A-Z Glass Glossary

In this guide, we’ll take you through some of those confusing yet important glass terms and vocabulary. After this, you’ll be up-to-date with the latest glazing terminology and be confident in understanding complex terms.


This process involves rounding the edges of glass and taking the sharp edges off of it.


Glass shapes with bevelled edges can be used as a decorative option that can enhance the look of windows and doors. They are bonded to glass surfaces with strong UV adhesives.


Excess moisture on windows and doors that is caused by lack of ventilation, this means that stale damp air struggles to be replaced by fresh air outside.


The goal of this system is to remove all traces of moisture from a window and stop it from fogging up during manufacture.


This is the ability of a surface to radiate energy, the lower the emissivity on windows the better their insulating properties are.

Flush glazing:

Glazing in which the glass sits flush with the frame and does not have any protruding fixings.

Glazing bead:

The piece of vinyl which sits on the edge of the glass, keeping the glass secure in the frame.

Hard coated:

Also known as pyrolytic coating, this is used to make glass more durable and less susceptible to scratches and degradations.


This is a coating which is commonly used for fire protection; it expands as a result of heat and forms an insulating layer, protecting the structure of windows or doors.


Jumbo is the biggest size of glass a manufacturer can supply to a customer; these sizes can range depending on the supplier. 


This is a term which is commonly used in the construction industry. It measures how well a material can conduct heat, glass with a low K-value does not let heat energy pass through very easily.

Linseed oil putty:

This is a traditional glazing compound, used for re-glazing windows and doors. The putty is applied around the frame and pressed in using a putty knife blade to ensure a smooth finish.


A window design with a vertical divider that separates the window. Mullioned windows are well-known, seen through-out Western and Islamic architecture.

Newton rings:

Concentric rings appear on faulty windows, when a spherical layer is next to a flat surface of glass, causing light reflection between the surfaces.

Online & offline coatings:

During the manufacturing process of glass online coatings are applied to make the glass highly durable. Whereas offline coatings are used after the glass has been manufactured, this process applies reflective properties, such as solar protection to the windows.

Patent glazing:

This type of glazing is used in overhead glazing, for example conservatory roofs and roof lights. They allow natural light in and act as a draining system for rain water.


The quenching process involves heating glass and cooling it quickly to harden the glass. The glass becomes 4 to 5 times stronger after the process.

Roller wave:

This is a type of window design that is created during the quenching process. The hot glass is passed through rollers which reduces the surface flatness and as a result makes the reflection of the glass bend.


Sandblasting equipment compromises of an air compressor, sandblaster and blasting cabinet which are used to etch decorative patterns into glass.

Triple glazing:

3 panes of glass are installed instead of the traditional 2 panes. It is considered to be the most energy efficient and has the best noise reduction.

U value:

This is a measurement of the effectiveness of glass as an insulator. The lower the u-value, the better the glass is at retaining heat on a cold day and the better it is at stopping heat from entering on a hot day.

Vent hole:

Also known as trickle vents, these help the circulation of air flow in a home, replacing damp air with fresh air from outside. This improves problems with damp and condensation.

Wind resistance:

High impact windows are a certain type of window which has high wind resistance properties. They consist of strengthened glass which reduces the impact of any flying debris.

X-ray glass:

X-ray glass comes in many forms, including laminated, lead, encased and many more. Commonly seen in a radiology, x-ray room and other hospital departments.

Young modulus:

Also referred to as elastic modulus this is a measure of firmness of an elastic material. The modulus looks at how easy it is to stretch a material, like glass.


A window zipper deglazing tool is a steel blade which is used to cut through dried paint and hardened window caulk so that new glazing can be put in its place.

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