SIC 3231

This category covers establishments primarily engaged in manufacturing glass products from purchased glass. Establishments primarily engaged in manufacturing optical lenses, except ophthalmic, are classified in SIC 3827: Optical Instruments and Lenses, and those manufacturing ophthalmic lenses are classified in SIC 3851: Ophthalmic Goods.

NAICS Code(s)

327215 (Glass Product Manufacturing Made of Purchased Glass)

Industry Snapshot

In the late 1990s, the industry was made up of 1,528 companies operating more than 1,650 establishments. These companies generated shipments valued at $11.49 billion, up roughly 45 percent from 1992 shipments of $6.89 billion and up nearly 20 percent from shipments of $9.66 billion only two years earlier in 1998. Employment in the industry, which hovered around 50,000 in the mid-1980s, has increased more modestly, reaching a total of 63,945 in 2000. Of the more than 63,900 workers employed by the industry in 2000, nearly 51,700 of them were involved in production operations. The annual payroll for all employees in the industry totaled $2.15 billion in 2000.

Organization and Structure

Firms in the purchased glass products industry are distinguished from other glass manufacturing firms—known as primary glass manufacturers—in that their products are not made directly from raw glass materials but from secondary glass bought from other companies.

Companies within the industry make everyday home glass products, such as mirrors, beverage glasses, shower doors, bathtub enclosures, picture glass, ash trays, lighting fixture glass, glass top tables, display shelving, window glass, automobile glass, clock glass, patio doors, oven door panels, novelty and souvenir glass items, appliance glass, and cosmetic and perfume containers. Industry products are also used in an extensive number of industrial, technical, and other non-household applications such as safety and bullet-proof glass, instrument dials, precision glass tubing, stained glass, industrial safety glasses and welding lenses, greenhouse glass, glass fiber used in optical components and for data and nondata transmission (faceplates, sensors, and glass-based optical coatings), chemical glassware, instrument panels, cathode ray tube screens, and high-tolerance specialty glass products such as elapsed-time indicators and gravitysensing electrolytic transducers.

Important subgroups of industry products include beverage glasses such as tumblers and stemware, beer glasses, crystal and casual glassware, and glass fiber used in optical components and for data and non-data transmission.

Product Manufacture. Because industry firms do not make glass from raw materials as do primary glass manufacturers, the methods for making glass products from purchased glass vary with the specific product. Firms within the industry buy glass in the following forms: float glass (a type of flat glass manufactured by floating the glass in a bath of molten tin), sheet glass, plate glass, glass sand, and "cullet" or glass scrap.

Other materials and supplies used in the manufacture of purchased glass products include industrial inorganic chemicals, plastic film and sheets, ground or otherwise treated nonmetallic minerals, and sodium carbonate (soda ash), as well as paperboard containers, wood boxes and pallets, and lumber.

Some of the more common glass products, which illustrate different glass manufacturing methods, include laboratory glass, laminated glass, mirror glass, ornamental glass, safety glass, and stained glass.

Laboratory Glassware. Laboratory glass products such as test tubes, beakers, vials, and glass for distilling liquids are often made of borosilicate glass (a combination of boric oxide, silica sand, and other chemicals) because it has a high natural resistance to temperature change and corrosion, making it ideal for scientific, pharmaceutical, and some household uses. A common manufacturing method for laboratory glassware is machine blowing, in which molten glass is fed into a blowing element where jets of air are blown into the liquefied glass, causing it, with the aid of molds, to expand and conform to predetermined dimensions. Another common glass making method is machine pressing, where molten glass, cut at regular intervals into individual dollops, is dropped into molds where it is then shifted beneath a plunging or pressing element that gives the glass, when cooled, its final shape.

Laminated Glass. Laminated or compound glass is comprised of two or more sheets of glass and a layer of plastic fused together by heating in a pressurized tank or autoclave. When laminated glass products such as automobile windshields are broken, they crack rather than shatter because the fragments adhere to the plastic layer, maintaining the glass' transparency and preventing the scattering of shards.

Mirror Glass. Mirrors are made by treating washed float glass with a tin-based mixture, then spraying the surface with a "silvering" solution made of silver nitrate and water, followed by a "reducing" agent. The combination of the tin solution and the reducing agent creates a reflective silver film on the glass surface, which is then treated with a layer of copper and a protective lacquer and allowed to dry.

Ornamental Glass. Ornamental glass products are made by running sheets of glass through rollers that shape or emboss the glass surface according to the specific (and often trademarked) design of the individual firm. Some types of ornamental glass, each made using different techniques, include light scattering glass, "wave" glass, lined glass, curved or semicircular "roundel" glass, and glass with flower or other decorative impressions.

Safety Glass. Safety or tempered glass is designed to break into small, rounded pieces of a predetermined size when shattered, thus reducing the creation of dangerous sharp fragments. Such glass is manufactured by heating sheets of flat glass, then subjecting them to bursts of cold air, which causes the interior of the glass to cool more slowly than the surface. The physical bond between the interior and external glass layers is such that when the pane is broken, the fragments are small, uniformly sized, and noninjurious.

Stained Glass. Stained glass consists of segments of individually colored panes joined together to create an image or pattern. The three methods for staining glass are painting, fusion with metallic oxides, and enameling. Glass painting involves applying pigments to hardened glass, then permanently burning or baking the pigment onto the surface of the glass in an oven. Alternatively, metallic oxides of varying colors can be added to glass while it is still molten, changing the tint of the glass itself when it cools. Metallic oxides are also used in enameling methods but are applied to hardened rather than molten glass. The enamel coating is then bonded with the glass by firing or baking.

Industry Specialization. Many industry firms manufacture more than one type of glass product. For example, Apogee Enterprises Inc. of Minnesota produces insulating, heat-tempered, laminated, non-glare, picture, automotive, and bullet-resistant glass. A few firms, however, such as American Mirror Company, Inc., of Virginia; Fisher Skylights, Inc., of New York; and Riordan Stained Glass Studio, of Ohio, specialize in a single line of glass products. Industry specialization in glass product manufacturing is also reflected in the names of some industry firms, such as Artistic Shower Door & Mirror Company Inc., Pilkington Aerospace Inc., National Bullet Proof Inc., and Christmas by Krebs Corporation, among others.

End-Users. The major users of glass products, including some non-industry products but excluding containers such as bottles and jars, consist of individual consumers; manufacturers, such as motor vehicle and car body; exporters; restaurants, bars, and other eating and drinking establishments; automotive repair shops and service businesses; lighting fixture and equipment manufacturers; miscellaneous plastics products manufacturers; hotels and other hospitality businesses; and electric lamp manufacturers.

Background and Development

Between 1972 and 1987, the purchased glass products industry experienced continuous solid growth, with the only declines in the value of shipments occurring in the mid-1970s. In that 16-year period, the value of industry shipments more than quadrupled from $1.3 billion to $5.4 billion, the number of industry firms increased 38 percent from 817 to 1,325, and employment grew 52 percent from 33,700 to 51,100. At the same time, the cost of materials and payroll as a percentage of total shipment value declined from 73 to 67 percent industry wide.

In the 10-year period between 1987 and 1997, the industry's shipments again showed dramatic growth, climbing 79 percent from $5.40 billion in 1987 to $9.67 in 1997. By contrast, the number of companies in the industry grew a much more modest 15.3 percent from 1,325 in 1987 to 1,528 in 1997. The cost of materials and payroll as a percentage of total shipment value inched downward from 67 percent in 1987 to 64.7 percent in 1997.

Faced with decreased demand for glass products, industry firms entered into joint ventures, introduced new products, and improved facilities in the early 1990s to stimulate sales. Between 1992 and 1994, glass container shipments averaged about 70,000 per quarter, with seasonal fluctuations.

Current Conditions

The value of industry shipments grew steadily throughout the late 1990s into 2000, increasing from $9.64 billion in 1997 to $11.49 billion in 2000. The cost of materials between 1997 and 2000 grew from $4.41 billion to $5.13 billion. Total industry employment grew roughly 5 percent over this time period.

Industry Leaders

Major players in the industry in the late 1990s included Guardian Industries Corp., Donnelly Corp., and Safelite AutoGlass Corp., all of which made automotive glass products. Guardian, headquartered in Auburn Hills, Michigan, near the North American home of DaimlerChrysler, also makes glass products for use in construction applications. Guardian's 1998 sales hit $2.2 billion, an increase of 10 percent over the previous year. Donnelly of Holland, Michigan, is the world's leading manufacturer of rearview mirrors. For fiscal 1999, the 12 months ended June 30, 1999, the company posted revenue of $905 million, an increase of 18.6 percent over the previous year. Based in Columbus, Ohio, Safelite is best known for the manufacture of automobile windshields. Safelite posted sales of $876.8 million in fiscal 1999, the 12 months ended March 31, 1999. This represented a whopping 310 percent increase over its showing the previous year.


In 2000, the industry employed 63,945 people, a significant increase compared to the 1987 workforce of 51,100. Production workers totaled 50,691 in 2000, compared to 47,475 in 1999. The industry's payroll in 2000 was $2.15 billion, of which $1.42 billion went to production workers.

The glass-making occupations with the greatest number of workers were glass product assemblers and fabricators (12 percent of glass industry employment); general helpers, laborers, and material movers (8 percent); hand packers and packagers of manufactured products (6 percent); glass manufacturing machine feeders and offbearers—workers who deliver raw materials and carry them away from glass manufacturing machines (5 percent); and blue collar worker supervisors (5 percent). The remaining two-thirds of industry employees consisted of other production workers—such as glass product cutting and slicing machine setters, operators, and tenders; precision glass product inspectors, testers, and graders; glass hand cutters and trimmers; glass furnace, kiln, or kettle operators and tenders; and glass product coating, painting, and spraying machine operators—and nonproduction administrative positions such as sales staff, general managers and executives, support and clerical staff, and industrial production managers.

Further Reading

Darnay, Arsen J. Manufacturing USA. 5th ed. Detroit: Gale Research, 1998.

United States Census Bureau. "1997 Economic Survey: Glass Product Manufacturing Made of Purchased Glass." Washington, D.C.: GPO, 1999. Available from .

——. 1994 County Business Patterns. Washington, D.C.: GPO, 1996.

——. "Statistics for Industries and Industry Groups: 2000." Annual Survey of Manufacturers. February 2002. Available from .

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