctively prepare a metal baking sheet. However, when you're cooking a casserole or a lasagna, you're more likely to reach for a piece of Pyrex cookware.
It's simply what many of us do but is not necessarily advisable.
When to use glass bakeware
To put what I said earlier in context, glass is actually a relatively poor heat conductor, but it distributes heat evenly across its entirety. The result of this is that while glass cookware doesn't heat up particularly quickly, once it is hot, it stays that way for much longer when it's taken out of the oven or off the stovetop.
It's a great advantage if you're serving casserole-type dishes that you want to stay warmer longer when you take them out of the oven and transfer them to the tabletop. The same applies to ceramic dishes.
But when you're broiling food, glass cookware isn't recommended because it might shatter. The fact is that glass cookware is not best used with direct high-heat cooking sources, such as stovetops.
If you are tempted, make sure to read the cookware manufacturer's instructions.
For example, if you're roasting a joint and want to take advantage of the residue left in the tray to make gravy on your stovetop. Use a metal roasting pan rather than one made from Pyrex.
- Pyrex cookware is great for cooking braised or casseroled dishes that you want to serve directly from your tabletop.
- Pyrex cookware is a no-no when broiling food or transferring it directly from the oven to your stovetop.
Why and when to use metal bakeware
In particular, metal cookware and aluminum are fantastic at conducting heat. The only problem is that it also loses heat pretty quickly. But it's great for cooking food that you want to heat up quickly and that you like brown, like roasted potato wedges.
Next time you're buying a metal baking sheet, go for one made from a thicker grade of aluminum because it will be great for baking cookies without burning them.
Don't use metal cookware when cooking reactive foods with an acidic base. If you do, the acid will cause a reaction with the metal resulting in the pan discoloring. Sometimes, it will add a slightly metallic flavor to the food, which you are better off without.
- Metal bakeware is great for roasting and browning.
- Avoid using metal bakeware with reactive foods like fruit or cooking dishes that you want to stay warm for serving.
Cookware you should not put under your broiler
Regardless of whether it's a gas flame or electric coil, it's not just Pyrex cookware that shouldn't be exposed to the heat of a broiler.
1 Nonstick coating cookware
Ordinarily, nonstick cookware is not designed to be exposed to high-temperature environments such as broilers or direct flame.
Check the cookware first. If it says that it is broiler-safe or okay with temperatures of up to 550°F, rather than using nonstick cookware, it's best to use stainless steel or seasoned cast-iron.
2 Skillets with protected grips or handles
Pans with handles covered with some material to stop you from burning your hands when you take the pans off the heat are unsuitable for putting under a broiler flame. This is also applicable to plastic or wooden handles.
Don't make the mistake of thinking that the detachable silicone handles that you can buy for cast-iron skillets are broiler-safe.
They are only designed to stand up to temperatures of up to 450°F. So, again, these are not suitable for going beneath broiler flames.
3 Avoid lining pans with parchment paper if they're going under a broiler
You might be inclined to line your baking sheet or skillet with parchment paper before putting it under the broiler flame to prevent any fat, grease, or marinade from being baked onto the pan's bottom. Don't do it.
Although parchment paper is heat resistant, it can still catch fire. If you must line your baking sheet or skillet with anything, line it with aluminum foil.
Foods you should not broiler cook
Some foods are great for cooking in a broiler; some are not. Here's a list of foods to avoid broiler cooking:
- Steak straight from the fridge - It's not a good idea to broiler kook cold meat straight from the fridge. Although the outer will brown nice and quickly while the center of the steak will still be very-rare. So unless you like bloody steaks, it's not a good idea.
- Large joints of meat or whole chickens - Just like steaks, large joints or whole chickens will get charred on the outside while the inners will still be uncooked.
- Be careful with cheese - Cheese will go from being beautifully golden and bubbly to being blackened and blistered in seconds. If you want to use this method of heating cheese, you should leave your broiler door open and watch what's happening every second.
- Fresh herbs and spices and greens - These will all char and maybe even catch fire very quickly, so again, as above, you need to leave the broiler door open and be continuously watchful.
- Oil sodden foods - I once made the mistake of cooking confit chicken thighs, which you probably know are slow, deep-fat-fried at low temperature, and full of grease, into my broiler. They caught fire, and I thought I was gonna have to call the Fire Brigade. If you put any greasy foods under a broiler flame, make sure there's a good six inches between the flame and the food, and again, keep an eye on proceedings.
A Summary of mistakes you could be making with your broiler
Although broiler cooking is a great way of cooking food from a heat source above, there are a lot of mistakes that many people make.
So, here are some things to be mindful of.
1 Allow sufficient space between the food and the flame
I already mentioned this above under "oil sodden food." But it's a common mistake, so it's well worth mentioning again. Don't place the food too close to the flame, especially if you're using smaller pans or dishes that are not very deep.
I mentioned a six-inch gap with something like confit chicken thighs. However, these are especially greasy. Ordinarily, somewhere between three to five inches between food and flame should be okay.
2 Don't forget to preheat your broiler.
Okay, it's not a grill, but you still ought to preheat your broiler for a few minutes before you start cooking so that it's nice and hot and ready to go.
3 Getting the temperature setting right
The settings on broilers are pretty simple. Broilers usually have only on, off, high and low controls. They're not like those on an aircraft cockpit, thank goodness.
The high is meant for food that needs more time to cook, like many vegetables. Foods that cook more quickly can be broiled under the low heat setting.
4 Only use broiler-safe cookware
As already mentioned, Pyrex and glass cookware are not really suitable for broilers. You will be better off using rimmed sheet pans or sturdy metal pans. They are much more suitable.
5 Positioning the food correctly
As with any form of cooking, you need to position your food evenly to get cooked evenly. You don't want to be serving a mixture of overcooked, well-cooked, and undercooked food, which will happen if you don't space it out correctly.
6 Being mindful of the speed of broiler cooking
Broilers cook fast - even those located in your oven. The majority of foods will, on average, be properly cooked after five or ten minutes.
7 Don't overheat your oven.
If your broiler is located in your oven and your oven overheats, it can make your broiler shut itself down. To avoid this happening, it's a good idea to leave your oven door slightly open when broiling.
Pyrex cookware and broilers don't mix. Because it's not designed to stand so much heat, Pyrex cookware can easily shatter under the heat of a broiler.
If that should happen, it not only destroys the pan but also renders the food inedible because it might contain minuscule shards of glass that could cause you serious internal damage.