PPG Industries, Inc.

Company address

One PPG Place
15272 PA
United States


PPG is the first and only glass manufacturer in the United States to earn CRADLE to CRADLE® Certification for its entire line of high performance architectural glass products, which signals PPG’s commitment to environmental stewardship and is a benchmark of our dedication to developing and enhancing sustainable products.

PPG Flat Glass is a leading manufacturer of glass that is fabricated into products primarily for the commercial construction and residential market segments, as well as the appliance, mirror, solar power and transportation industries.


Key Operations

PPG Flat Glass manufacturing sites and glass fabrication facilities in North America:

Manufacturing Facilities

  • Carlisle, Pennsylvania
  • Fresno, California
  • Wichita Falls, Texas

Glass Fabrication

  • Salem, Oregon
  • Calgary, Alberta, Canada
  • Halifax, Nova Scotia, Canada
  • Barrie, Ontario, Canada
  • Winnipeg, Manitoba, Canada

Key Facts

  • PPG Flat Glass products include: SOLARBAN® Solar Control Low-E Glass; SUNGATE® Passive Low-E Glass; CLARVISTA® Shower Glass; Spectrally Selective Tinted Glass; Performance Tinted Glass; STARPHIRE® Ultra-Clear Glass; Subtly Reflective, Color-Enriched Glass; Reflective Glass; INTERCEPT® Warm-Edge Spacer System; SOLARPHIRE® Solar Glass Products
  • PPG pioneered low-e glass coatings in the 1980s and has spent decades refining its low-e glass products. In fact, PPG holds more patents than any other manufacturer in the glass industry.
  • Introduced in 1992, PPG's Intercept “Warm-Edge” Spacers have become the industry’s most trusted and proven spacer system, used on more than 600 million windows in North America.

Clarvista, Intercept, Solarban, Solarphire, Sunclean and Sungate are registered trademarks of PPG Industries Ohio, Inc.
Cradle to Cradle is a registered trademark mark of MBDC, LLC.


Low-e Glass
Blending Natural Views with Solar Efficiency

Glass is one of the most popular and versatile building materials used today, and it provides a dramatic aesthetic. But the beauty of glass is pointless if the people inside the building are uncomfortable or if energy inefficiency makes the building too expensive to operate.
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Low-emissivity (low-e) glass coatings were developed to minimize the amount of ultraviolet and infrared light that can pass through glass without compromising the amount of visible light that is transmitted. A microscopically thin transparent coating allows low-e glass to reflect exterior heat in warm temperatures and hold in heat during cold temperatures, making buildings light, bright and energy-efficient.

PPG offers two types of low-e coated glasses: Solarban® solar control low-e glasses and Sungate® passive low-e glass.


SOLARBAN® Solar Control Low-E Glasses by PPG

Solarban glass is a spectrally selective glass option which reduces long (ultraviolet) and short wave (infrared) radiation, while at the same time allowing visible light to be transmitted through the glass. Solarban glass products by PPG let you specify larger spans of glass that maximize natural daylighting without sacrificing thermal efficiency.

With a range of options, the Solarban family of glass products features a clear aesthetic and among the highest light-to-solar gain (LSG) ratios in the industry and can be combined with tints for even better performance. 


SUNGATE® Passive Low-E Glass by PPG

With its ability to transmit the warming rays of the sun, Sungate passive low-e glass offers the perfect balance of energy efficiency and interior comfort for heating-dominated climates because it improves thermal performance and reduces solar heat gain.  Since the coatings are neutral, Sungate 400 glass is the ideal solution for energy-efficient commercial structures where the original appearance of the glass is desired. 


The ultimate in ultra-clear low iron glass technology
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Heavy Glass

The clearest—and thickest—glass on the market

STARPHIRE Ultra-Clear Glass™ by PPG can transform your heavy glass applications from attractive to sensational by adding sparkling clarity and unsurpassed color fidelity compared to standard clear glass.  PPG makes Starphire® glass in a variety of thicknesses from ¼-inch (6mm) up to ¾-inch (19mm). With its signature blue edge, STARPHIRE Ultra-Clear Glass™ is the ideal choice for a wide range of extra-heavy glass applications, including:

Entrances and Storefronts

STARPHIRE Ultra-Clear Glass™ provides an entrance glazing option that redefines elegance brilliantly. It is the ideal solution to make your entrance or storefront sparkle and let the true colors of products, displays and logos shine through.  Lobbies and reception areas become breathtaking with the uncommon brightness of Starphire® glass. And Starphire® glass doors set a new standard thanks to their jewel-like clarity and sparkling blue edges.

STARPHIRE Ultra-Clear Glass™ provides maximum brightness for entryways with 7 percent higher visible light transmittance (VLT) than ordinary clear glass (in ½-inch glass thickness). Its amazing clarity and color fidelity show products as they really are without the greening and distortion of conventional clear glass, particularly as thickness increases.  And because of its absence of color, Starphire® glass can be laminated in multiple layers and thicknesses to provide strength and protection for applications such as jewelry storefronts.

Learn more

For more details, please review the STARPHIRE Ultra-Clear Glass Entrance Glazings and Extra-Heavy Starphire® Glass product information sheets.  For performance data, please review the PPG Monolithic Glass Comparison Data Sheet.

Safety and Security Glass

Heavy STARPHIRE Ultra-Clear Glass™ provides a new level of visual quality to safety and security glazing applications. Special building projects, such as zoo enclosures, fish tanks, jewelry display cases, protective windows and museum cases, present design challenges that are typically solved by using multi-layer laminates. That solution, however, prevents objects from being seen in their true colors, as they are distorted by the “greening” that occurs with increased thicknesses of conventional clear glass.

Starphire® safety and security glass provides 16 percent higher visible light transmittance (VLT) than ordinary clear glass in a 13/8-inch laminated glass construction, so you get superior clarity that also conceals the actual thickness of the glass.  And it can be fabricated easily to your exact specifications. Let Starphire® glass bring unparalleled color transmission, clarity and security to your next project.

Learn more

For more details, please review the Starphire® glass Safety & Security Glazings product information sheet. For performance data, please review the PPG Monolithic Glass Comparison Data Sheet.


Exterior Float Glass

Brilliant, clear building façades

STARPHIRE Ultra-Clear Glass™ by PPG provides an unprecedented option for curtainwall glass applications, offering brilliant clarity and true-to-life views of the outdoors that conventional glass simply can’t match. 

Spiderwalls and Skylights

When your design calls for maximized transmission of natural light, Starphire® glass has no equal. Offering maximized transparency with 7 percent higher visible light transmittance (VLT) than conventional clear glass in a typical skylight or spiderwall, Starphire glass provides sparkling clarity and undistorted transmission of color.

From art galleries to convention centers, corporate office buildings to shopping malls, when you want to bring the beauty and brightness of the outdoors into your interior, skylights and spiderwalls made with Starphire glass are clearly remarkable.

Learn more.

For more details, please review the Starphire® glass Skylite Glazings information sheet.  

For performance data, please review the PPG Monolithic Glass Comparison Data Sheet.

Vision Glazing

To maximize visible light transmission (VLT) and provide unfettered views of the world outdoors, Starphire® glass brings an uncommon brightness, clarity and color fidelity that no other commercial glazing product can match.  

For vision glazings in which enhanced energy performance is required, Starphire® glass can be combined with other glass coatings to satisfy energy requirements while maintaining its unique ultra-clear visual character, free of the green cast inherent in ordinary clear float glass.

To boost VLT, combine STARPHIRE Ultra-Clear Glass™ with solar control low-e coatings, such as Solarban® 70XL, Solarban® 60 or Solarban® 67 glasses.  To increase the solar heat gain coefficient (SHGC), combine STARPHIRE Ultra-Clear Glass™ with passive solar coatings, such as Solarban R100 or Solarban z75/z50 glasses. 

STARPHIRE Ultra-Clear Glass™ maintains its remarkable clarity in thickness from 2.5mm to 19mm and is stocked regionally to ensure consistent supply reliability.

Learn more

For more details, please review the Starphire® glass Vision Glazings product information sheet. For performance data, please review the PPG Monolithic Glass Comparison Data Sheet.

Spandrel Glass

Architects have never had a more beautiful way to conceal the electrical and mechanical areas between floors than with STARPHIRE Ultra-Clear Glass™.  Its brilliant clarity and absence of greening combine to offer spectacular views and true colors, enabling whites, reds and yellows to be seen with remarkable fidelity.

PPG Architectural Glass is a marketing alliance partner with ICD High Performance Coatings, the industry leader in spandrel glass coatings and manufacturer of OPACI-COAT-300®, a line of high-performance spandrel glass coatings in a range of colors and metallic finishes.

When these water-based coatings are combined with Starphire® glass in a spandrel glass unit, they offer a vivid palette of spandrel glass solutions with unparalleled brightness and color fidelity.

Learn more

For more details, please review the Starphire® glass Spandrel Glass product information sheet.


Low Iron Interior Glass

For sparkling clarity and brilliant interior views, no other low iron glass delivers like STARPHIRE Ultra-Clear Glass™ by PPG. The unique Starphire® glass edge brings more light into interior spaces while offering unmatched levels of brightness, color fidelity, clarity and visual excitement.

Interior Glass

When used for shelves, showcases, tabletops, back splashes, doors, side lites, decorative panels, clerestories and partitions, STARPHIRE Ultra-Clear Glass™ provides true color fidelity while remaining crystal clear as thickness increases. Its unique blue edge imparts a luxury and sophistication conventional glass cannot match.


For balustrades, handrails and bannisters STARPHIRE Ultra-Clear Glass™ makes interiors pop with stunning transparency. PPG Architectural Glass is a marketing alliance partner with Walker Glass in offering the Walker Textures line of acid-etched glass and mirrors made with STARPHIRE Ultra-Clear Glass™

Starphire® glass is ideal for use with acid-etched glass products because of its clarity and color fidelity, which create spectacular dividing walls, wall coverings, office partitions, show and bath enclosures, doors and display shelving, and can be used in other interior applications.

In addition to its amazing clarity, Starphire® glass’s jewel-like blue edge has a distinct advantage over conventional glass, which displays a distorting greenish cast as the thickness increases.

Bath Enclosures

Because of its supreme clarity, STARPHIRE Ultra-Clear Glass™ by PPG is the perfect choice for shower and bathtub enclosures using ClarvistaTM glass by PPG. Clarvista glass is a factory-fused, transparent coating that protects new shower glass against dullness caused over time by the corrosive effects of heat and humidity. Starphire glass' distinctive blue edge provides a luxurious aesthetic to any bathroom. 

Learn more

To see how STARPHIRE Ultra-Clear Glass™ maintains edge clarity and a beautiful aesthetic as the glass gets thicker and longer, download the new edge color guide

Performance Tinted Glass
Blue & Green Tinted Glasses

Gray & Bronze Tinted Glasses
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Blue & Green Tinted Glasses from PPG


Control solar heat gain with style

Rich-blue Pacifica glass is part of PPG’s collection of nautically inspired tints and can be combined with reflective Solarcool® or subtly reflective color-enriched Vistacool® coatings. Combined with Solarban® 70XL solar control low-e glass in a 1-inch insulating glass unit (IGU), Pacifica glass can reach a solar heat gain coefficient (SHGC) of 0.18 with a visible light transmittance (VLT) of 30 percent, which produces a light-to-solar gain (LSG) ratio of 1.63.
Click to review the Pacifica glass product data sheet for detailed performance data.

To see if Pacifica glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.


Spectrally selective glass with excellent daylighting

Atlantica glass is one of the original tints featured in PPG’s collection of nautically inspired tinted architectural glasses. As a spectrally selective glass, Atlantica glass can help you minimize reliance on artificial cooling and lighting by combining high visible light transmittance (VLT) with excellent solar heat control in a pleasant emerald-green aesthetic that complements a diverse range of building materials.

Click to review the Atlantica glass product data sheet for detailed performance data.

To see if Atlantica glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.


Blends with other materials while controlling solar heat gain

Azuria glass is a stunning aqua-blue glass that is part of the nautically inspired tinted architectural glass collection by PPG. Azuria glass’s distinctive aesthetic blends brilliantly with the surrounding environment, adding beauty while delivering solar control and spectrally selective properties that makes it one of the top glasses in the industry.

For detailed performance data, please review the Azuria glass product data sheet.

To see if Azuria glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.


Superior spectrally selective performance

Solexia glass is a soothing, light-green tinted glass that is part of the nautically inspired collection by PPG. Trusted by architects since 1952, Solexia glass remains an industry standard for spectrally selective performance.

For detailed performance data, please review the Solexia glass product data sheet.

To see if Solexia glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.


Commercial window tint without film

Part of PPG’s earth-inspired collection, Solarblue glass features a sparkling, light, sky-blue appearance that balances high visible light transmittance of 50 percent and an solar heat gain coefficient of 0.49 in a 1-inch IGU.

For detailed performance data, please review the Solarblue Glass product data sheet.

To see if PPG’s Solarblue high-performance glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.


Gray & Bronze Tinted Glasses by PPG

New Ultra-Neutral OPTIGRAY® Glass by PPG

Glass that combines a warm, neutral aesthetic with advanced solar control

Optigray glass, the newest addition to PPG’s collection of neutral tinted glasses, is designed to eliminate the green cast typically found in conventional clear glass formulations.  It produces a warm, ultra-neutral aesthetic that brings crispness to vision glazing. 

Specially formulated to function as a substrate with solar control low-e coatings, Optigray glass delivers advanced solar performance.  When paired with solar control low-e glasses such as Solarban® 70XL, Solarban 67, Solarban 60 and Solarban R100 glasses by PPG. Optigray glass produces light-to-solar gain (LSG) ratios of up to 1.96, with visible light transmission (VLT) between 29 percent and 50 percent, depending on which Solarban glass is specified.

With a subtle light-gray tint, Optigray glass balances light transmittance and solar control to offer superior performance combined with a beautiful aesthetic. 

For detailed performance data, please review the Optigray glass product data sheet.

To see if Optigray glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.


Commercial window tint without film

Solargray glass has been a popular choice for commercial structures because of its cool, light-gray appearance and ability to control solar heat gain and glare. In a 1-inch insulating glass unit (IGU), Solargray glass provides visual light transmittance (VLT) of 40 percent. Solargray glass may also be combined with Sungate® 400 glass in a 1-inch IGU for improved solar heat gain performance and lower U-values. Solargray glass's light-gray color makes it an attractive choice in combination with almost any other exterior cladding material.

For detailed performance data, please review the Solargray glass product data sheet.

To see if Solargray glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.


Privacy glass with a punch

With its bold, almost-black look, Graylite II glass is the solution for applications requiring reduced solar heat gain and a specific aesthetic objective. Graylite II glass combines superior heat-load reduction and solar control with a distinctive color contrast. Its shading coefficient is among the lowest of any uncoated glass: 0.35 for a 1-inch IGU. Daylight transmittance is 8 percent, making it ideal for glare control and privacy glazing.

For detailed performance data, please review the Graylite II glass product data sheet.

To see if PPG’s Graylite II high-performance glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.


A proven high-performance bronze glass

Solarbronze glass has been a staple in PPG’s architectural glass offerings since the 1960s because it creates a bold visual statement while maintaining energy efficiency and occupant comfort. A popular choice for commercial structures, Solarbronze glass has a warm bronze tint that adds subtle richness to the exterior and a warm glow to interior décor. The bronze color especially complements brick and stone facades.

In a 1-inch IGU, Solarbronze glass provides a visual light transmittance (VLT) of 47 percent. For even better performance, combine Solarbronze glass with Sungate 400 glass in a 1-inch IGU to improve solar heat gain performance and lower U-values. To achieve spectrally selective glass, as recommended by the U.S. Department of Energy, team Solarbronze glass with Solarban® 60 solar control low-e glass to earn a light-to-solar gain (LSG) ratio of 1.25 or better.

For detailed performance data, please review the Solarbronze glass product data sheet.

To see if Solarbronze glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW.

Reflective Glass
Reflecting beauty and performance with: VISTACOOL® Subtly Reflective, Color-Enriched Glasses & SOLARCOOL® Reflective Glasses
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Softly reflective with rich color

Vistacool subtly reflective color-enriched glasses transmit generous levels of visible light and provides color neutrality, which amplifies and enriches the tint of the glass substrate underneath without a mirror-like appearance. More understated than traditional reflective glass, Vistacool glasses are available in two distinct tints—aqua-blue Azuria® and rich-blue Pacifica®.  Vistacool glasses can be combined with Solarban® solar control low-e glass or Sungate® 400 low-e glass to achieve light-to-solar gain ratios of as high as 1.66.

For detailed performance data, please review the Reflective glass product data sheet.

To see if Vistacool glass meets the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW



The Solarcool family of reflective coated glass was introduced in 1972 and, for more than 40 years, has enhanced the appearance of thousands of buildings and the comfort of millions of their inhabitants. 

Solarcool glasses can be glazed with the reflective coating positioned on either the first or second surface. The glass has improved performance and higher exterior visible-reflectivity with a metallic sheen when installed with the coating on the first surface. Combined in a 1-inch insulating glass unit with clear glass, Solarcool glasses offer an expansive palette of appearance and performance options with solar heat gain coefficients (SHGCs) ranging from 0.34 to 0.14 and exterior reflectance of up to 37 percent.

When installed with the coating on the second surface, the glass has lower exterior visible reflectivity and maintains the substrate glass color. Combine Solarcool glasses with PPG tinted glasses, such as Solargray®, Solarbronze®, Solexia®, Solarblue®, Azuria® or Pacifica®, to produce an even greater range of aesthetic options. 

For detailed performance data, please review the Reflective Glass product data sheet.

To see if Solarcool glasses meet the aesthetic and performance needs for your next project, visit the PPG Glass eVIEW

Specialty Glass and Alliance Partners
Exceptional specialty glass for your special applications: Acid-Etched Glass, High Performance Electrochromic Glass, Spandrel Glass, Renovate by Berkowitz (Renovate), Heat-Treated Glass
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Acid-Etched Glass

Acid-etched glass products are typically used for dividing walls, wall coverings, office partitions, show and bath enclosures, doors, display shelving and other interior applications. Starphire® ultra-clear glass by PPG is ideal for acid-etched applications because of its clarity and color fidelity.

PPG Architectural Glass has formed a marketing alliance with Walker Glass Co., Ltd., of Montreal, Canada, to jointly market the Walker Textures line of acid-etched glass and mirrors made with Starphire ultra-clear glass.


High Performance Electrochromic Glass

A dynamic, 21st century glazing solution

PPG has established an Alliance Partnership with SageGlass® in Faribault, Minnesota, which produces state-of-the-art electrochromic glass that makes it easier than ever for architects to design sustainable, visually compelling and comfortable buildings with exceptional energy efficiency.

Dynamic SageGlass is a complete sun management system which optimizes daylight admission,controls sunlight glare, and provides occupant thermal comfort, an at all times preserves the view to the outdoors—offering building owners, glazing contractors and architects a cutting edge glazing package for the 21st century and beyond. Additionally, SageGlass is available in clear, blue, green, gray, and bronze to harmonize with a range of adjacent curtain wall elements, including Solarban® 67 Solarblue® glass, Solarban® 70XL Optigray® glass and Solarban® 90 Pacifica® glass from PPG. SageGlass also is able to produce electrochromic glass in custom colors.


SageGlass LightZone®, which creates up to 3 independently controllable segments within a single pane of glass, provides architects with a daylighting tool that creates the optimum balance between daylight admission, energy performance, light quality and glare management. This is an essential design element for electrochromic glass in window and curtain wall applications where large lites of glass can be used without needing to add mullions.

How Electrochromic Glass Works

The SageGlass coating is located on the cavity facing side of the exterior lite of the insulating glass unit. By applying small amounts of electricity, the SageGlass coating darkens, absorbing more of the sun’s heat and light. The SageGlass coating, which also has low emissivity (low-e), causes the absorbed energy to re-radiate from the exterior surface of the insulating glass, resulting in an unsurpassed solar heat gain coefficient of 0.09 when fully tinted with a visible light transmission of 1%. Reversing the voltage polarity returns the glass to its clear state.

Dynamic, yet controllable

SageGlass is operated through a user-friendly control system that can be customized to fit the specific needs of your project. SageGlass is automatically controlled to optimize daylighting, glare control and energy performance yet it also allows for manual overrides and can also be integrated into the building management system to allow building level control.

Applications & Benefits

Electrochromic glass is ideal for a range of building applications, particularly owner-occupied buildings such as commercial offices, education, healthcare, government and cultural institutions - anywhere that dynamic heat and light control are needed. The ability to use more glass without compromising energy efficiency and to modulate the amount of daylight admission to prevent over-lighting, in combination with the enhanced color aesthetics of SageGlass make this dynamic glazing system a high performance architectural daylighting solution.

SageGlass provides exceptional performance, providing the ideal balance of light admission and heat control to reduce energy costs and keep occupants comfortable.

The SageGlass innovative technology achieves a full package of performance benefits, including:

  • Excellent glare control while still bringing in daylight, managing heat effectively and preserving the views to the outdoors
  • Eliminating the need for motorized shades, blinds, louvers and other obstructions
  • Reducing HVAC equipment size by up to 25% or enabling the use of more sustainable heating and cooling strategies such as natural ventilation, chilled beam systems, radiant heating and cooling.
  • Providing enhanced architectural freedom to design with more glass, in more complex, interesting ways, without paying an energy or comfort penalty.
  • A “wow” factor that distinguishes projects from competition

LEED Certification Credits

Together, PPG and SageGlass can help architects achieve LEED certification credits for commercial and residential projects. BuildingGreen, Inc. has vetted SageGlass as a GreenSpec®-listed product, making it an environmentally preferable product for LEED building construction, and has declared material transparency information through Declare® and HPD as needed for LEEDv4 Material and Resources credits. All PPG architectural glass products are C2C-certified at the Bronze level. Products that are Cradle to Cradle Certified™ by MBDC are eligible for potential LEED Innovation in Design credits.


Spandrel Glass

ICD High-Performance Coatings manufactures OPACI-COAT-300® spandrel glass coatings. When these colorful, water-based coatings are combined with Starphire® ultra-clear glass in a spandrel glass unit, they offer a vivid palette of spandrel glass solutions with unparalleled brightness and color fidelity. Learn more about OPACI-COAT-300 spandrel glass coatings.


Renovate by Berkowitz (Renovate)

Easy retrofit system makes buildings more energy efficient

The Solarban® family of solar control low-e glasses is part of a revolutionary window retrofitting system marketed by RENOVATE by Berkowitz (RbB).

Intended for 30- to 60-year-old commercial buildings, the Renovate system preserves a building’s exterior while offering reduced outside noise, increased security, and annual energy savings of more than 20 percent. The system also can help building owners earn tax credits, utility rebates and a minimum of four points towards LEED® certification.

The system works by adding two lites of low-e glass to a commercial building’s underperforming existing, single-pane windows, creating an energy-efficient triple-glazed insulating glass unit (IGU). Configured with a lite of Solarban 60 glass or Solarban 70XL solar control low-e glass, along with a lite of passive low-e glass, the RbB system can offer a solar heat gain coefficient of as low as 0.27, a winter U-Value of 0.15 and an R-Value of 6.67.

Because the system is applied to the existing window’s interior surface, the building remains completely enclosed during the retrofit, eliminating the time and cost of temporarily relocating a building’s occupants. In addition, the system can be installed two to three times faster and at about half the cost of a traditional window replacement project. Click here to see how it works or visit www.RbBWindow.com.


Heat-Treated Glass

Heat-treating for safety and durability

Many of the world’s most dramatic, visually breathtaking buildings involve large expanses of glass. But these  architectural masterpieces often require that the glass be heat-treated to provide durability and/or safety. There are two processes for heat-treating glass: heat-strengthening and tempering. Both processes take place on the same processing equipment and involve heating the glass to approximately 1200° F, then force-cooling it to create surface and edge compression. Which process is required depends specific application of the glass.

Tempered glass

Tempered glass, which also may be called safety glazing, is typically specified to provide security or to keep occupants safe wherever there is the potential for broken glass to hurt people if it becomes a projectile, such as in a fire, explosion, tornado or hurricane. It must be used in patio doors, entrance doors, side lites and other hazardous locations.When shattered, tempered glass breaks into thousands of small particles.  

To make tempered glass, the glass is re-heated to just below the melting point, but air-cooled (quenched) quickly, which creates higher surface compression and/or edge compression in the glass. Tempering makes the glass four to five times stronger and safer than annealed or untreated glass. As a result, tempered glass is less likely to experience a thermal break.

Heat-strengthened glass

Heat-strengthened glass is typically specified when additional strength is needed to resist wind pressure, thermal stress or both, but the strength or safety break pattern of fully tempered glass is not required.  A common use of heat-strengthened glass is in spandrel glass.

An advantage of heat-strengthened glass is that, when broken, the glass fragments are more similar in size and shape to annealed glass fragments and thus tend to stay in the opening longer than fully tempered glass particles. Although heat-strengthened glass is NOT a safety glazing by building code, this breakage pattern prevents the glass from falling and injuring someone.

To make heat-strengthened glass, the glass is reheated after forming to just below melting point and then air-cooled more slowly than tempered glass. This slower cooling forms a compressed surface which increases its strength to approximately twice as strong as annealed or untreated glass.

The industry standard specification requirements for heat-treated or tempered glasses are ASTM C1048 and ANSI Z97.1, as well as the Consumer Products Safety Commission 16 CFR section 1201. For heat-strengthened glass, the requirement is a surface compression of 3,500 to 7,500 psi with no requirement for edge compression. Fully tempered glass will have either a minimum surface compression of 69 MPa (10,000 psi) or an edge compression of not less than 67 MPa (9,700 psi).

PPG processes tempered and heat-strengthened glass at its plants in Carlislie, Pennsylvania; Wichita Falls, Texas; and Barrie, Ontario, Canada.

Effects of heat-treating glass

With both heat-strengthening and tempering, optical image distortion is a possibility. Distortion occurs in glass for many reasons, including glazing pressure, wind load, temperature and barometric pressure changes—or even changes in altitude between where a glass is made and where it is installed.

Glass distortion may also occur due to strain patterns in heat-treated glass or interference fringe patterns in the fabrication of insulating glass units. Because of its fluidity at higher temperatures, glass also is inherently susceptible to roller wave, bow and warp while it is being heat-treated.

To minimize the potential impact of glass distortion that is inherent with heat-treating processes:

  • Produce all heat-treated glass for a given project on the same equipment, using the same processing parameters
  • Use thicker glass, as it is less prone to distortion
  • Orient heat-treated glass so that roller wave [the periodic wave imparted to glass during heat-treatment, measured by the peak-to-valley distance] is parallel to the window sill/header.

Optical quality and flatness of heat-treated glass

While flatness of heat-treated glass is a factor of both how glass appears and its optical quality, other factors, such as roller wave, will weigh much more heavily. That is why there is no industry standard for flatness of heat-treated glass. 

A common specification for flatness of heat-treated glass is .005 inches (five-thousandths of an inch) or less over a 12-inch area; however, with the advent of online electronic inspection, PPG recommends specifying flatness of heat-treated glass with a formulaic calculation or millidiopter rating. 

The millidiopter rating is calculated by factoring in roll diameter and the distance, on center, between rollers to arrive at a rating expressed in a +/- tolerance.  A tolerance of +/- 120 over 90 percent of the glass surface would be an example of an aggressive flatness requirement for large commercial buildings and would narrow the pool of potential glass fabrication suppliers.


Heat-soaking is a process used to help reduce the incidence of spontaneous breakage due to rare nickel-sulfide (NiS) inclusions or fabrication damage in tempered glass before it reaches the field. It involves placing tempered glass inside a chamber and raising the temperature to approximately 550° F to accelerate nickel-sulfide expansion and cause the glass to break in the heat-soak chamber, thus reducing the risk of potential breakage in the field.

Most experts agree that heat-soaking does not guarantee 100 percent elimination of potential spontaneous breakage.  Further, the process may create other risks. Please see PPG’s Technical Document TD-138 for a more complete discussion of the topic.

Herculite® and Hestron® Heat-Treated Glasses by PPG

Herculite glass describes any glass product expertly tempered by PPG. All PPG glass is available with the Herculite brand. Only glass tempered by PPG can be identified with the exclusive Herculite brand.

Hestron glass describes any glass product expertly heat-strengthened by PPG. All PPG glass is available with the Hestron brand. Only glass heat-strengthened by PPG can be identified with the exclusive Hestron brand.

Herculite and Hestron are registered trademarks of PPG Industries Ohio, Inc.



Design with Clarvista Glass for timeless beauty.

Make the beauty of a new shower enclosure last and last with the timeless clarity of Clarvista glass. Clarvista glass provides a permanent protective coating that keeps new shower enclosures looking sparkling clear by preventing the dullness that can come from heat and humidity over time.   With Clarvista glass, new shower glass will remain beautiful for years to come.

Clarvista glass is the perfect choice for today’s seamless shower designs because it protects the clarity right from the beginning and stays clear for the lifetime of your shower glass. And it’s as functional as it is beautiful. With the durable Clarvista glass coating, you get a super-smooth, protective seal that helps your shower glass stay cleaner longer and makes it easier to clean when you need to.

Why Clarvista Glass?

If left unprotected, even the highest-quality glass can become dull and hazy after years of heat and humidity in a shower enclosure. Protect your investment by using Clarvista glass to provide supreme clarity and lasting durability.

Unlike sprayed-on coatings, the Clarvista glass coating is fused to the glass during manufacturing, sealing the glass surface with a lifetime protective barrier. So with regular maintenance, shower enclosures built with Clarvista glass will maintain their beauty and clarity for many years to come.

Read more about Clarvista glass.