SIC 3211

This group includes establishments primarily engaged in manufacturing flat glass. This industry also produces laminated glass, but establishments primarily engaged in manufacturing laminated glass from purchased flat glass are classified in SIC 3231: Glass Products, Made of Purchased Glass. Manufactured flat glass covered under this industry includes such types as building glass, cathedral glass, float glass, colored glass (including both cathedral and antique), insulating glass, laminated glass, optical glass, picture glass, sheet glass, structural glass, and window glass.

NAICS Code(s)

327211 (Flat Glass Manufacturing)

Industry Snapshot

The flat glass manufacturing market is dominated by products intended for use by the office and housing construction industry. In 2001, the construction market accounted for more than 50 percent of flat glass demand in the United States; the automotive industry accounted for a quarter of total demand; and the specialty glass market (mirrors, solar panels, and signs) accounted for 17 percent.

The fate of the flat glass industry, like that of most manufacturing industries, is inextricably linked to the status of the nation's general economy. Thus the industry suffered during the recessive economy of the early 2000s. Although low interest rates kept the new housing market robust, commercial and industrial construction fell off significantly. The value of U.S. flat glass product shipments has fallen consistently, from $3.5 billion in 1987 to $2.8 billion in 1998, and $2.1 billion in 2001.

As the new millennium dawned, the flat glass industry faced many challenges, including more stringent expectations for environmental responsibility and the need, shared by many industries in an age characterized by sophisticated consumers and impatient stockholders, to produce better, more technologically advanced products more cheaply. But it is also reaping benefits from a number of new technologies and new uses of glass.

Organization and Structure

Flat glass producers can be divided into two major classes: makers of raw float glass and fabricators, or companies that treat raw glass with special coatings for finished products. Two popularly used types of treated glasses are tempered and laminated flat glass. Tempered glass is discussed in more detail below; information on laminated glass and other glass products can be found in SIC 3231: Glass Products, Made of Purchased Glass.

The U.S. flat glass industry is clearly dominated by one company, PPG Industries Inc. of Pittsburgh, Pennsylvania, whose total net sales topped $7.5 billion in 1998. Other major players in the U.S. flat glass market include Minneapolis-based Apogee Enterprises and Libbey-Owens-Ford Co., an operating unit of British-based Pilkington PLC.

The distribution of flat glass once it has been manufactured and, when applicable, processed with special coatings, occurs along a multi leveled chain, with sales possible at all levels. According to Glass Magazine, the normal distribution routes for domestic and imported flat glass are directly from domestic or foreign producers to fabricators, glazing contractors, and retailers or through independent glass distributors who, in turn, serve manufacturers, fabricators, glazing contractors, and retailers. However, many companies, which may have originated as either manufacturers or distributors, have found it profitable to expand from one segment of the market into another and have integrated manufacturing, fabrication, and sales into their operations.

The flat glass industry is subject to regulation by many government agencies and branches, including but not limited to the Consumer Product Safety Commission, the Environmental Protection Agency (EPA), the Occupational Safety and Health Administration (OSHA), the National Bureau of Standards, and the Department of Commerce. Standards and recommendations for the glass industry are also set by such groups as the American National Standards Institute and the Building Officials and Code Administrators International, and more specialized groups such as the National Glass Association, the Chemical Manufacturers Association, the Glazing Industry Code Committee, and the American Architectural Manufacturers Association.

Background and Development

Archeological remains indicate that glass was first made in the form of beads or small rods in the near East (possibly Mesopotamia), beginning about 2500 B.C. Ancient glass was made from the same basic raw materials as modern glass: sand, soda, and lime, with other materials like dolomite and salt cake added. Early glass was used to make beads, vases, and other largely aesthetic objects; its fragility and limited transparency and the difficulties inherent in its production precluded other uses.

From ancient times until the beginning of the nineteenth century, glass was made by laborious hand methods. But mechanization followed on the heels of the great advances made in science and technology in that century, and this led to decreased production costs. Flat glass also became more functional, and by 1925, 42 plants in the United States were producing 600 million square feet of sheet glass.

In 1959, the English firm of Pilkington Brothers perfected the revolutionary float glass manufacturing process, which enabled flawless clear or tinted glass to be produced without the cumbersome grinding and polishing steps that had previously been necessary. The transparency of the new float glass allowed 75 to 92 percent of visible light to be transmitted to the interior of a room. The float glass manufacturing process also brought about savings: capital investment costs decreased by 25 to 50 percent per ton of glass, and manufacturing outlays decreased by 15 to 30 percent.

The energy crisis of the 1970s forced glass manufacturers to develop energy efficient glasses, like tinted and coated glasses. However, since such glasses absorb and reflect heat, they reach higher temperatures than ordinary windows. Thus, manufacturers developed tempered glass, which is heat-treated to increase its strength and ability to resist thermal stress. Tempered glass is considered safer than ordinary glass because when broken, it shatters into cube-shaped particles without jagged edges. Tempered glass is thus ideal for high-and rough-usage areas and those that come into contact with high heat, for example, storefronts, shower doors, and fireplace screens. In addition, tempered glass cannot be cut, drilled, or edged, so it is used as a security glass in the construction and motor vehicle industries. However, use of tempered glass is limited in situations where building codes require fire-resistant glazing. In 1972, demand for tempered glass was at 317 million square feet; that number rose to 1 billion square feet in 1996.

In 1983, the glass industry took energy efficiency a step further by introducing "low-emissivity" glass. "Emissivity" refers to an object's power to radiate heat, light, etc.; in the flat glass industry, the term is used to measure the ability of window glass to control energy and minimize heat loss in cold weather. The lower a product's emissivity, the more energy efficient it is. The development of low-emissivity (low-E) glass is considered the industry's greatest advance in energy efficiency since the 1970s. Low-E glass is similar to aluminum foil in that it has an invisible, colorless, thin metallic coating that reflects radiant heat and maintains cool temperatures. It is believed that the use of low-E glass in commercial buildings decreased heating, cooling, and lighting needs by as much as 40 percent.

A trend that became apparent in the 1980s was an increased use of glass walls in new construction. Designers and building owners choose to incorporate them into building design for many reasons, including their dramatic aesthetic effect and the fact that glass is cheaper per square foot than most other, comparable, building materials.

The financial success of the flat glass industry waxed and waned over the years, usually in company with the health of the U.S. economy. The industry entered a healthy growth period in 1983, which peaked in 1987, when the value of product shipments reached $3.5 billion, the highest in 15 years. The value of flat glass shipments diminished in each subsequent year until 1992, however, when only $2 billion in flat glass products were shipped.

Concurrently, the industry experienced growing prices for raw materials. In 1992, Glass Magazine reported that "the cost of materials as a percentage of the value of industry shipments rose from 31.8 percent in 1970 to 38.9 percent in 1989."

The industry's labor force also suffered during this time. In 1990, the flat glass industry employed 17,000 people; in 1992, at the height of the U.S. recession, it employed only 14,700. In fact, the trend toward a smaller workforce started much earlier than the recession. As early as the 1970s, manufacturers began actively seeking ways to further automate production processes, largely in an effort to reduce payroll costs. Their efforts resulted in a smaller glass workforce.

The recession and its effects on demand and sales levels were not the only challenges the industry faced in the 1980s and 1990s. For example, the flat glass industry's pricing methods came under scrutiny. Since the eighteenth century, it had been standard practice for glass manufacturers, distributors, and fabricators to calculate the price of total square footage by rounding up fractional amounts. However, after a glass retailer complained of unfair pricing due to this method, officials began to reexamine the flat glass industry's overall pricing methodology. Suggested alternatives included the adoption of either a unit price method or a fractional-inch computational method. Both methods require manufacturers, wholesalers, and the entire distribution chain to reprogram or recalculate glass costs to the actual fractional-inch square footage.

The industry was also rocked by a new standard proposed by the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE). ASHRAE 90.2, which was adopted in 1993, imposes limits on fenestration (the arrangement and design of windows and doors in a building) in the design of energy-efficient, low-rise residential buildings. Fenestration area is normally 20 percent of conditioned floor area in a newly constructed single family detached home, but ASHRAE 90.2 limits that amount to 15 percent. It has been estimated that the new limitation could lead to a projected 2.75 million fewer windows sold for single-family detached homes and 750,000 fewer patio doors.

The industry also faced challenges in the 1980s and 1990s on environmental, energy, and safety fronts. Several landmark legislative actions were handed down by the Environmental Protection Agency (EPA), the Department of Energy, and various local regulatory agencies. The EPA's Clean Air Act Amendments of 1990 specifically address the hazardous rate of air pollutants emitted by specific facilities and processes. The flat glass industry has been forced to find ways to manufacture high-quality glass more cleanly; some of the technological developments in this area are discussed in the "Research and Technology" section below. The costs connected with the new law and standards, which are associated with the requirements of the law itself, the steps that a manufacturer must take to obtain an EPA permit, and the penalties that can be and are levied against the law's violators, represent one of the most serious and long-lasting legacies of this period. Other environmental concerns include water pollution and waste recycling.

Laid low by the U.S. economic recession of the early 1990s, the flat glass industry struggled to recover, managing to increase shipments from slightly less than $2.1 billion in 1992 to nearly $2.7 billion in 1996. Shipments in 1997 and 1998 were projected to reach $2.7 billion and $2.8 billion, respectively.

Much promising research and product development took place during the 1990s, much of it focused on making glass windows more energy efficient. It has been found that adding gas between the sections of an insulating glass unit improves both thermal and sound control values. Heat loss by conduction occurs because of the tendency of heat to flow toward cooler temperatures. Argon gas filling in insulating glass slows the flow of building heat to the outside in winter and reduces the amount of outdoor heat entering the building.

Fire-resistant glass was another important and exciting segment of the glass market in the late 1990s. Socalled "fire-rated glazing" was expected and required to both contain fire and allow visibility for building occupants and fire fighters during a fire. Various building codes and construction standards dictate the types of buildings, as well as which areas within buildings, must be fitted with fire-rated glass. Glass fire ratings are given in terms of time (e.g., 45 minutes). In the United States, a fire rating is achieved by first subjecting a particular glass to high-temperature flames. If a rating of more than 30 minutes is sought, the glass must then be blasted with water from a fire hose. Thus, most fire-rated glass is expected to not only withstand heat but to remain intact (and thus continue to contain fire) even after being sprayed with water from a fire hose. A related concern is the ability of glass to resist heavy impact; glass that has been tested for impact resistance is called "safety-rated" glass. In many cases, builders are required to install glass that is both fire rated and safety rated.

Wired glass was the original fire-rated glass, and in 1996 wired glass continued to be the most popular type of fire-rated glass both because of its relatively low cost (at $7 to $12 per square foot, it is by far the cheapest firerated glass) and because it is the oldest and best-known fire-rated glass on the market. Most wired glass carries a fire rating of 45 minutes.

But wired glass had some limitations, such as its less than artful appearance and the fact that standards prohibit its use in sizes larger than 1,296 square feet. These have increasingly made wired glass an unattractive choice for building designers and owners seeking to use larger, clear glass windows and even walls in new construction. Two of the more promising alternatives that have gained acceptance in the 1990s are glass ceramic and transparent wall panels. Glass ceramic looks like ordinary window glass and can be manipulated like glass, but its ceramic properties enable it to easily pass both portions of the fire test with ratings up to three hours. Safety-rated versions of glass ceramic are also manufactured. A transparent wall panel is, like wired glass, fire rated and safety rated, but since it has no wire mesh reinforcement, it looks better. Because it is able to act as a barrier to heat, it can be classified as a wall, not a window, and thus it is not restricted to a limited size. Transparent wall panels are made of several laminated sheets of float glass; the lamination enables them to carry the highest levels of glass safety ratings.

The issue of window labeling exploded in the 1990s. In 1995, the Canadian Window and Door Manufacturers Association (CWDMA) began a voluntary labeling program, which sets and uses a uniform "Energy Rating" (ER) standard for windows. This standard makes it easier for consumers to compare products and for building inspectors to confirm code compliance. The Canadian market is extremely important to U.S. glass manufacturers, so the Canadian initiative helped push the National Fenestration Rating Council (NFRC) of the United States to begin developing similar window and door energy performance standards. Those efforts were still underway in early 1997, but other, distinctly nonvoluntary, labeling programs have already begun in the United States. The 1996 Building Codes include detailed and fairly complex rules on the labeling of wired and laminated glass. In some cases, the labels must be permanent; the code specifies that labels for tempered glass be either etched or ceramic fired. A February 1996 Glass Magazine article, "Building Codes Update," quoted an industry analyst saying that the new regulations were "one of the most onerous things that have happened to the glass industry."

One of the avenues for the industry's growth comes through an expansion of shipments abroad. U.S. flat glass producers have been somewhat frustrated in this arena by the tariff and nontariff barriers many countries have erected to keep out U.S. flat glass. In November 1999, Japanese government officials indicated that they saw no need to negotiate a new flat glass trade agreement with the United States. Under the 1995 flat glass accord, which expired at the end of 1999, U.S. and Japanese officials agreed to facilitate Japan's purchases of foreign-made glass. In rejecting U.S. pleas for a new glass trade agreement, Hideo Hato, director of the Ministry of International Trade and Industry's press division, told United Press International: "The market for flat glass is sufficiently deregulated and the object of the agreement has already been attained. It's not necessary to extend the '95 measures."

Senator Mike DeWine (R-Ohio), in assessing the barriers to U.S. flat glass exports, observed in early May 1999 that "American businesses face tough and often unfair competition in foreign markets that often do not have the same commitment to free and open markets that we have. I am pleased many of the issues and concerns raised during our last international antitrust hearing have been successfully resolved, but I remain disappointed Japanese flat glass manufacturers continue to engage in anti-competitive practices to limit competition. Those of us on Capitol Hill grow weary of Japan's tactics of delay and denial, and its failure to take meaningful steps to put an end to the anti-competitive scheme between manufacturers and distributors in its flat glass market."

Current Conditions

In 2001 the U.S. flat glass industry produced and shipped 6.4 billion square feet of flat glass, also measured as 5.26 million short tons. Automotive glass production totaled 1.67 billion square feet. Of that total, 45 percent was standard performance, 29 percent was high performance, and 26 percent was privacy glass. Of the 4.72 billion square feet produced for non-automotive use, clear glass less than 5 mm thick dominated the market share with 3.44 billion square feet of production.

Flat glass prices increased at an annual average of 2.1 percent in 2000 and 2001, before dropping by 0.7 percent in 2002. Overall flat glass prices are expected to remain flat—slightly higher at best—during 2003. Stagnant prices are based on a lack of demand and worldwide production capacity that can easily accommodate the market. Flat glass is expected to become more robust following an uptrend in the economy that sparks new commercial and industrial development.

Industry Leaders

The three leading U.S. flat glass manufacturers were PPG Industries Inc.; Apogee Enterprises Inc. of Minneapolis, Minnesota; and Libbey-Owens-Ford Co., an operating division of the United Kingdom's Pilkington PLC.

PPG, a flat glass and fiberglass manufacturer, is by far the overall U.S. glass industry leader. PPG sales were reported at $8 billion dollars in 2002, down 2.1 percent from the previous year. A distant second in terms of U.S. flat glass sales, Apogee Enterprises reported 2002 sales of $771.8 million, down 3.8 percent from the previous year. Pilkington PLC, the British parent of Libbey-Owens-Ford, reported total worldwide earnings of nearly $4 billion in fiscal 2002, ending March 31, 2002.


In 1979 the flat glass industry employed about 19,500 workers; by 1996 that number had fallen to 11,500. Employment remained steady into the early 2000s, totaling 11,084 in 2001. The number of production workers experienced a parallel decline, from 15,200 in 1979 to 9,300 in 1996, and 9,006 in 2001. Analysts attribute the workforce reduction to manufacturing automation and production trimming, as well as to the often mentioned recession and its effects on the flat glass industry.

Flat glass manufacturing can be difficult and dangerous work, though it is generally true that the rates of injury and work-related illness tend to be lower for companies with fewer than 50 employees and more than 100 employees than for mid-size establishments.

America and the World

Most U.S. flat glass manufacturers are engaged in some type of international commercial activity, either through joint ventures with foreign firms, licensing of technology to foreign producers, or acquisition of all or part of foreign flat glass manufacturers. The industry experienced a trend toward globalization in the 1980s. For example, in 1986, one of the major U.S. flat glass manufacturers, the Libbey-Owens-Ford Co., was bought by the British glass making giant, Pilkington, while U.S. firms like Guardian and PPG expanded by setting up factories overseas.

Major foreign players in the international flat glass industry are Asahi Glass of Japan, Pilkington of England, and Saint-Gobain of France.

Research and Technology

Computers and the Internet are causing major changes in the way that glass manufacturers, distributors, and retailers do business. Most obviously, information about glass products and manufacturing standards and specifications is increasingly available via the World Wide Web, so consumers can compare products and prices at many "stores" from home and manufacturers can access important information instantly. Plant management has also been revolutionized by new, increasingly advanced and user friendly business computing tools.

Research continues in the area of energy efficiency. While great progress has already been made in improving the ability of window glass to keep heat and sound in or out of a room, some researchers have turned their attention to the window edge, where spacer design and construction can lead to significant heat loss, decreasing overall window energy efficiency by as much as 25 percent. "Warm edge technology" is helping manufacturers to better seal window perimeters by replacing the traditional frost-prone metal window spacers with high strength, thin stainless steel, molded-in thermal breaks, and split spacers or silicone foam. This not only helps to keep the temperature of the entire window higher, but reduces the incidence of condensation and frost. Though products using warm edge technology were available in 1997, it is fair to say that the technology is still developing. It is not yet known, for example, how long existing products can be expected to last. And manufacturers are looking for a way around the facts that warm edge materials are often more expensive than standard ones and that many require an entirely new production system.

Improving low-E glass technology was considered a cutting-edge research problem in the late 1980s and early 1990s, and great strides were made in reducing emissivity. In the late 1990s, a better and more energy efficient window was still on many researchers' to-do lists, but now more demands have been added. In the May 1996 issue of Glass Digest , Day Chahroudi noted in "Smart Windows," that "it is becoming apparent that the glass industry expects its next major market expansion to come from … optical shutters, or smart windows." The technologies referred to here as "optical shutters" allow windows to perform some of the same functions as shutters or curtains—keeping sunlight out of a room, allowing it into a room, and even allowing daytime one-way viewing.

Another promising product under consideration is switchable glass, a liquid crystal glass that can be wired to any structure's electrical system and operated by flipping a switch. Liquid crystals make the glass cloudy but permit sufficient light without obstructing visibility. The electrical current changes the glass from opaque to clear. Its current use is in interior applications such as partitions and conference rooms, where privacy and optional visibility are desirable.

Tighter environmental regulations, specifically emissions standards, have brought about a significant manufacturing innovation—oxygen-fuel (oxy-fuel) combustion. According to Rich Deal, in Glass Industry, oxy-fuel offers many significant advantages over conventional combustion systems. Most crucial among these to the U.S. industry is significantly lower NOx and particulate emissions, but others include higher melt rates, reduced fuel consumption, improved workability of the resulting glass product, and the declining cost of producing on-site oxygen. Manufacturers in the late 1990s are still making the switch to oxy-fuel, and there are some real, if predictable, technological and efficiency issues still to solve.

Further Reading

Daniels, Stephen H. "Better Blast Resistance Coming Soon to Faade." ENR, 25 March 2002, 39.

Delano, Daryl. "Flat Glass Prices Refuse to Flatten." Building Design & Construction, March 2002, 20.

"Demand for Flat Glass Set to Increase." Glass International, July 2001, 3.

"Flat Glass Prices Flatter than Ever." Building Design & Construction, December 2002, 20.

"Glass Markets." Ceramic Industry, August 2001, 65.

"Glass Price Deflation Reflects Global Glut." Building Design & Construction, April 2003, 19.

Grahl, Christine L. "Flat, Specialty Glass Reflect Weak Economy." Ceramic Industry, August 2002, 37-41.

Harpole, Tom. "Shattered: Blast Tests Come Under Fire." Facilities Design & Management, October-November 2001, 60-62.

"Improvement Expected among Construction Industries, but Outlook Unfavorable for the Nonresidential Sector." Glass Magazine, 2003. Available from .

Kennedy, D. Roger. "Fragile, Soft and Tight." Glass Magazine, 2003. Available from .

McGee, Barry J. "Long-Term Outlook: Healthy." Glass Magazine, 2003. Available from .

Pilkington PLC. "Interim Results for the Six Months to 30 September 1999." Available from .

PPG Industries Inc. "PPG Reports on 3rd Quarter; Posts $57 Million in Charges," 1999. Available from .

Werbowy, Ken. "Look Deep Within for Cost Effectiveness." Glass Magazine, 2003. Available from .

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