Glass – Exceptionally Versatile

Heat-Treated Glass

There are two different types of heat-treatment processes that can be done to annealed (untreated) float glass to increase strength of glass and provide safety based on project application, heat-strengthening and tempering. Heat-strengthening of glass involves heating the glass to approximately 1,200 degrees Fahrenheit, then force-cooling the glass slowly to create a surface compression of 3,500-7,000 psi with no minimum requirement for edge compression per ASTM C1048. This is twice as strong as annealed glass to achieve higher wind or thermal stress loads, and allows for a larger break pattern than that of fully tempered glass. Heat-strengthened glass is NOT considered safety glass by building codes, unless it was used in a laminated glass application. Fully tempered glass is heated to the same temperature as heat-strengthened glass, but it is cooled much faster with increased line speed and more volume during the air-quench. The process creates a surface compression of at least 10,000 psi and an edge compression of not less than 9,700 psi per ASTM C1048. This is designated as safety glazing as the glass would break into much smaller pieces called “dice”. Fully tempered glass is four to five times stronger than annealed glass to achieve greater spans at higher loading levels, but there is more risk of fallout when broken than there is with heat-strengthened glass, unless laminated. We recommend full heat soaking of all tempered glass (not statistical heat soaking) to lower the risk of spontaneous breakage due to nickel sulphide inclusions. There is a  statistical probability of breakage in service if not heat soak tested to European Standard BS EN 14179-1:2016 as these impurities can’t be detected with the human eye until a break occurs. 

All heat-treated glass (both heat-strengthened and fully tempered) has the potential for optical distortion due to processing at a high temperature and cooling quickly to increase strength. That said, inherent roller-wave distortion, bow and warp, and “leopard spots” (tempering strain patterns that can be seen under polarized light, also known as anisotropy) can vary due to material, equipment and manufacturer capabilities. Also, barometric pressure, altitude, wind load, temperature and glazing pressure can all have a potential effect on visual appearance.  

Laminated Glass

Laminated Glass is a type of safety glass that is made by sandwiching a layer of polyvinyl butyral (PVB) interlayer, ionoplast structural interlayer (SentryGlas® by Kuraray, formerly known as SentryGlas Plus – SGP) or ethylene-vinyl acetate (EVA) between two or more layers of glass. This process involves the application of heat and pressure to bond the layers together, creating a single, solid piece. Laminated glass offers improved safety, security from forced entry, ballistics and blast-related threats, UV protection against fading of interior finishes and sound attenuation for better acoustics. It is commonly used in skylights, roofs, canopies, balustrades, windows and facades. Since ionoplast structural interlayer is a much stiffer interlayer than PVB or EVA, which are softer and more flexible, it allows for additional strength of the laminated glass composition by allowing for load sharing between the glass plies. It also has excellent post-breakage strength to keep the glass intact in the event of breakage, as well as better edge stability than other interlayers on exposed edge applications. For these reasons, it is often the preferred choice for structural glass fins and exposed edge canopy applications. 

Insulated Glass Units (IGUs)

Insulated Glass, often know as double glazing, consists of two or more glass panes (triple-glazing is commonly used in colder climates for better insulation) separated by a spacer(s) sealed to the glass with a primary seal of polyisobutylene (PIB) for air and water tightness and filled with a secondary seal of silicone for structural integrity to form a single unit. The space between the panes is typically filled with air or a gas such as argon or krypton to improve performance. U-value is the typical measure of heat gain or loss through glass due to thermal conductance in indoor and outdoor temperatures. The lower the U-value, the better insulation the make-up provides. A solar control Low-E coating is often used to help lower the U-value, preferably on the #2 surface to reflect heat back inside the building in winter and keep heat out in hotter spring/summer months. The Solar Heat Gain Coefficient (SHGC) is also an important measure regarding insulated glass units. Solar heat gain is the measure of how much of the sun’s heat comes through the window. It ranges from 0 to 1. The lower the SHGC value, the better the Low-E coated make-up performs for solar control in keeping heat out. In addition, these coatings provide shading and glare control for occupants as well. Insulated glass units keep buildings more comfortable, quieter and energy efficient.  

Insulating Laminated Glass Units 

Insulating Laminated Glass Units combine the benefits of both energy-efficient insulating glass with the safety and acoustics of laminated glass. Adding a laminated glass lite utilizing a PVB or ionoplast interlayer (SentryGlas® by Kuraray) helps improve safety for fallout resistance in overhead glazing applications, forced-entry resistance, and in some cases, ballistics and blast-resistance (subject to analysis by a qualified engineer for determination of project-specific make-ups based on threat level required). UV-Resistance, to help reduce fading of interior finishes, is also a benefit of incorporating a laminated glass lite into the unit. Adding an ionoplast laminated glass lite (or multiple laminated lites) to the make-up also increases structural properties to achieve larger and wider spans of glazing to lower deflection due to the increased strength. 

Acid–Etched Glass 

Acid-Etched glass is a type of decorative glass that has been treated with hydrofluoric acid or other chemical etching agents to create a frosted, translucent appearance. The acid is applied directly to the surface of the glass, which results in a smooth, satin-like finish which is smudge and fingerprint-resistant, making it very useful in high-traffic areas. Acid-etched glass also offers privacy, light diffusion and aesthetic appeal. It is often used as office partitions, interior doors, shower enclosures, balustrades and furniture elements. It can also be incorporated into structural glass make-ups for decorative features and signage. 

Multi-ply Insulated Laminated Glass Units 

Multi-ply Insulated Laminated Glass is an insulated laminated glass made up of two or more layers of glass and interlayers to improve the structural and acoustical performance of the glass. It is used in many of the same applications as laminated or insulated glass, but can achieve much greater spans from 10-foot to 60-foot tall, unsupported free-span. Please consult with W&W on these types of applications to design a system to meet your specific project requirements. 

Silk-Screened Ceramic Fritted Glass 

Silk-Screened Ceramic Fritted Glass is a type of architectural glass that has been coated with a ceramic enamel frit material comprised of ground glass mixed with inorganic paint pigments to produce a color. This coating is applied to the glass surface through a silk-screen to achieve a desired pattern and then fused onto the glass through a high-temperature heat treatment process. It offers aesthetic flexibility, UV protection, glare control, energy efficiency, privacy and shading. It is highly durable, easy to clean and maintain, and resistant to environmental factors, making it well-suited for exterior applications. It is most often used inside insulating glass or laminated glass, but more recently it has been warranted by some manufacturers on the outermost surfaces. Silk-screened glass is commonly used in building facades, curtain walls, windows, canopies and interior partitions, where its aesthetic and functional properties can be leveraged to enhance the architectural design. Silk-screening is best used for single color, repetitive patterns in lines, dots or holes (mesh). 

Digitally–Printed Fritted Glass  

Digitally-Printed Fritted Glass is a decorative glass that involves the application of images, patterns or designs onto the surface of the glass using digital printing technology. This process allows for more highly detailed and customized graphics than silk-screening. The digital printing ceramic enamel is applied to glass panels and baked on, adding a unique, customized aesthetic dimension to interior and exterior spaces. Digital printing can achieve smooth gradient transition prints, as well as “double-printed” patterns on the same surface where one lighter colored ink is applied first and a darker ink is applied on top. This creates a different look from the exterior than from the interior to the outside. Digitally-printed fritted glass can be combined in insulated and laminated applications. 

Solar Control Low-E Coated Glass

Solar Control Low-E Coated Glass is an architectural glass that is designed to minimize the amount of ultraviolet and infrared light that passes through the glass while allowing visible light to enter, thereby helping to control solar heat gain and improve energy efficiency in buildings. Despite its solar control properties, Low-E coated glass still allows natural light to pass through, maximizing daylighting and reducing the reliance on artificial lighting during the day. This can contribute to a more pleasant and productive indoor environment while further reducing energy usage. It is commonly used in the construction of energy-efficient and sustainable buildings. There is a wide range of solar control Low-E products in the market depending on energy efficiency, reflectance level, color and visible light required. Please consult W&W Glass for more information to help with Low-E coating selection for your project. 

Low-Iron, Mid-Iron, Clear and Tinted Glass Substrates 

Low-iron, Mid-Iron, Clear and Tinted float glass substrates are suitable for a wide range of architectural design applications. Low-Iron glass (made with either low-iron content sand or bleached sand) offers ultimate transparency, making it a popular choice for projects that require both functional and visually appealing structural glazing solutions. Mid-Iron glass maintains a high degree of clarity but affords some cost savings due to it having a slight neutral color in the substrate. Clear glass has a light green color and is a typical glazing material that is readily stocked. When Clear glass is built-up over multiple layers in a laminated glass fin or thick make-up, however, the green color becomes more pronounced. Tinted substrates in bronze, grey, green, aquamarine, and blue can be available, but are often limited to thicknesses of 3/8” (10mm) or less, and are not regularly run products. There are solar control Low-E coatings that can be applied onto or in combination with all of these glass types in make-ups to improve energy performance as well. All products can be heat-strengthened or fully tempered and heat soaked to work in structural glazing applications. 

Bird-Friendly Glass 

“Bird-Friendly” glazing material is defined by The American Bird Conservatory (ABC) as a glazing product having a threat factor less than or equal to 30, corresponding to a conservative estimated reduction of collisions of at least 50% under real world conditions. Factors involve tunnel testing to help determine the index value. There are many considerations that go into the reduction in collisions and the threat factor assigned such as reflectivity, color, pattern spacing, pattern type, viewing angles, surrounding conditions, lighting, etc. Specimen Performance Index (SPI) or a material and Threat Factor (TF) DO NOT GUARANTEE the actual percent reduction in collisions to be expected when a product is installed on a building. There are recommendations based on research that visual markers (1/4″ (6mm) wide lines, 1/4″ (6mm) diameter dots, or shape patterns) spaced 2” (50mm) x 2” (50mm) apart horizontally and vertically (edge to edge) across the glazing do help in reducing collisions when applied to the exterior surface or #2 surface forward of any solar control Low-E coatings as visual indicators. The maximum reflectivity of a product to be considered for “bird-friendly” testing is generally less than 15% exterior reflectivity unless there is a first surface, approved visual marker pattern included. For a pattern to be effective it must be able to be seen by the bird from a distance of 9’9 ½” (3m), as that is the standard viewing distance for a bird to be able to perceive the marking and change course. New York City had adopted Local Law 15 of 2020 for Bird-Friendly Building Design as of January 10, 2021 that requires any new buildings and alterations that replace all exterior glazing of a building to comply with the following and achieve a TF of 25 or lower rating. Read the Bird Friendly Building Design & Construction Requirements.

Some “bird-friendly” visual indicator products in the market that can be applied to the first or second surface of glass products in various patterns are acid-etch, opaque or simulated acid etch color enamel frits and laser-etching. There are also UV pattern products and interlayers, that are often less visible to the naked eye, that can be applied to glass as well to have the ability to achieve bird-friendly threat factors. There are often many size and thickness limitations depending on the product and fabricator. We would advise you to speak with a W&W Glass representative to discuss your specific project needs to help with selection alternatives.