You have seen the commercials and heard the rhetoric of how tempered glass is more robust than regular glass for your domestic use. But is tempered glass clear, and can it be used on doors, windows, as well as shower partitions, tabletops, or staircase handrails?

While not, the main feature of tempered glass can be clear, tinted, or reflective, depending on the finishing process. It’s not endowed with as much clarity as regular or float glass due to the tempering process where hazy, unclear distortions can appear on the surface. However, safety or toughened glass is five times stronger than ordinary glass, and it’s widely used as a safer alternative.

Tempered glass is impact and scratch resistant while being shatterproof. You can spot distinct shades and stretching lines when viewed through polarized sunglasses. Continue reading to learn what this type of glass is, whether it’s transparent or reflective, and the benefits of its use.

Is Tempered Glass Clear or Reflective?

Reflective or solar control glass is either clear or tinted glass coated with a thin layer of metal oxide. The coating, about .000003 of an inch thick, is applied to the glass during the float or initial mixing and heating process. 

Many color options are available, and reflective glass offers increased aesthetic appeal, but it’s expensive to replace. Tempered or toughened glass is made reflective for building walls, windows, doors, and other surfaces. The reflective tint can be of a grey, brown, green, or blue color.

By reducing indoor solar gain and minimizing outside glare, reflective glass allows filtered visible light in. You can increase energy saving from air conditioning with reflective glass, and this process is also done on tempered glass. Using regular glass poses a risk of harm, and toughened glass is turned into reflective tempered or laminated glass.

How Does Tempered Glass Work?

One of two safety glass kinds, tempered glass is made through extreme heating with rapid cooling to produce a tougher-than-normal material. In the manufacturing process, glass is a mixture of sand, soda ash, and lime. Such a mix is then melted through incredibly high temperatures before shaping, forming, and cooling or annealing takes place.

Heating expels air particles within the glass when baked in a 1,100° Fahrenheit industrial oven. The glass is then rapidly cooled in an annealing process, where high-pressure cold air blasts cause quick surface cooling. That results in a balanced state of external and internal tensile compressional forces.

In annealing, the glass material is cooled very slowly to toughen it, which helps remove internal stresses. It’s in this process that the differences occur between tempered and float or regular standard glass. The slower cooling process is responsible for how this type of glass breaks since it shatters into small pebbles instead of large jagged chunks that can prove dangerous.

Rapid cooling is also responsible for locking the glass’s surface in a state of compensating compression to the interior core’s high tension. Compliance with safety glazing codes dictates that each pane of tempered glass, which can’t be altered from the foundry, features a permanent mark to identify its fabricator. The logo, also called the bug, contains the type of glass and the safety standards that it meets.

Fully tempered glass is 0.236 inches or 6mm in thickness and has an edge compression of not less than 9,700 PSI, while its minimum surface compression should be 10,000 PSI. For toughened glass to be considered safety glass, its compressive stress must be above 15,000 PSI or 100 megaPascal.

What Are the Benefits of Using Tempered Glass?

Tempered glass, also known as toughened or safety glass, is scratch and impact resistant while breaking into small pieces devoid of harmful sharp edges. To further prevent injury, a pane of this clear glass also disintegrates in its entirety, but you can’t rework, reshape or cut it as it’ll form inline cracks.

Toughened glass is synonymous with safety, and its applications include buildings, vehicles glass, food service implements or utensils, and cell phone and other digital device screen covers. One definitive attribute that you’ll note with glass tempered is the smooth edges that can be green or clear in coloration.

Tempered glass resists high temperatures and, as such, is usable for creatively unique applications. These include but are not limited to;

·         Staircases, handrails, balustrades, and escalator side panels

·         Windows and doors in public places, primarily revolving or sliding ones

·         Partitions for home, office, resorts, sports stadia, and airports

·         Automobile side windows and back windshield

·         Decorative paneling, facades, and aquariums

·         Bathroom enclosures, shower doors, and skylights

Due to its brittle nature, tempered glass shatters into oval-shaped blunt pebbles when it’s broken, eliminating the danger posed by larger jagged-edged pieces. It is heat resistant, deriving this property from the thermal and chemical processes of tempering. As such, safety glass is the go-to for making oven windows and automatic coffee maker carafes. 

Vehicle windshields use laminated tempered glass-paneled between two plastic sheets. The shards, instead of disintegrating and possibly causing injury, are arrested within the film on breakage. You’ll also find this type of glass on your computer screen, diving masks, refrigerator trays, cutlery, and cookware.

How Do You Know If the Glass in Your Home Is Tempered?

Unless your home was built before 1975, the chances are that the building glass is tempered. The keyword for glass is safety, and toughened glass has become the standard for many state’s building codes. In retrospect, these are bylaws that builders must adhere to safeguard safely, general welfare, and health.

Every aspect of your house that complies should offer structural strength, stability, energy conservation, affordability, and means of egress facilities. For tempered glass, your untrained eye may see it as any glass, but there are ways to identify whether it’s toughened.

Look At the Edges

If you can access the edges of the glass in your home, you’ll notice that while other types of glass are ridged or scuffed, tempered glass has smooth edges. That’s because toughened glass goes through extra processing, and you can run your finger on the edge to ascertain the smoothness. Ant sign of roughness, when there’s no abrasion, means that the glass in your home is un-tempered.

Examine Its Bug

A pane of tempered glass will feature a bug or tiny logo that’s sandblasted or etched in one of its corners. The marking contains the maker’s name, whether the glass is tempered or not, and the consumer product safety commission or CPSC standards. In the case that this watermark is visible, as frames and such could obscure it, you’ll tell whether the glass in your home is toughened.

Seek Out the Imperfections

Tempered glass will always have bending, warping, and dimples within the glass from its impactive toughening process. Imperfections occur during extreme heating, while tongs used to handle the panes often leave impressions on the surface. If you look close enough, you’ll also identify light scratches caused by machine roller particles as leftover debris that’s dragged around during standard annealing.

See Through Polarized Shades

When the sun is shining through tempered glass, wear a pair of polarized glasses, and you’ll see stretching lines and shady, dark spots across its surface. Such lines are evidence of machine roller impression, and blotches are a stellar indicator that the glass in your home is toughened.

Score a Line

If you plan to cut the glass in your home, you can score a line across the surface with a window cutting tool. When tempered glass is scored, the results are a flaky, uneven line. I wouldn’t advise attempting to cut toughened glass without the correct implements, or an expert at hand, as you’ll only cause it to chip and crack.

Types of Tempered Glass

There are two types of tempered glass, determined by the method of manufacture, including thermal and chemical tempering. The first process involves annealed glass being rolled, heated to a transition temperature, and then rapidly cooled with forced air drafts to cool the surface.

In chemical tempering, a surface layer of about 0.1mm thickness is forced into ion-exchange compression within a molten bath of potassium nitrate. The larger by 30% potassium ions are switched with sodium on the glass surface to increase toughness. Objects that have complex shapes are often made of chemically tempered glass.

Conclusion

Standard or float glass is heated to a uniform temperature and then annealed to produce tempered glass. While pricier than regular glass, this toughened variety is easier to maintain and can be finished in various colors, tinted, made reflective, or left clear. Mandatory by some public building codes for its safety, panes of toughened glass have identity bug marks and smooth edges.

Sources

https://www.scientificamerican.com/article/how-is-tempered-glass-mad/
https://www.duluthnewstribune.com/lifestyle/3867733-home-fix-when-tempered-glass-required
https://chicagowindowguy.com/home-tips/why-you-should-use-tempered-glass-in-your-home/
https://info.glass.com/clear-tempered-glass/