Many people have faced the challenge of cracking or breaking their glass kitchenware after putting them in the oven. Because of this, it is very important to know if glass can be put in the oven.
It can be painful to see your beautiful glass kitchenware break or crack.
In this article, I will look at this issue in detail. I will tell you whether you can put your glass in the oven or not. I will also tell you what type of glass is oven safe and which one is not.
Read on to the end.
Yes, you can put glass in the oven. However, not all types of glass are oven safe.
Too much heat (more than 300°F) will cause your glass to crack and break. A glass you can put in the oven must be hardened to withstand this temperature.
To help you understand this matter better, let me discuss the oven-sage glasses and those that are not.
What Type of Glass Can You Put in the Oven?
The only glass that can withstand the intense temperatures inside an oven is tempered glass.
So, what is tempered glass?
It’s a type of safety glass whose manufacturing process involves controlled thermal treatments to increase its strength.
In its manufacture, the tempered glass dish goes through an intense furnace of over 1,000 degrees Fahrenheit. It’s then quickly cooled through high-pressure air blasts.
Glass made with this process is about four times stronger than ordinary glass. Moreover, the glass can withstand high temperatures.
Here are some features of tempered glass:
- stronger than ordinary glass
- has higher thermal strength
- thicker, making it damage and scratch resistant
- highly durable
Because of the above characteristics, manufacturers use tempered glass to make kitchenware, among other products.
How to Tell If Glass is Tempered
Here are a few guidelines to help you know whether the glass dish you intend to buy is tempered.
It should have smooth edges.
Smooth edges are a distinguishing characteristic of tempered glass.
Glass bakeware goes through intense heating and gradual cooling, which makes it sturdier. In addition, it requires sandblasting.
These processes leave the glass with smooth and even edges. Use your finger to test the smoothness of the glass.
On the contrary, ordinary glass will have rough-to-touch edges.zz
You can see some obvious imperfections
Does this seem strange?
Yes, imperfections are a sign of the intense heating that the glass passed through.
During the tempering process, a glass becomes mendable at its hottest point. As it gets picked using tongs, they may leave some slight imperfections.
So, take time to look for some imperfections before you buy the glass dish. If you discover any, that’s a clear sign that it is tempered glass.
Look for darkened shady lines or spots.
To effectively carry out this test, you will need a polarized glass. View the glass against sunlight and notice the difference.
If you can see dark spots or polarized lines, that’s tempered glass.
These lines emanate from the tempering process when the machine rollers go over the glass.
Look for the “bug.”
Did I say bug?
Yes, but I don’t refer to an insect at all.
A bug here refers to a tiny label sandblasted at the corner of the glass. This label bears the manufacturer’s name and the Consumer Product Safety Commission standards.
If you can identify this label, it will tell you whether the glass is tempered or not.
Important note: This mark will be easily visible if you buy the glass from the manufacturer. However, if you buy it from other outlets, it may not always be visible.
Score a line (the last resort)
If you cannot determine if your glass is tempered using the other methods, consider scoring a line.
Caution: Only use this method if you plan to cut the glass.
On the glass surface, score a line using a window-cutting tool. If the line it creates is flaky and uneven, the glass is tempered.
Borosilicate glass is the other option of a glass that you can put in the microwave oven or toaster oven.
Component-wise, this glass contains boron trioxide, which hardly allows for thermal expansion. Moreover, it has a thermal expansion coefficient of at least 3.2 x 10-6 1/K.
Consequently, this glass will not crack even under extreme temperature changes.
The glass is also durable. As a result, it is the glass of choice for many wineries, high-end restaurants, and laboratories.
The glass is also less susceptible to fractures since it contains about 80 percent of silicon dioxide.
I looked at various customer reviews, and many users recommend this glass for use in the oven.
Glass Coated with Termite-Resistant Paint
In my research, I came e across a user who claimed that it’s possible to coat your glass bowl with termite-resistant paint. According to the user, this coating reduces the risk of glass shattering when exposed to heat.
Unfortunately, I couldn’t get any supporting evidence for this argument online. Consequently, I may not authoritatively recommend it.
What Type of Glass Can’t You Put in the Oven?
The glass that is not heat resistant can’t be safely placed in the oven like tempered glass.
Never put any non-tempered glass container in the oven.
A regular glass begins to crack and breaks at a temperature of 302–392°F. Therefore, putting non-tempered glass in the oven might crack or break inside as it can’t withstand oven temperatures.
Also Read: Can You Put a Whole Lemon in A Juicer?
How to Know If Your Glass is Oven-Safe
By looking at them, it is not always obvious to tell the difference between a regular and an oven-safe glass. However, here are a few signs to look out for.
Check the Label
Most tempered glass products are labeled in some way.
Some have the word ‘temp’ or ‘tempered’ stamped on the bottom or side.
Others you can simply tell by their brand name. For instance, Pyrex is one of the well-known brands of oven-safe glass.
Look at the Design
If the glass has no label, check its design features.
It is certainly not safe for the oven if it has a metallic trim or any kind of decoration.
Another design consideration is; what kind of an item is it?
Usually, serving bowls and drinking glasses are not meant for oven use. So, you can hardly find an oven-safe one.
On the other hand, glass casserole dish pans and baking trays are potentially used in the oven.
Although this method does not provide full proof of oven-safe glassware, it helps in giving a clue.
Inspect the Glass’ Condition
Tempered glass breaks differently from regular glass.
Large cracks form on a regular glass when it breaks. But when a tempered glass container breaks, it forms small, spider web-like cracks.
Caution: Never cook on broken glass cookware. If you spot a crack on the dish, discard it immediately.
The Causes and Prevention of Oven Glass Breaking?
While tempered glass is the best for cooking in the oven, it can easily break when subjected to certain conditions. These include:
Drastic Temperature Changes
There are many causes of glass breakage in the oven, but the thermal shock is one of the most common.
Glass, no matter how strong it is, is fragile to rapid temperature fluctuations. As such, putting glass cookware directly into the hot oven from the fridge or freezer is not recommended.
Tip: When using glass cookware in the oven, it is best to start from room temperature and then to a preheated oven.
The Wrong Type of Glass
Not all glass can withstand the oven heat. Only use tempered glass or other glasses labeled oven safe.
Never put small glass bowls and drinking glasses in the oven unless they have a label indicating that they’re oven-safe.
The same applies to the lids of your glass dishes. Ensure they also have an oven-safe label before using them.
Temperatures That Are Too High
Most oven-safe glass containers feature labels indicating the recommended temperature limit.
If the instructions are not on the label, they are somewhere in the user’s manual.
If you heat it beyond that limit, it’s likely to break.
Unfortunately, many people are not aware of these temperature limits.
Tip: Always stay below the manufacturer’s recommended temperature limit.