# What Is Tempered Glass & How Is It Made? | GW GeWalt

> Tempered glass is heat-treated to be up to 5x stronger than annealed glass and shatters into blunt pieces. Learn how thermal toughening works.

URL: https://gwgewalt.com/guide/what-is-tempered-glass-and-how-is-it-made/
Last-Modified: 2026-07-10

# What Is Tempered Glass and How Is It Made?

Tempered glass is heat-treated to be up to 5x stronger than annealed glass and shatters into blunt pieces. Learn how thermal toughening works.

Published 10 July 2026 · 5 min read

![Large tempered glass door panel in a Malaysian showroom with sunlight through it](/images/featured/large-tempered-glass-door-panel-in-a-malaysian-sho.webp)

## The Material Behind Every Serious Glass Door

Tempered glass — also called toughened glass — is ordinary float glass transformed by heat treatment into a safety material. It is up to five times stronger than the standard annealed glass it starts as, and when it does break, it crumbles into small blunt granules instead of dagger-like shards. Those two properties are why it is the required material for 

tempered glass doors

[/tempered-glass-doors/ →](/tempered-glass-doors/)

, shopfronts, shower screens and balustrades.

## How Thermal Toughening Works

The process is elegant. A finished panel — already cut to size, holes drilled, edges CNC-polished — enters a tempering furnace and is heated to around 620°C, near its softening point. It then hits quenching jets that blast both faces with cold air simultaneously.

The surfaces cool and solidify first while the core is still contracting. As the core finally cools, it pulls the already-rigid surfaces inward, locking the outer layers in permanent compression and the core in tension. Glass fails from surface cracks — and a surface under compression resists cracking until an impact overcomes the locked-in stress first. That built-in pre-stress is the entire trick.

The same stress balance dictates the break pattern. Pierce the compressive skin deeply enough and the tensioned core releases all its stored energy at once, shattering the whole panel into granules.

![Tempered glass safe-break granules close-up](/images/content/close-up-of-tempered-glass-safe-break-pattern-show.webp)

> **Why fabrication comes first**
> 
> Because the panel’s strength lives in its stress balance, tempered glass can never be cut, drilled or ground after toughening — any breach shatters it. Every dimension, hinge hole and polished edge is finished before the furnace. This is why we measure your opening exactly (RM50, deductible) before fabricating anything.

## From Furnace to Your Doorway

In door applications, tempering solves both everyday and worst-case problems. Day to day, the strength shrugs off trolley knocks, wind slams and the general abuse a busy entrance takes. In the worst case, the granule break pattern turns what would be a serious laceration event with annealed glass into broken glass on the floor.

Malaysian practice formalises this through the MS 1498 safety-glass standard, which our panels comply with — our guide on 

how strong tempered glass is

[/guide/how-strong-is-tempered-glass-ms-1498/ →](/guide/how-strong-is-tempered-glass-ms-1498/)

 unpacks the standard and the 5x figure in detail.

We fabricate tempered panels in 10mm, 12mm and 15mm thicknesses, transparent or frosted, for doors, partitions, railings and shower enclosures. If you are planning a glass door or shopfront, send us the opening size and we will quote material, hardware and installation together — starting from RM2,000 with free Klang Valley delivery.

## Frequently Asked Questions

Why is tempered glass stronger than normal glass?

Thermal toughening locks the glass surface in compression. Any impact must first overcome that built-in compressive stress before it can start a crack, which is what makes the panel up to five times stronger than annealed glass.

Is tempered glass safe when it breaks?

Yes — that's half its purpose. Instead of large sharp shards, it crumbles into small, relatively blunt granules, dramatically reducing injury risk.

Can tempered glass be cut after tempering?

No. Cutting, drilling and edge-polishing must all happen before toughening. Any attempt to cut a tempered panel shatters it, which is why exact measurement comes first on every order.

## Learn more about Tempered Glass Doors

See how we spec, supply and install tempered glass doors — or send us your questions for a free quotation.

Tempered Glass Doors

[/tempered-glass-doors/ →](/tempered-glass-doors/)

 

Get a Free Quotation

[https://wa.me/60192404794?text=Hi%2C%20I%27d%20like%20a%20free%20quotation%20for%20a%20door%20or%20glass%20system. →](https://wa.me/60192404794?text=Hi%2C%20I%27d%20like%20a%20free%20quotation%20for%20a%20door%20or%20glass%20system.)