Difference Between Annealed, Tempered, & Laminated Glass

Annealed Glass

Annealed glass, also known as float glass, has been slowly cooled once it has been formed. This slow cooling process reduces internal stresses within the glass, adding strength and reliability.

Pros

• Annealed glass is one of the cheapest types of glass to manufacture.
• Annealed glass can easily be cut or drilled without breaking, making it extremely easy to work with.

Cons

• Annealed glass is not very strong, so it cannot take extreme temperatures or thermal shock.
• When annealed glass breaks, it will break into sharp jagged pieces that can easily cut or injure someone who comes in contact with them.
• Larger pieces of glass may require a Kiln to make sure that they can properly control the temperature at which the glass cools.
• If the glass is not cooled or “annealed” properly, it becomes very brittle and may even break spontaneously.

Common Uses

Annealed glass is typically used for things like tabletops, cabinet doors, and windows.

Tempered Glass

Tempered Glass is any annealed glass that is rapidly cooled after being formed. This rapid cooling causes internal stress as the outside cools before the inside.

This tempering and internal stress creates a glass that is 4 to 5 times stronger than regular annealed glass.

Pros

• Tempered glass is 4 to 5 times stronger than annealed glass.
• Tempered glass can handle much higher temperatures than annealed glass.
• Because of the internal stress caused by rapid cooling, tempered glass breaks into small granular chunks, not sharp shards like annealed glass. This is where it gained its common name of “safety glass.”

Cons

• Tempered glass is more expensive because it requires the extra step of rapid cooling after the initial annealing process.
• Tempered glass cannot be cut or drilled after being cooled. This means that cutting or drilling the glass must be done while it is being formed and still hot.

Common Uses

Tempered glass is typically used for things like passenger vehicle windows, shower doors, architectural glass, plates, and cookware.

Like annealed glass, it can also be used in tabletops and windows if there is a high risk of breakage. It is also used in a corporate setting where if someone is injured by the broken glass, they might be liable.

Laminated Glass

Laminated glass consists of a layer of plastic sandwiched between two pieces of glass.

The plastic bonds these two layers together so that if the glass is broken, it still remains in one piece.

This creates the spider-web effect you often see when a windshield is cracked. Because it doesn’t shatter, this type of glass is also referred to as “safety glass.”

The plastic used to bond the glass usually consists of Polyvinyl Butyral (PVB), Ethylene-vinyl acetate (EVA), or Thermoplastic Polyurethane (TPU).

Laminated Glass can be made of either Annealed or Tempered Glass. What makes it laminated glass is the plastic layer used to hold the glass together

Pros

• Laminated Glass is used in situations where if the glass broke, even if it wasn’t sharp, it may harm someone. An example of this would be a car windshield. Even if you used tempered glass in a windshield, the velocity of the small granular pieces could still seriously injure someone. This is why laminated glass is used because it ensures that the whole windshield, even while broken, will still remain in one piece.
• Because they have multiple layers of glass and naturally acoustic absorbing plastics holding them together, laminated glass makes an excellent glass for soundproofing.

Cons

• Laminated Glass is more costly than annealed or tempered because it requires the fusing of two different sheets of glass together using a plastic inner layer. This increases production costs.

Common Uses

Laminated Glass is typically used for protection in places like banks, money-exchange centers, jewelry shops, or museums. In the windows and doors of areas where hurricanes are common and in car windshields.

But they also work for soundproofing things like train or airplane windows, recording studios, and hotels.

Other Varieties of Glass Can Be Found Below