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What Is Annealed Glass?

Annealed glass has undergone a cooling treatment at a glass fabricator’s float plant as a way to improve durability.
Published March 06, 2018

What-is-Annealed-GlassGlass is a major design component utilized in both commercial and residential construction projects—and for very good reasons. From its beauty to its versatility to its practicality, glass can serve a wide range of functions. Many may not realize, however, all the various treatments it can undergo to maximize its customizable properties prior to installation.

Annealing glass is one such technique utilized by glass fabricators and manufacturers.

The term, "anneal," is mainly used to describe the glass-cooling process that is performed at a fabricator's float plant. It is not treated with heat, unlike tempered glass.

Performed by highly skilled technicians with the help of precise, efficient equipment, the annealing process improves the glass' durability and helps to reduce internal stresses that could result in breakage. Keep in mind that annealed glass may also be referred to as non-tempered and/or float glass.

While this type of glass can be edged and polished, custom-cut and drilled to create an array of products, including windows and cabinet doors, it does have its disadvantages, however, and glass that is improperly annealed has an increased possibility of cracking or shattering.

Annealed glass is not as strong as tempered glass, which is why fabricators more often opt to temper the material.

Here's why: Annealing glass actually rids it of internal stresses, while tempering glass does the opposite. The final stage of the latter is to quickly cool the hot glass by blasting it with cold air—called quenching—after it has been treated in a tempering oven. 

The inner layer cools slower than the outer layer, which causes the tension that makes tempered glass four to five times stronger than annealed glass.

Annealed and tempered glass also differ regarding safety. Not only does the strength of tempered glass surpass annealed glass products, but the breakage patterns are safer, as well.

For example: If by some chance a tempered glass display case breaks, it will fracture into smooth, relatively harmless pieces. On the other hand, an annealed glass window, for instance, will break into sharp, jagged pieces that could potentially hurt someone in close proximity.

Due to the fact that this type of glass can be cut, drilled, and fabricated, it is typically the raw float glass material fabricators use. There are some rare instances in which safety glass is not required for a project and, as a result, the fabricated glass is left in its annealed state. However, because almost all glass utilized in construction for retail display cases, windows, and office walls, among other applications, must be safety glass, annealed glass is put through the tempering process in the final stages of fabrication. The result is tempered safety glass customized to meet the needs of your project.

Learn more about commercial glass industry products by contacting a trusted glass manufacturer, such as Dillmeier Glass, who can recommend the best solutions for your next project.

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