What To Ask Your Glazier: Types of Glass

What To Ask Your Glazier: Types of Glass

What To Ask Your Commercial Glazier About Types of Glass

Kensington Glass Arts recently began a series over what questions you should ask your glazier. The purpose of this series is to help general contractors, architects, and folks looking for glass upgrades select the best glazier for their upcoming projects. In our last article, we discussed how, and why you should ask your glazier about certifications. In this article, KGa goes over the different types of glass, their purpose, and how to ask your glazier about the types of glass they offer.

What are the different types of glass?

Before you ask a glazier what types of glass they offer, it’s good to know a bit about the various types of glass. Each type of glass has different manufacturing processes and serve different purposes. For example, some forms of glass may be primarily used for residential home windows. Meanwhile, other types of glass may be used for exterior large building windows. This is because different types of glass are fabricated at different heats, and receive different treatments to create variable appearances, thickness, and protectiveness. Below, we discuss the various different types of glass, how to ask an organization what types of glass they offer, and how to ask an organization about special ordering glass.

Float Glass

Float glass is a basic raw material used in the production of more specialized products, but also the most common form for all applications. This type of glass made by floating molten glass on a bed of molten tin. It is this floating of molten glass that produces flat surfaces seen in glass today. Because float glass is the most basic form of manufactured glass, it’s primarily used for smaller projects, such as small residential windows, tabletops, and mirrors. To learn about how float glass is made, check out this video by Pilkington Glass on their float glass process.

Pilkington USAFloat Glass Process
Annealed Glass

Annealed glass is made by a controlled cooling of float glass during the process to stabilize the glass. Most float glass is annealed to control the product quality and properties. The glass is cooled at a specific rate to make it less brittle. When annealed glass breaks, it breaks into large, jagged pieces. Annealed glass is primarily used for tabletops, basement windows, cabinet doors, and more.

Heat-Strengthened Glass

When annealed glass is uniformly heated then cooled at a specific rate in the fabrication process, the glass becomes twice as strong with the same size and thickness. This type of glass is known as heath-strengthened glass. Heat-strengthened glass is often used for general glazing purposes when there are no safety code requirements, such as window units.

Tempered Glass

Image of a type of glass, tempered glass, fabricated by Kensington Glass Arts (KGa)
Tempered glass fabricated by Kensington Glass Arts

Tempered glass is made by heating annealed glass to a near-molten state then blowing compressed air uniformly on both sides in a process called quenching. As such, tempered glass is twice as strong as heat-strengthened glass and four times as strong as annealed glass. When tempered glass breaks, it shatters into many small cube-shaped pieces to minimize injury on impact. As such, tempered glass is considered a form of safety glass. We will discuss safety glazing further in our section about laminated glass.

Kensington Glass Arts fabricates tempered glass for a variety of construction uses, including glass shower doors, office dividers, storefront glass, building envelope, and more. You may also see tempered glass used in common appliances like ovens, technology screens, and coffee machines. Tempered glass can also be produced into a laminated glass through a secondary process, producing tempered laminated glass.

Clear Vs. Low Iron Glass

When discussing tempered glass, it’s important to discuss the difference between clear tempered glass and low iron tempered glass. The name “clear” glass is a bit of a misnomer. Clear glass is actually slightly green. You can see the green coloring on the side of the glass. Low iron glass is, in actuality, more clear than clear glass. Low iron glass does not have the green tint that clear glass does, most notably when viewed on the edge where you are viewing through more glass material than when viewed face-on through the thickness of 1/4″ – 3/4″ of material.

Laminated Glass

Laminated glass refers to the process of bonding two or more pieces of glass with a thin layer interlayer of polymer between the two or more glass pieces, which fuse under heat and vacuum. There are 3 predominant interlayer types (PVB, EVA, SGP) which each have unique properties to support the characteristics of glass in different forms. When laminated glass breaks, it sticks to the interlayer, which mitigates the risk of breakage. Because of this, laminated glass is used in car windshields to protect you in an accident as well as in commercial applications where the risk of impact breakage is increased. Laminated glass is also considered a form of “safety glazing”.

Safety Glazing

Safety glazing is any one of the multiple forms of glass with enhanced characteristics, which reduce its risk of breakage or how it breaks. This can include tempering, laminating, or a combination depending on the application and characteristics required. Security glazed laminated glass is used in prisons, psychiatric hospitals, banks and other places with strict security requirements.

Annealed Laminated Glass

Annealed laminated glass is, as it sounds, multiple layers of annealed glass laminated together. The benefit of this form is that it can be produced in bulk then fabricated to exact application-specific size and details afterward making it incredibly flexible in use, although less durable and impact resistant.

Tempered Laminated Glass

Tempered laminated glass railings

Before laminating, you have the opportunity to create tempered laminated glass. First, identical glass shapes are fabricated. Then, the glass goes through the tempering process. Afterward, the glass goes through the lamination process. This multi-layer glass has the strength of tempered glass when broken. It also provides the benefits of laminated glass, by sticking together when breaking, preventing shattering, or leaving unprotected openings in railings. Tempered laminated glass is able to withstand repeated impacts before breaking. View the video below to see a comparison between tempered glass, laminated glass, and tempered laminated glass breakage.

Dupont Sentry Glas[s] –
The Wagner Companies

Each form of glass has specific applications that a knowledgeable fabricator can help guide you through the selection process.

Insulating Glass

aluminum profile and insulated glass(3D rendering)

Insulated glass units (IGU) are made with two or more pieces of glass separated by sealed airspace. Insulated glass is primarily used in residential and commercial exterior windows. This is because insulated glass units are an “effective way to reduce air-to-air heat transfer through the glazing.”

Low-E Glass

Low-emissivity glass, aka low-E glass, is treated with a thin metallic coating to minimize the amount of heat and infrared light passing through the glass. Often, parts of insulated glass units are made with Low-E glass to combine both the benefits of air gap insulation and low-E glass.

Fire-Rated Glass

Fire-rated glass is a form of specialty glass that defends against the spread of fire and smoke. In order for a glass to be considered fire-rated, it must undergo many tests to determine the specific performance characteristics and duration of exposure before failure. Fire-rated glass can survive heat as high as 1600° F. Fire-rated glass can be used in many different types of structures. However, it is most commonly used for interior glazing purposes, not exterior glazing purposes.

Specialty Glass

There are numerous types of specialty glass made from all forms of the previously discussed forms of glass. For example, patterned glass is simply any type of glass that when fabricated, has patterned rollers on the molten glass to embed a pattern, or backpainted through a variety of painting processes, creating unique and artistic effects.

Acid Etched
Acid-etched glass, a type of glass

Acid-Etched glass refers to an annealed type of glass that has been treated with hydrofluoric acid to create a frosted effect. Since this type of glass is created with acid treatment, this glass can be used for many different purposes. These include glass doors, railings, wall partitions, shelving units, and more. Once acid-etched glass is fabricated, it can then be tempered or laminated for additional security.


Mirrors are another type of annealed glass that has been treated with a metallic substance on one side to create reflective-like properties. In terms of the practical use of mirrors, that is fairly self-explanatory. Mirrors are often installed in both residential and commercial construction buildings, in bathrooms, bedrooms, and more.

What types of glass does your organization offer?

Now that you have an idea of what some of the various types of glass are, you’ll be able to confidently understand an organization’s answer to this question. Some companies are suppliers, fabricators, or glaziers. Depending on what type of organization you’re speaking to, you may get different answers from each. A glass supplier is an organization that holds several types of glass that can be provided for a project. However, a glass supplier is not the organization that produces the glass. A glass fabricator is an organization that actually processes glass to create a finished product ready to be installed. Meanwhile, a glazier refers to the individuals who actually installs the glass.

Kensington Glass Arts is unusual, in that we are both a glass fabricator and installer. Kensington Glass Arts manufacturers tempered glass, laminated glass, and tempered laminated glass in house. We install both glass we manufacture and specialty glass from other organizations. This allows us to cater to all our clients’ needs. Some of our clients are only fabrication customers, who purchase glass for their own installation. Some customers only use our glazing services to install at their projects. Other clients both purchase our glass and use our glaziers to install the piece of glass. Sometimes, we find our glaziers working alongside our fabrication customers as they install the glass we prepared for them.

Many organizations only fabricate a few types of glass at their manufacturing facilities. However, the organization may install a large variety of glass. In this case, the organization often special orders the glass from one of their trusted vendors. These vendors may not have the ability to install glass, so the vendors rely on glaziers to install the glass.

What type of glass would you recommend for my project?

This question will help you make an informed decision about if the glazier is right for your project. Firstly, this allows the organization to showcase any special projects or interesting products they have access to for your project. Secondly, you have the opportunity to discuss with an organization if they suggest an unexpected type of glass. For example, if you expected to receive a tempered door and the organization suggests tempered laminated glass, you can have a conversation about the details of the project and make an informed decision with the assistance of your glass fabricator.

If you do not have the best type of glass for my project, can you special order it?

As discussed earlier, sometimes you may trust a glazier for an installation, but they are unable to fabricate the type of glass you need for the project. In this case, it’s valuable to ask if they can special order the glass you’d like installed. For example, some of KGa’s clients request decorative glass, such as etched glass, carved glass, or back-painted glass. In this case, Kensington Glass Arts may turn to a skilled partner that produces the required specialty material. There are many suppliers as there are specialty glass types, and KGa is known and familiar with most of them given our 45 years in the industry.

About Kensington Glass Arts

Exterior of Kensington Glass Arts Ijamsville Facility

Kensington Glass Arts is a commercial glass fabricator, installer, and service provider. Kensington Glass has four convenient locations in the Mid-Atlantic and Virginia area. We offer 3-day delivery for our fabricated glass to qualifying customers. To learn about our 3-day delivery, visit our Contact Us now page!