If you are interested in buying tempered or toughened glass, then you might be unsure on how to tell if the glass you are buying is tempered. It is a difficult task. Toughened glass and regular glass look identical, but there are many practical differences.
For example, toughened glass is up to 5 times stronger than regular glass, and it shatters into small shards if damaged (significantly safer). As a result, toughened in commercial and residential settings, where the strength of the glass is required for safety and aesthetic purposes, e.g. balconies, rooflights or balustrades.
Toughened glass is more expensive than regular glass due to the intense process it has to go through. So, you may want to check you are getting your money’s worth and that you haven’t been ripped off with regular glass. Below, we will discuss the different methods for telling if the glass is tempered.
Key takeaways
- Tempered glass is usually stamped with an identifier in the corner that shows the manufacturer and the safety standard.
- Slight imperfections, such as small bends or surface marks, can be signs of the tempering process.
- Tempered glass often has smoother edges than regular glass.
- Tempered glass cannot be drilled, as it will break into small shards.
- Scoring a line can indicate whether the glass is toughened, but this should only be done when removing the glass or by a professional.
- Key benefits of tempered glass include improved safety, durability, UV protection, and versatility for both home and commercial projects.
1. Tempered Glass Is Stamped With An Identifier
Tempered glass is stamped with an identifier, which can be found in the corner of the sheet of glass. The identifier will show the manufacturer name and the CPSC (Consumer Product Safety Commission) standards, e.g., “CPSC 16 CFR 1201 CAT II”. This proves if the glass is tempered or not. If you have purchased the glass directly from the manufacturer, then the marking will be obvious.
The tempering process to create toughened glass is intense and more costly than regular glass. This is why it is important to be able to tell if you are working with toughened glass. The process consists of heating regular glass to temperatures between 620°C and 650°C, then cooling it down with blasts of ice-cold air. This compresses the glass, making it very tough and resistant to heat damage.
This method of checking is not always reliable, as a frame may cover the marking, or fading may occur over time. We suggest pairing this method with another we have suggested if you can’t find the mark.
2. Slight Imperfections
A common mistake when identifying toughened glass is assuming that imperfections indicate the glass is not tempered. If there are slight imperfections on this glass, it may be tempered.
One common imperfection is slight bending caused by the tools used in the tempering process. Also, the glass surface might have small scratches caused by small pieces of debris that melt onto it during the heating process.
3. Smooth Edges
One way to check whether the glass is tempered is to inspect the edges. Feel the edges of the glass and determine what type of glass it is.
Tempered glass has a very smooth finish due to the heating and cooling process it undergoes to become toughened. This gives the edges a smooth and sleek look and feel. Whereas with regular glass, the edges are typically rough.
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4. Use Polarised Glasses To Identify Tempered Glass
Another way to tell if the glass is tempered is to put on polarised sunglasses and look at it in the sunlight. Polarised glasses block out certain types of light, which is why they are useful to use in this case.
You can tell if the glass is tempered by looking for lines stretching along the pane, created by machine rollers during the tempering process. Often, these are difficult to spot, so look carefully and take them in.
5. Tempered Glass Can’t Be Drilled (It Will Break)
There are many easier ways to check if the glass is tempered than drilling it, but it is worth noting that toughened glass can’t be drilled into, as it will break.
Tempered glass breaks into small glass shards, rather than large glass chunks like regular glass, as the glass breaks parallel rather than perpendicular. This makes toughened glass significantly safer, as the small, round shards reduce the harm and damage caused by glass breaking.
If you are looking for even safer glass, then you should check out laminated glass. Laminated glass has an extra layer between the two sheets, which prevents the glass from breaking!
6. Score a Line
Scoring a line in the glass is another way to be able to tell if the glass is tempered. However, we only advise using this technique if you are removing the glass. It should never be used on brand-new glass.
To be on the safe side, you should hire a glass professional to cut the glass. However, you can do this yourself by purchasing a window-cutting tool online or in a DIY store. You should not use a standard DIY knife for this task, as it can be extremely dangerous and inefficient.
The appearance of the line indicates whether the glass is toughened. If it is toughened glass, the line will be bumpy and uneven. But if it is regular glass, then it will be a relatively straight and clean line.
Benefits of Tempered Glass
There are many benefits to using tempered glass in your home or business. Here are just a few:
- Strength: Toughened glass is up to 5 times stronger than regular glass. This makes it more durable and safer than other options available. It is extremely hard to break.
- Safety: Tempered glass is extremely safe. It is very unlikely to break, but if it does, it shatters into safe, small pieces, which limit the damage and injuries it can cause.
- UV Protection: Another benefit is that toughened glass absorbs 65% of sunlight, which is safer and helps protect you from harmful, excessive light.
- Versatile: A great thing about toughened glass is its versatility. It can be used at home or in your business, and with many different applications in both settings. Check out TuffX’s gallery for inspiration on how you can use glass.
There are many more benefits of toughened glass; read more about these in our blog post ‘10 Benefits of Toughened Glass’.