Toughened Glass FAQs

Everything you need to know about Toughened Glass

Toughglaze is an established and world-renowned leader in the manufacture of glass including Toughened Glass and we have been in operation since 1993. Over the years, we have grown by heavily investing in our state of the art production equipment, processes and facilities. We continually focus on improving the efficiency of our production methods, ensuring 100% quality of the glass we manufacture and supply. We are glass experts and we know everything that needs to be known about the manufacture and supply of quality glass products. We offer our services for small, medium and large domestic and commercial projects and our glass range enables you to create bespoke designs with safe products complying to BS EN standards as listed on our Kite Mark Licence.

What is the difference between toughened and tempered glass?

Toughened glass is also known as Tempered glass and they are the same types of glass. It is a safety glass processed by controlled thermal or chemical treatments to increase its strength compared to normal glass. 

In this article, we refer to toughened, safety and tempered glass as they are the same glass product.

What is toughened glass?

Toughened glass, also referred to as tempered glass is physically and thermally stronger than normal glass. The prime function of any toughened glass is to ensure if broken for whatever reason then it breaks safely. The manufacturing process also increases the strength of the glass and makes it 4 – 5 times stronger than normal annealed or regular glass. It is ideal for many applications especially when incorporated into lamination.

If tempered glass is broken the stress contained from its manufacturing is released and results in the glass breaking into small harmless pebble-like particles.

Toughened glass is now required by regulation for every building project due to its increased strength and safety characteristics.

Is toughened glass fire rated?

There is a difference between Fire Rated Glass and Toughened Glass and some safety glass should not be used where fire resistance is also needed. Fire rated glass uses at least two panels of toughened glass and the cavity between each sheet of glass is filled with a transparent intumescent gel interlayer. In the event of a fire, the interlayer reacts to the heat, expands and reacts creating an effective safety barrier from the radiant heat of a fire. The number of interlayers and glass sheets depends on the fire rating required.

Fire Glass is needed in residential and commercial projects to protect essential escape routes in the event of a fire. It is used to protect stairwells, close by buildings and access doors and points.

Building Regulations determine what fire resistance glazing is needed for any residential or commercial buildings.

Is toughened glass more expensive?

Tempered glazing is not always more expensive than other types of glass and it really depends on the size and spec of the glass that you need. Laminated glass tends to be more expensive and heavier than tempered glass.

Is toughened glass heat resistant?

Tempered glass is heat resistant, however, be aware that it is not fire resistant unless it is manufactured to be fire resistant as well.

What temperature can toughened glass withstand?

Tempered glass can withstand temperatures of up to 243 C. Tempered glass is regular glass that has been strengthened through thermal or chemical treatment.

Is toughened glass breakable?

Yes, tempered glass is breakable, however, the manufacturing process it goes through increases its strength and makes it 4 – 5 times stronger than normal annealed or regular glass. The prime function of any tempered glass is to ensure if it is broken that it breaks safely by shattering into thousands of tiny pebble-like pieces. This eliminates the dangerous sharp edges and flying shards of regular glass when it’s broken. The prime function of any tempered glass is to ensure if it does break that it breaks safely.

What is the difference between toughened glass and regular glass?

Toughened glass is also known as safety or tempered glass and it breaks down into thousands of small pieces that have less sharp edges. This is as a result of the annealing process where the glass is cooled down slowly, which makes it stronger, impact and scratch resistant compared to regular glass.

Is toughened glass laminated?

Tempered glass is not normally laminated. Laminated glass can be manufactured with the flexibility to include an array of colours or interlayers to achieve the desired look, including thickness, heat resistance or impact resistance. Laminated glass can also go through the tempering process.

What is laminated glass?

Laminated glass is a safety glass that holds together when shattered. When broken it is held in place by vinyl interlayers that are between the layers of glass. Laminated glass is stronger than regular glass due to its interlayers and it stands up to greater impact compared to other types of glass. If a laminated glass is broken, the interlayer holds the pane of glass in place, leaving no sharp, jagged, dangerous holes for anyone to use to break in or hurt themselves on. Laminated glass is used in car windscreens and most shop fronts.

Is toughened glass double glazed?

Tempered glass is not double glazed.

Can toughened glass be cut?

Yes, tempered glass can be cut but it has to be done before the toughening process happens.

Can toughened glass be drilled?

Tempered glass can’t be drilled and if it is the glass will completely shatter. If you want a hole drilled in tempered glass, the hole or any other shaping needs to be done before the toughening process. When all the preparation of the glass such as; drilling, notching and edgework and any printing have been completed the toughening process can begin.

Can toughened glass break?

Tempered glass can break and the most common causes for it breaking is damage caused during installation, including nicked or chipped edges which can later develop into larger areas which have normally radiated from these defect points. The tempered glass then shatters into thousands and thousands of tiny pieces as a whole pane.

Can toughened glass be recycled?

Unfortunately, tempered glass can’t be recycled as it contains a mix of chemicals from its production and this means it has a different melting point to glass bottles and jars, therefore it isn’t possible to recycle.

Toughened Glass

Can toughened glass crack?

Tempered glass can crack and a tiny crack normally results in the whole pane of glass shattering into the tiny pieces which are the main benefit and safety aspect of it.

Can toughened glass be cut down?

Tempered glass cannot be cut after it has been toughened as it will break into thousands of the small round pebble-like pieces.

Can toughened glass be re-cut?

Toughened glass can’t be cut and it will shatter into the thousands of tiny pieces if it is. It can be cut and prepared before the toughening process which is what normally happens.

How does toughened glass break?

Tempered glass panes are broken and shattered into thousands of tiny pieces, much like tiny, tiny pebbles, protecting anyone around it from the dangers of large dangerous shards or glass.

How is toughened glass made?

Tempered glass is made by the glass being passed through an oscillating furnace and heated to around 630 C. Once the heating process is completed, the glass is transferred to the quenching chamber where it is rapidly cooled. This process changes the structure of the glass, creating a highly compressed stress surface. If the glass is broken the contained stress is released and results in the glass breaking into very small harmless particles.

How is glass toughened?

Regular glass is passed through an oscillating furnace and heated to around 630 C. When the heating process is completed, it is transferred to the quenching chamber to be cooled rapidly. The cooling process changes the structure of the glass and it creates a compressed stress glass surface. If the glass is then broken the contained stress is released and it results in the glass breaking into thousands of very small pebble-like pieces.

How is toughened glass cut?

Tempered glass is always prepared and cut to size before the toughening process.

How do you identify toughened glass?

  1. Look for the Kitemark which manufacturers are required to identify it with. There should be a stamp in at least one of the corners or the pane of glass. The stamp may say Tempered, Temp or Toughened and it is either sandblasted into the glass or applied as a porcelain overlay
  2. If you run your finger along the edges of the glass and the edges are smooth then it is likely the glass has been toughened. This is providing the glass is in good condition and the roughness isn’t a result of abrasion over its use
  3. Look for any surface scratches on one side of the pane of glass. If any are visible then these may have occurred from debris left over from the toughening process. This happens if the glass isn’t properly cleaned before it is heated. Small particles can melt and fuse onto the glass and the debris gets dragged along the surface causing small scratches during the cleaning part of the toughening process
  4. If you view toughened glass in the sunlight with polarised glasses you can see dark or shady lines running through it. These lines come from the rollers the glass is rested on during the toughening process
  5. As an absolute last resort, you can tell if a glass is toughened by scoring a line on it with a window cutting tool. If the glass is toughened it will make a glittery and uneven line. If the glass is regular glass the window cutting tool will make a clean, white line. It is always better to consult with a window specialist rather than do this yourself as if you score tempered glass too much it will shatter into the thousands of tiny pieces

How strong is toughened glass?

A tempered glass should be 4 – 5 times stronger than normal annealed or regular glass.

How do you clean toughened glass?

The best way to clean toughened glass is the same way you would clean regular glass. Use warm soapy water and then wipe it dry and clean with a microfibre cloth or kitchen towel.

How do you cut toughened glass to size?

If you need your glass a specific size or shape then it always needs to be cut before it goes through the toughening process. Cutting it after this will not work as the whole pane will shatter.

How to remove a toughened glass?

Toughened glass is removed by heating the edges to remove them from any surrounding frames. We strongly advise you don’t try and remove toughened glass yourself as there is a high chance of the pane shattering. Always get advice from a glass specialist like Toughglaze UK if you need to do this.

How thick is toughened glass?

Tempered glass comes in a range of thicknesses and it depends on what you are using it for as to how thick it should be. It ranges between 5 to 19mm and 6mm is the absolute minimum use for public areas. An expert and specialist glass manufacturer like Toughglaze UK can advise you on the thickness of your toughened glass and building regulations will dictate this most of the time.

How do you smash toughened glass?

You would have to hit tempered glass a lot harder than regular glass to smash it. As it is 4-5 tougher this generally means it takes 4-5 times more force to break it. If it does break on impact then the whole pane will shatter rather than leaving any jagged holes or edges where the impact has been made.

How do you test toughened glass?

Specialist glass manufacturers will test that the toughened glass they produce meets all of the quality and kitemark standards.

Toughglaze’s whole production process is controlled and monitored to ensure their products conform to the required standard BS EN 12150 and each one is tested and approved to BS EN 12600. The prime function of any tempered glass is to ensure if it breaks for whatever reason that it breaks safely. Toughglaze also recommends that all tempered glass is heat soak tested to reduce the chance of any spontaneous breakage after installation.

Be aware that tempered glass can be broken and if it is not installed correctly then this can cause it to shatter there and then or at a later time. If a tempered glass does break it does not necessarily mean the glass was faulty in any way and a reputable glass manufacturer will be able to show you the testing that the glass went through during its manufacturing process.

How do you grind toughened glass?

Toughened glass is not cuttable or grindable and it will shatter if you attempt it. This is why it is so important to use a specialist glass manufacturer to make sure the glass you are using is manufactured to your exact measurements.

What temperature can toughened glass withstand?

Toughened glass can withstand constant temperatures of up to approx 243 degrees C but this will vary by manufacturer so always refer to them if it will be exposed to abnormally high temperatures.

What is clear toughened glass?

A clear toughened glass is regular clear glass that has gone through the toughening or tempering process, making it 4-5 times stronger.

What is laminated toughened glass?

A toughened laminated glass is even stronger than toughened or laminated glass and it is produced to customers specifications. It offers total flexibility to select a vast array of glass or interlayers to achieve customer expectations.

Laminated Toughened glass can incorporate glass panes of varying thickness from 4mm -19mm and it can have a normal or satin finish with the possibility to silk screen or digital print to customer requirements.

What is tempered toughened glass?

A tempered toughened glass is the same as either tempered or toughened glass. Tempered and toughened glass are the same, they are just to referred to using the different names.

What is heat soaked toughened glass?

Heat-soaking is a method that reduces the possibility of spontaneous breakage in tempered glass. Heat soak testing is a process that is used by excellent glass manufacturers and it reduces the likelihood of spontaneous breakage sometimes months or even years after installation

After the glass is toughened Toughglaze position the individual glass panels on special racks and they are placed inside a calibrated oven. The glass is then heated for two hours and stabilised at 280 – 300 C. This temperature is maintained for a further two hours and then the glass is allowed to cool for two hours or until it gets below a certain temperature. Any breakages detected at this stage are replaced and the sequence starts again.

Although this test prevents a lot of breakages in the future, other breakages can still occur.

Where is toughened glass required?

Building regulations for glass have been applicable to all glazing replacements or installations from 1st April 2002. The regulations also apply to thermal performance as well as safety, air supply, means of escape and ventilation.

An external window or door is a “controlled fitting” under the Building Regulations and as a result of this these regulations set out certain standards when a window or door is replaced.

Safety glazing should be installed for any glass in a critical area.  Below is a list giving a general view when a toughened glazing is required:

  • Any glazed area within a window below 800mm from floor level
  • Any glazed area within a window that is 300mm or less from a door and up to 1500mm from floor level
  • Within any glazed door up to 1500mm from floor level

Where is toughened glass used?

Tempered glass is now used the most due to the change in building regulations from 1st April 2002.

It is used in domestic and commercial windows and doors, emergency exits, car windows, shower doors, tables, refrigerator shelves and many more. The reason it is used most is that when it breaks it shatters into thousands of tiny round pebble-like pieces rather than sharp jagged shards of glass, making it safer for anyone or any other structures around.

Where to buy toughened glass?

If you are looking to buy tempered glass then you should always purchase it from a reputable glass manufacturer who will have the processes and checks in place to ensure it meets all safety and kitemark standards. In the unlikely event that it does break you want to ensure it shatters into the tiny pieces so no one around is injured.

Where do I need toughened glass?

You need to use toughened glazing in doors, windows, partitions and generally, anywhere it forms part of the structure of a building, and this is guided and regulated by building regulations. It is also now used a lot for more decorative purposes, tables, shower doors, shelves and so forth and this is because it is safer when it breaks.

Where do you need toughened glass?

Tempered glass has been used in doors, windows, partitions and building structures since building regulations changed 1st April 2002. It is now used a lot decoratively for shower doors, tables, and shelves etc due to its safe breaking process where whole panes shatter into thousands of tiny pebbles preventing injury from sharp and jagged broken panes of glass.

Why toughened glass breaks?

If a tempered glass is struck with something sharp it can cause a notch or chip in the glass. Over time this can spread and it causes the glass to weaken and the whole pane can suddenly shatter unexpectedly. It is used for glass that covers emergency equipment as it leaves no sharp edges when broken.

What are the benefits of toughened glass?

  • It is much stronger than regular glass making it more durable and suitable for most uses
  • It is safer compared with regular glass because when broken it breaks into thousands of pebble-like cubes which drop to the floor, rather than large shards or jagged pieces of glass

What are the disadvantages of toughened glass?

  • It is more difficult to break in emergency situations
  • Complicated designs can be limited due to its manufacturing process
  • Its minimum thickness is 4mm making it unsuitable for some uses

Will toughened glass shatter?

Yes, toughened glass will shatter as a whole pane into thousands of pieces rather than crack or break in certain areas leaving dangerous sharp edges.

Can toughened glass be cut?

Tempered glass cannot be cut when it has been manufactured as it will shatter, however, it can be cut to specifications prior to the tempering process.

Does toughened glass have to have a kitemark?

The Kitemark is a service quality certification mark in the UK which is owned and operated by The British Standards Institution (BSI Group). A Kitemark is used to identify products such as glass when safety is paramount.

Is toughened glass fire rated?

Tempered glass is not fire rated and should not be used where fire resistance is also needed.

Fire Rated Glass is also known as Fire Resistant Glass and it is a specialist glass that provides protection against a fire for a certain amount of time. There is some fire-rated glass that will also provide insulation against the heat from a fire.

Is toughened glass heat resistant?

Some tempered glass can withstand temperatures of up to 243 degrees C but this will vary by manufacturer. Toughened glass is not the same as heat resistant or heat rated glass as they are manufactured and processed in a different way.

Does toughened glass shatter?

Yes, toughened glass shatters as a whole pane from wherever the break or chip occurs.

Is toughened glass breakable?

It is difficult to break toughened glass as it is 4-5 time stronger than regular glass, however, it is breakable with a certain amount of force or a chip or notch in the pane of glass can spread over time and cause it to shatter.

Can toughened glass be recycled?

Tempered glass can’t be recycled due to the chemicals used in its manufacture. The chemicals mean the glass cannot be melted in the normal recycling process.

If you are looking for Toughened Glass, Tempered Glass, Toughened Laminated Glass or any other type of glass then Toughglaze can help. We work on small and largescale development and refurbishment projects and will work alongside you to ensure the glass we produce offers a safe and design focused result. We use our state of the art production equipment, processes and facilities to produce the highest quality glass which complies to BS EN standards as listed on our Kite Mark Licence.

We have been awarded accreditations for ISO 9001: 2015 with our glazing products and processes.

Contact us today on 0208 838 4400 and one of our glass experts will be happy to help.