Annealed Glass vs. Tempered Glass vs. Laminated Glass: A Commercial Glass Cheat Sheet

Glass Industry terms can sometimes be daunting.  From annealed glass to fenestration, there are countless technical terms that can be intimidating to a casual observer or to anyone who is entering into the glass industry for the first time.  That’s why we’ve compiled a short explanation of the three major types of glass you’ll encounter.

 Annealed Glass

This type of glass is the simplest form of the float process as annealed glass is the cooled sheet that comes directly from the furnace.

Annealed glass is the easiest glass to shape and polish, and is by far the most customizable to customer requests.  However, this comes at the cost of easy breakage.  Annealed glass that shatters breaks off into large sharp shards and poses obvious safety risks. Annealed glass is not considered a safety glass (meaning glass with additional safety features that makes breakage is less likely or, when broken, less likely to pose a dangerous risk).

Typically, annealed glass is used in areas that don’t come into direct contact with people such as basement windows in a home.  Using annealed glass in areas where there is a high chance of human contact or traffic, such as shower doors or railings, is not only dangerous but may also be unlawful because it is not nationally recognized as a safety glass.

 Tempered glass

Tempered glass is made in a similar process to annealed glass. In essence, tempered is just annealed glass that has been heated and cooled repeatedly and rapidly. The result of this process is a sheet of glass that is five times stronger than annealed.

Instead of breaking into large and sharp shards as annealed glass would do, tempered glass breaks into tiny fragments without any large pieces that could potentially do damage to people or pets. Due to this strength and shatter style, tempered glass is considered a safety glass. This basically means that it can be used in high traffic areas like sliding doors, shower enclosures, and railings.

If you’re interested in seeing the different shatter patterns firsthand, we recommend watching what we find to be an excellent video by Ted Halladay at Glass Guru who describes (and smashes) these two different types of glass.

 Laminated Glass

Laminated glass is the only choice when safety is paramount. This type of glass is created by placing an interlayer between two sheets of glass.

Interlayers are typically made from a compound called polyvinyl butyral, more commonly referred to as PVB. This interlayer holds the piece of glass in place if it is smashed, leaving a shattered but unbroken sheet.

The shatter pattern is something you really should see. Notice how the glass shatters, but doesn’t fall apart. That’s the interlayer holding it all together. This is also how bullet resistant glass functions, but at a much stronger degree.

If you want to learn more about the polyvinyl butyral interlayer, read about it in our other post on how interlayer works


While there are numerous other types of glass, this basis of knowledge should help to serve as a building block. If you would like to subscribe to more posts like this, sign up for our Glass Buyers Monthly

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