Tempered glass is famed for its toughness. From protecting your smartphones and tablets to being deployed in cookware, windows, aquariums, and shower doors, tempered glass is revered for its versatility as well. But you must have wondered, for all this renowned strength and versatility (of application), is tempered glass cheap?
Tempered glass is more expensive than annealed and standard glass and annealed glass, typically costing 25% more. Averagely, a square foot of tempered glass costs $25. But depending on how thick and big you want your tempered glass, you can get a square foot as cheap as $10 or as expensive (especially when you need customizations) as over $40 per square foot. That said, laminated glass is more expensive than tempered glass.
Let us go further by exploring why tempered glass is pricier. But before then, let us look at the two most common applications of tempered glass: screen protectors and window panes. How much do tempered glass window panes and tempered screen protectors cost?
How much do tempered glass windows cost?
Cost-wise, tempered glass windows are in the middle of acrylic and standard glasses. Laminated and acrylic glass windows are more expensive than tempered glass, while tempered glass windows are costlier than traditional glass windows.
While a square foot of traditional glass window plate could cost you anywhere from $4-$7, you can expect to spend around $18-$20 per square foot (including installation cost) for tempered glass.
Further variations come into the cost of tempered glass windows, depending on the type of the glass, the window frame, and the manufacturer.
Compared to clear tempered glass windows (typified by their signature bluish or greenish tint), the low-iron tempered glass windows are more expensive. The low-iron variant is one of the most enduring types of tempered glass windows.
Bronze tempered glass windows are cheaper than the above two and are mainly deployed for decorative functions.
How much do tempered glass screen protectors cost?
The cost of tempered glass screen protectors varies depending on the grade. There is a broad array of such screen protector grades (with varying levels of protection). This cuts across 2D,2.5D, 3D protectors…and as high as superior ratings like 9D,11D, and 6H.
A typical 9H tempered glass screen protector for an iPhone can cost around $20, while 3D tempered glass can go for $5-10.
Why is tempered glass more expensive than standard glass?
That tempered glass costs more than traditional glass is a strong statement of the superiority of tempered glass. Compared to standard glass, tempered glass is a massive upgrade on aspects like strength, safety, resilience, and even temperature tolerance.
How about I tell you more about this?
Tempered glass is stronger
Tempered glass is more robust than traditional glass. Standard glass leverages an annealing processing for its cooling. Compared to the quenching technology (which I will tell you about shortly), tempered glass deploys, annealing is slower and produces weaker glass.
These different cooling processes (tempered glass using quenching and standard glass using annealing) result in tempered glass being 400% stronger than ordinary glass.
Tempered glass is also more resistant to bending, boasting a bending strength of 120-200 N/mm2.
Tempered glass is more tolerant to impact
The surfaces of tempered glass experience compressive stress. This makes them far more tolerant to impact than traditional glass. The latter has significantly reduced internal stress.
Consequently, traditional glass is way more fragile. When tension is applied to conventional glass, the consequent crack is propagated more rapidly (at sound speed) through the glass material.
This is because the tension is centered at the crack’s tip. This forces it to disintegrate quickly, shattering into sharp pieces. The crack’s propagation speed is reduced in the case of tempered glass by the compressive stresses pulling in its surfaces.
Tempered glass is safer
Tempered glass costs more than traditional glass because the former is safer. When standard glass breaks, it shatters into large shards. These shards are hazardous, considering how jaded and sharp they could be.
It is way safer with tempered glass. When tempered glass breaks, it shatters into square shards, which are way smaller and blunter.
Tempered glass is more thermally stable
Compared to standard glass, tempered glass boasts superior thermal stability. Tempered glass can survive temperatures 3x better than traditional glass. With a tensile strength of 65 MPa, tempered glass can tolerate elevated temperatures as high as 250°C.
How does tempered glass get the strength that makes it costly?
Tempered glass is predominantly admired for its strength, and a large part of its costliness can be attributed to this advantage. Majorly, tempered glass derives its coveted strength from its thermal or chemical treatment.
When thermally treated, tempered glass is cooled via a quenching procedure. Here, the glass is passed through a tempering oven. This can be done in continuous feed or in batches.
The temperature of the glass is raised (by the oven) over 600°C. After this comes the quenching procedure proper, which is basically high-pressure cooling spanning seconds.
In this quenching procedure, the glass gets high-pressure air blasted across its surface. For best results, such air is introduced at several positions leveraging multiple nozzles.
Thanks to this specialized quenching process, the center of the glass cools slower than the outer surface. With consequent cooling of the glass center, the exterior surfaces are pulled, effectively creating compression in the external surface and tension in the center. This way, the formed glass is way harder.
Aside from the thermal treatment, there is a far less adopted treatment process that makes tempered glass strong. This is chemical tempering.
In this procedure, external compression (on the glass surface) is achieved when a spectrum of chemicals interchange ions. As said, chemical tempering is less deployed because it costs more than the thermal treating procedure.
How can you get the best value of tempered glass for your money?
Given that tempered glass doesn’t come cheap, it is crucial you only pay for premium quality tempered glass. Unfortunately, there is an increasing profusion of fake tempered glass in the market today. This is why I will share you with techniques to tell original tempered glass.
The first way is the smoothness of the edges. Unlike standard glass with notoriously sharp edges and corners, tempered glass is sanded, smoothening up the edges.
Just bear in mind, you can tell original tempered glass by investigating the glass material via polarized sunglasses. This is as simple as decking your eyes with these sunglasses and viewing the sun through the glass material in question.
Now, if the glass is genuinely tempered, distinct lines would visibly stretch through the pane. Such lines are born from the heating procedure, particularly the machine rollers that were deployed.
You can go as far as ascertaining the tempered quality of your glass by breaking it and inspecting how it breaks. Take note that taking this path means you wouldn’t be able to recover the glass when broken, especially when its intended application needed it whole.
Nonetheless, should you choose to go on with this testing technique, your glass, if tempered, shouldn’t shatter into large and sharp shards?
Instead, the glass should disintegrate into way more granular pieces. Also, the pieces shouldn’t go flying out. If tempered, it breaks into smaller squares which are relatively less piercing.
Does imperfection mean tempered glass is fake?
Commonly, imperfections on tempered glass are suggestive of such glass being fake or ordinarily annealed glass. No, imperfections on tempered glass are no red flags.
In fact, such imperfections are strongly suggestive of the premium tempered quality of the glass. Why?
When the glass was significantly heated, chances are there would be slight distortions across its surface area.
This results from when it is handled with tongs, leaving slight distortions on it. Considering that the glass at such elevated temperature can be readily workable, the tongs should leave their marks.
These imperfections, which can be significantly improved upon installation, could be in the form of slightly bent glass or scratches on the body of the tempered glass.
Is there a superior grade to tempered glass?
Yes, laminated glass beats tempered glass in specific aspects like sound management, security, and ultraviolet radiation tolerance.
Flexibility is another aspect where laminated glass lords tempered glass. A striking disadvantage of tempered glass is that once toughened, it becomes impossible to cut them again, resize them, or generally rework them.
Laminated glass doesn’t have this handicap. Just at any time, you can cut and rework laminated glass without the risk of destroying it (as in the case of tempered glass).
This doesn’t totally eliminate the beauty and appropriateness of tempered glass for your applications. Both tempered and laminated glasses are safe to use.
What is more, both types of glasses come in an admirable spectrum of sizes, tints, and thickness, giving you lots of options to pick from.
Maintaining laminated glass is just as easy as maintaining tempered glass. Nonetheless, bear in mind that laminated glass is more expensive than tempered glass.