A laminated glass is an assembly composed of at least two panes of glass bonded together across their entire surface by an interlayer. For laminated safety glass, the most widely used interlayer is a plastic PVB (polyvinyl butyral) film, but EVA (ethylene vinyl acetate) films or a safety resin may also be used. In the event of breakage, the bond between the glass and the interlayer ensures that the broken pieces remain in place—at least for a certain period or up to a specified load level.
According to standard ANSI Z97.1, a laminated glass may be considered a safety glass if it meets the requirements of a specific resistance class following the pendulum impact test detailed in this standard. In some specific cases, tempered or heat-strengthened glasses are used to manufacture laminated glass. As such, in specific applications requiring a high level of compression, a laminated glass composed of tempered and heat-strengthened glass is sometimes used. The former provides mechanical strength, while the latter gives adequate residual stability if the glass breaks and cannot be immediately replaced. Heat-strengthened laminated glass is sometimes used when a higher level of wind load resistance is required than that offered by annealed float glass—as well as to prevent the risk of breakage due to thermal shock.
Glass With a Self-Adhesive Film
A self-adhesive film may be applied to a glass to keep fragments in place in the event of breakage. These films are generally used for applications such as mirrors and opaque painted glass.
Fire Rated Glass & Glazing Products
Some of the key elements in building design and renovation are light, open environment, visual safety, and communications. Virtually all of these require the use of glass. In the past, designers had limited options under the building codes. But today with so many new fire-rated glazing systems available, design freedom is at the fingertips of the creator.
North American building fire codes are built upon the concept of compartmentalization. Thus, fire-rated glazing materials are intended to help compartmentalize a fire and smoke in a building. A fire rating is determined by the length of time a product can meet fire endurance testing to either fire-protective or fire-resistive US and Canadian building standards. The fire-protective or fire-resistive ratings mandated by most major codes are based on the application requirements. These requirements depend on how much time is necessary to maintain the structural integrity of the building, property protection, and safe egress of its occupants.
Fire-rated glazing materials carry a label on the glass that may include the manufacturer, listed fire-rating, safety standards, test standards and testing agency. There are a number of fire-rated products that will meet all the necessary fire-rated building code requirements. These products are divided into fire-protective and/or fire-resistive categories.
An insulating glass unit is a glazing that is factory sealed and made up of multiple sheets of glass separated by a spacer and filled with dehydrated air and/or gas. The main purpose of double glazing or triple glazing is to provide a higher level of thermal insulation than single glazing. The thermal insulation characteristics of insulating glazing can be combined with properties such as solar control, sound insulation, and safety by using the appropriate glass products as components of insulated glazing.
High Performance Double Glazings
The development of techniques for applying metallic coatings to glass has been a decisive step forward in improving the thermal insulation of glazings. Applying a metallic coating to a glass makes it “high-performance” (also called “low-emissivity” or “low-e”).
These coatings generally fall into two different categories. Sputter coatings (“soft” coatings) are applied inside a vacuum chamber and must be positioned inside a double glazing unit. Pyrolytic coatings (“hard” coatings) are applied as part of the float manufacturing process.
In a typical dual glazing with surfaces numbered 1 through 4, low-emissivity coatings are generally applied in position 2 or 3. Placing them in position 2 does not affect their insulation properties, but rather their reflective properties—and therefore the overall solar heat gain and look of the glazing.
The first type of thermally insulating glazing was double glazing, which is composed of two sheets of glass separated by a spacer to provide a space filled with dry air. Since the air has a thermal conductivity of 0.025 W/(m.K) (at 50˚F or 10˚C), while that of glass is 1 W/(m.K), the layer of air enhances the insulating properties and reduces the U Factor of the glazing.
Spandrel panels are positioned on the exterior of commercial buildings to mask opaque sections, as well as the structural elements of facades. Used in conjunction with vision glazings, they have given rise to “curtain wall“ facades. Depending on the products and colors used, either complete harmony or contrasting effects can be achieved when specifying spandrels and vision glass. From an aesthetic point of view, choosing the ideal spandrel for a particular vision glazing is not always easy. AGC recommends that architects, specifiers, building owners, and glass professionals work together to choose the most appropriate solution, using actual glass samples and prototypes. AGC has an expert team of architectural and Technical Services consultants to support this decision-making process. Spandrels can be combined with thermal insulation, sound insulation, and fire protection functions, depending on the specific customer application.
A number of different types of spandrels are available:
- Single-pane, ceramic frit enameled glass—this is clear or colored glass that is coated with a ceramic frit and then tempered or heat strengthened
- An insulating glazing made of the same glass as vision glass (as an external glass) and spandrel glass (as an internal glass)
- An insulating glazing enameled in position 4
- A shadow-box—this is a spandrel made up of vision glazing combined with an opaque background (metal sheet, etc.) in order to produce an opaque glass section in harmony with the building
Except in special cases in which a preliminary study has been carried out, spandrels are heat strengthened or tempered. For spandrels in insulating glazing positioned in front of a structure built out of concrete or an insulating material, a thermal study is required to ascertain the glazing’s durability.
AGC's Krystal Kolours back-painted glass products offer a colorful, opaque glass appearance that is perfect for a range of decorative interior applications. By applying a high-quality paint to the back of its Krystal Klear low iron float glass, AGC creates a product that beautifully combines form with function.
Mirrors are manufactured by applying a reflective coating to a suitable substrate. The most common substrate is glass, due to its transparency, ease of fabrication, rigidity, hardness, and smooth finish. The reflective coating is protected by the glass on one side and an optional protective paint on the other. Glass mirrors are usually coated with non-toxic silver
Opaque Glass Options
Heat Treated Glass
Heat Treating is the process of heating the glass to a high temperature and then quickly cooling it to add strength by increasing the surface compression. Heat treated glass is available in two forms, tempered and heat strengthened, and should be selected based on needs of the application.
Heat Treated Options
Light Diffusing Glass
This decorative product is flat glass that undergoes surface treatment (i.e., abrasive etching at high pressures). This process can be used to obtain uniform or multi-relief motifs.
These products feature distinctive patterns added to molten glass in a special process to create stylish textures and effects with varying degrees of privacy and diffusion. When ultra-transparent glass is used as the base material, the product can achieve high light transmittance.
Screen Printed Glass
This decorative product is manufactured in a process similar to enameling. An enamel coating is applied to part of the glass using a screen and is vitrified during the tempering or strengthening process.