Annealed vs Tempered Glass

What is the Difference Between Annealed and Tempered Glass?

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If you are in the market for new windows or other glass areas for a building, you will hear about annealed and tempered glass. While the seller may be able to explain the differences to you, it is helpful if you already know the differences before you arrive at a showroom. It streamlines the process if you know what you want.

What is the Difference Between Annealed and Tempered Glass? During manufacturing, annealed glass is slowly cooled to room temperature after being treated with heat, but tempered glass is rapidly cooled after its heat treatment. The result is tempered glass being much stronger than annealed glass. For this reason, tempered glass is often used in areas of high impact to protect people from shattering glass.

It might seem like the type of glass you use for windows does not really matter, but it can actually have a big impact on your safety and needs. Tempered and annealed glass have different purposes, so it is important to know when to use each one. 

What is Annealed Glass?

During the process of manufacturing annealed glass, a thermal treatment is used to heat the glass up. Then, the glass is slowly cooled to remove internal stressors that could lead to the glass breaking easily. 

What are the Benefits of Annealed Glass?

When you start thinking about what you need from the glass you purchase, you should consider if the benefits of annealed glass are suitable for your needs. 

  • Annealed glass is an economical choice. For projects that are on a tighter budget, annealed glass is much less expensive than tempered glass or other alternatives. 
  • When you are wanting to add glass to a décor product, you will likely prefer annealed glass because it is cheap, and you do not have to worry about safety.
  • Annealed glass also can be shaped at any point. Because it is a softer glass, you can drill, cut, and notch annealed glass

What are the Cons of Annealed Glass?

Like any product, there are benefits and downfalls of annealed glass. It can be tempting to go with annealed glass because of its low price, but you still need to consider the possible negative aspects of deciding to use annealed glass. 

  • Annealed glass can cause significant physical harm if it is broken. Upon breaking, annealed glass usually breaks into big, jagged pieces. These shards are easy to cut yourself on, especially if you are close to the annealed glass when it breaks.
  • Annealed glass is not that strong. Because it lacks the strength of tempered glass, you should try to only use annealed glass in areas where you are not concerned about safety.
  • You might have to replace annealed glass more often. This is mostly due to its weakness. It can break quite easily. 

What is Tempered Glass?

Tempered glass is actually annealed glass that undergoes a different heat treatment to make it stronger. During the process of heating annealed glass so that it becomes tempered glass, temperatures of about 1,200 degrees Fahrenheit are used. The biggest difference in the heat processes between annealed and tempered glass is the rapid cooling of tempered glass. 

What are the Benefits of Tempered Glass?

Tempered glass has many benefits that make it a popular choice among people installing new windows or working on the glass areas of a new building.

  • Tempered glass is frequently called safety glass. It gets its name from the way that it breaks. Tempered glass usually breaks into lots of little pebble-like pieces that are not as likely to cause significant harm to anyone close by. 
  • It is difficult to break tempered glass. This makes it a favorite for people who want the windows of their houses to be hard to break into. Since it takes a lot of force to break tempered glass, it is also much less likely to break if hit by an object, like a bird or baseball. If it does break, the damage is usually not as bad as it would be with annealed glass. 
  • Tempered glass can sustain its shape up to around 470 degrees Fahrenheit

What are the Cons of Tempered Glass?

Although tempered glass is much safer and stronger than annealed glass, it does still have drawbacks that you should consider carefully. Ultimately, though, safety should be considered in conjunction with all pros and cons. 

  • The edges of tempered glass are the weakest, so impacts to those areas may cause the glass to break. Even though the center of the glass is strong, the heat treatment does not always extend to the edges.
  • You cannot drill or shape tempered glass. It will shatter. Any notching or finishing of the edges must be done while the glass is still annealed. The glass is not tempered until the shaping is completely finished. 
  • Tempered glass is more expensive. Because the process for creating tempered glass is more in-depth and requires additional heat treatment, it is more expensive than annealed glass. If you are on a budget, tempered glass may be out of your price range. 

How Do You Decide to Use Annealed or Tempered Glass?

Most of the time, it will be easy to decide if you need glass to be annealed or tempered once you consider your needs. The most important thing is making sure that you decide on the right type of glass for your project. It will be imperative for safety and for your budget.

When to Use Annealed Glass

Annealed glass should be used whenever safety is not a concern. This is why annealed glass is commonly used in pieces of décor. Annealed glass is also a good choice if you are not particularly worried about the strength of the glass. 

You will most likely choose annealed glass for areas that are far from the floor. This type of glass is often used in mirrors that have a solid backing. Its low price makes annealed glass a popular choice for decorative items or windows that do not have a high risk of breaking.

You do not want to use annealed glass if it will be a possibility that someone could fall into the glass. The jagged shards can pose serious danger. It is also smart to not use annealed glass for anything that might be easily broken. Otherwise, you will be spending a lot of money to constantly replace the glass. 

When to Use Tempered Glass

You might find that tempered glass is the best choice for your needs even though it is more expensive. If safety is involved, you should use tempered glass. It simply is much safer than annealed glass when it breaks.

Tempered glass is also a good choice when you live in an area that may have extreme elements like strong winds or hail. Tempered glass can usually withstand such elements much better than annealed glass. 

Sometimes, you may even be required to use tempered glass to comply with building codes. When you are constructing a new building, it is important to check with the codes of the International Residential Code

Certain situations require tempered glass. This includes doors, windows bigger than nine square feet, or less than 18” from the floor. It also includes anything within two feet from door hinges or anything within five feet of a water amenity like a shower or hot tub, or along stairways or ramps. 

Although it is more expensive, tempered glass is much safer. You will likely also save money in the long run because you probably will not have to replace tempered glass anywhere near as often as you would for annealed glass.

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