Types of Glass Used in Doors and Windows

1. Patterned glass or Textured Glass  As the name suggests, patterned glass has a decorative design embossed on its surface. It could be a colorful geometric pattern, or just a plain texture. It is most useful in spaces which require privacy but also need sufficient light transmission. The texture on the glass surface prevents a clear view of the object when seen through the glass. It has its applications in conference rooms, foyers, restaurants, shower cubes, and windows. Patterned or Textured

2.  Spandrel Glass Spandrel glass is used to disguise the less aesthetically pleasing structural elements like columns, walls, shear walls, beams and so on. It comes in plenty of colors and hence can be used in versatile locations to compliment the interiors. It is opaque and reflective in nature. The uniform appearance of the Spandrel glass gives a neat look to the space. It is called spandrel mainly due to its great malleability. It can be moulded and shaped to cover even the curvature joining two spandrel columns. It is also 5 times stronger than the traditional and annealed glass. Spandrel glass also finds its applications in kitchen interiors. It can be used to cover the kitchen cabinets and walls instead of tiling. 

3. Tinted Glass Tinted glass is manufactured by adding metal oxides to float glass. While the typical colors used are bronze, gray, dark gray, green, blue, blue-green, many other colors like red, pink, purple can also be manufactured. Different metal oxides when mixed with float glass, render different colors to it. There is not much change in the elementary properties of the glass, except the the solar transmission. Due to its tint it prevents heat transmission and absorbs solar energy. This is not ideal glass if you desire to transmit light since it hinders with light transmission

4. Reflective glass. Reflective glass is a clear glass with a metallic coating which reflects heat. It is used in Eco-friendly constructions to reduce the energy consumption of the buildings. It prevents heat loss from the interior of the building and heat gain from outside the building. While the finish is usually metallic it can also be given a tinted appearance. Another advantage of using reflective glass is that it reduces the glare which is provides comfortable working environments in the office or home. The metallic finish blocks the view of the people standing in front of the installed glass. Its main application is in facade, but it does fancy some audacious architects to use it in the interiors as well.

5. Satin Glass (Privacy glass) Satin glass has satin finish as the name suggests. It is chemically treated to give the desired finish on the surface. It is a good material for decorative purposes. It can also be used as a partition wall in retail spaces or hotels where one requires privacy as it blurs the view. Due to this property it can be utilized in fabricating a door in association with another material such as wood. Satin glass is a low maintenance product as it prevents the dust from sticking on to its surface. The finger marks don’t get printed on the skin of stained glass unlike another glasses.


6. Security glass Security glass can either be laminated or toughened. Laminated glass is an engineered glass which holds its pieces together in an event of disaster. It is ideal for a coffee table top. If your counter top breaks the shattered pieces of glass will stick together. It can also be used in sensitive areas such as jewelry shops. It is so strong that it is even capable of withstanding a bullet attack. Owning to its strength architects have used this kind of glass for designing a staircase. Toughened glass is also a popular choice for table tops since it prevents cuts and injuries due to broken glass.

7.  Clear glass  Clear glass is the most common type of glass seen in interior spaces. It is colorless and has blue or green colored edge due to the presence of iron oxides. It is not as strong as laminated glass. Clear glass allows almost 80-90% of the visible light to pass through. It can be used in multiple locations in the house and for other decorative purposes. You can craft anything from a door knob to a facade to a chandelier using this type of glass. Its transmittance quality makes it an ideal material for making lamps and chandelier. It can also be molded into a clear glass vessel type wash basin or a over the counter type wash basin. 

8. Acoustic Glass As the name suggests, this type of glass has acoustic properties and thus is most suitable in areas with high noise pollution. Noise pollution is stressful and with the kind of lifestyle we are living  the level of noise pollution is rising preposterously especially in cities. The glass has a double glazed arrangement of which the inner layer damps out any belligerent noises. It absorbs and weakens noises thus reducing the decibels heard by humans. Acoustic glass finds its application in diverse spaces like office space, conference rooms, music studios, hospitals, libraries, residential houses and retail spaces.

9. Energy Efficient Glass Windows are responsible for as much as 25% of heat exchange between the interior and exterior of your house. This means choosing the right kind of glass can prevent the heat from escaping your house in winters, and hinder the heat from creeping into your interior space in the summers. It can reduce your electricity bill up to 20%. Installing this type of glass also lowers your carbon footprint which will ultimately make you feel good about yourself. Many retail shops can also enjoy the benefits of installing an energy efficient glass on their glass facade. Since the facade is exposed directly to the sun, use of environment friendly glass will reduce requirement for heating or cooling the space depending upon your geographical location. 
There are various different types of glass that are used in doors because they are strong and sturdy. Here are the main types of glass used in doors along with the benefits of using these types of glass.

 

Toughened Glass

It is a legal requirement that all replacement doors must have toughened safety glass. This is laid down in the building regulations in LA County, Ventura County, and San Fernando Valley. 

Laminated Glass

Laminated glass although also classed as safety glass reacts very differently to toughened glass.

laminate glass in shop windows

Store shop laminate window glass stays together when broken. 

Laminated glass consists of two pieces of glass with a layer of poly vinyl in-between.

laminated glass

A build up diagram of laminated glass showing the polyvinyl inter layer between two panes of glass.

The inter layer keeps the layers of glass bonded together even when broken and produces a characteristic spider web effect when the impact is not enough to completely pierce the glass.

Laminated glass is normally used when there is the possibility of human impact or if shattered glass could fall such as car windscreens or skylights.

Frosted Glass

Although all glass will be safety glass the other options available are clear or frosted.

 Doors with frosted glass option is acid etched which historically has been achieved by using corrosive hydroelectric acid. This results in the removal of some silica from the glass surface leaving a roughened, frosted appearance. The reaction is not an overly rapid one so it can easily be used to create artistic results. Acid etching can be used to create artwork on glass such as that seen on the Downham Oak internal door.

door with frosted glass

Acid etching also known as ‘French Embossing’ is a process that was invented in the Victorian era. It gives a frosted etched finish in soft tones of white and is capable of producing very intricate patterns.The process was originally used by the Victorians  for decorating the windows and doors of public houses and bars where it gave an expensive to seating areas.

frosted glass

 

Image courtesy of Tristan Forward4. 

There are multiple ways of treating glass to enhance its strength, energy efficiency, or appearance. For a detailed discussion of the code implications of safety glazing in buildings, we suggest Douglas Hansen’s article, Safety Glazing.

Float Glass

Float glass gets its name from the modern process used to create large, thin, flat panels from molten glass. The molten glass is passed onto a pool of molten tin. This process produces a very smooth piece of glass with a highly consistent thickness.

Annealed Glass

Annealed glass is a piece of float glass that has been cooled in a slow and controlled manner. This slow cooling process reduces the internal stresses within the sheet of glass so that it becomes stronger. Float glass is generally annealed and is the starting point for further treatment. Annealed glass will break into large and sharp shards or pieces. Due to safety concerns, annealed glass is rarely used in buildings.

Heat Strengthened Glass

Heat strengthened glass is made from a sheet of annealed glass that is reheated beyond its annealing point of about 1200 degrees Fahrenheit and then cooled rapidly, but not as rapidly as tempered glass. Since it isn’t cooled as quickly, the compression and tensile stresses aren’t quite equal across a section of glass. Therefore, the glass is only about twice as strong as annealed glass. Heat strengthened glass will break into smaller pieces than annealed glass, but these pieces may still be sharp and can cause injury. For this reason, heat strengthened glass is not considered to be safety glass. Heat strengthened glass is rarely used in buildings except when it is laminated.

Fully Tempered Glass

Tempering is a process that takes a piece of annealed glass and makes it four times as strong. After annealed glass is cut and finished to size (tempered glass cannot be cut), it is heated past its annealing point of about 1200 degrees Fahrenheit. Then, the glass is very rapidly cooled, which allows the internal portion of the glass to remain fluid for some time. Since the center stays fluid longer than the outer surfaces, an equal amount of tensile and compressive stresses are formed across the glass, which makes it significantly stronger. Fully tempered glass is a safety glass that will shatter into small granular pieces, which reduces the risk of injury.

Tempered glass is ideally used as a safety glass where the glazing may need to be broken out of the frame in an emergency. For instance, the side windows of a car are tempered so that they can be broken away in the event of an accident.

Heat Soaked Tempered Glass

Heat soaking is a method of testing tempered glass for unstable nickel sulfide inclusions, which are imperfections in the glass that may cause spontaneous breakage of the pane. The panes of glass are put into an oven and heated to a temperature of around 550 degrees Fahrenheit for a few hours. This causes any nickel sulfide inclusions to expand disproportionately to the glass, which makes the glass break. The idea is to force any unstable glass panes to break before they have a chance to fail in the field. This can be quite important where the glass pane is critical for safety – for instance, in a glass railing. Of course, the process increases the cost of the glass panes. It is important to note that heat soaking is not a perfect process and it will not eliminate incidences of spontaneous breakage, but it will catch most of them.

Laminated Glass

Laminated glass is made by fusing two or more layers of glass with inter-layers of polyvinyl butyral (PVB) through the use of heat and pressure. The process creates a safety glass.

If the laminated glass is made using sheets of heat strengthened glass, then the sheet of glass will break into large pieces, but it will be held in the frame by the PVB inter-layer. This provides safety, but also adds a level of security since the glass remains in place and prevents a person or object from passing through.

If the laminated glass is made using sheets of tempered glass, then the sheet will fall out of the frame, but will mostly stay together due to the PVB inter-layer. The glass looks a lot like a wet blanket when shattered.

Laminated glass is best used as a safety glass where the glazing must remain intact if it is broken – either for safety or security. For instance, the windshield of a car is laminated heat-strengthened glass so that if an object hits it, the object won’t pass through and injure an occupant nor will the glass shatter into the faces of the occupants.

Wire Glass

Wire glass is generally thought to be stronger than annealed glass; however, this is not true. Wire glass is actually less strong than annealed glass because the integrated wire disrupts the continuity of the glass structure. Wire glass is notconsidered to be safety glass.

Wire glass is most often used as a fire resistant glass because the wire holds the glass in place if it shatters due to high heat. In addition, the wire holds the broken glass in place under pressure from a fire hose. Under high temperatures, the wire holds the glass in place better than the PVB films used in laminated glass. Check out our article, Fire Rated Glass and Glazing, for more information on wired glass and other fire rated glazing.

Insulated Glass Unit (IGU)

Insulated glass units (IGU) are built-up assemblies where two pieces of glass are separated by a spacer – this is referred to as double-glazing. Triple-glazing is becoming more common and is made of three pieces of glass and two spacers. The spaces between pieces of glass can be filled with air or an inert gas, such as Argon. Argon is most common, but Xenon and Krypton are more efficient (and considerably more expensive). The sheets of glass are tempered or laminated for safety, and are generally 1/4″ thick with a 1/2″ air space. Finally, the most critical component of an IGU is the desiccant, which removes humidity from the cavity to prevent condensation within the IGU.

Double-glazed IGUs made from 1/4″ glass and a 1/2″ space filled with air have an R-value of around R-2. Changing the air to Argon gas raises the R-value to R-3. Further changing the glass to Low-E, described below, can take the assembly to an R-value of R-4. Finally, a triple-glazed IGU can have a value of R-5 or slightly higher. As always, please refer to manufacturer data for R-values of specific IGUs.

Low-Emissivity (Low-E) Glass

Low-emissivity (Low-E) glass is glass that has a special coating that reflects the infrared portions of light, while letting the visible light spectrum through. This is beneficial because the infrared heat from the sun is reflected away from the building in the summer and during the winter the infrared heat that is already inside a building is reflected back into the space.

There are two general types of Low-E coating, tin or silver. Tin oxide is applied to the glass at high temperatures to create a very hard and durable Low-E coating. The alternative is a silver coating, which must be enclosed in an IGU so that the silver doesn’t degrade over time due of oxidation.

Low-E coatings often have a slight blue-green tint, which many architects find unacceptable. Newer Low-E coatings are produced with less tint, but it is important to review product samples daylight at varying angles to fully understand what the aesthetics will be when installed.

 

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