By Cicely Enright

Feb 04, 2022

Glass is everywhere.

“It’s in all our homes and commercial buildings; it’s in cars, electronics, and tableware. And it usually goes unnoticed unless something is wrong with it,” says Rick Wright, Oldcastle BuildingEnvelope and vice-chair of the committee on glass and glass products (C14). “It’s an extremely large part of everyday life.”

This amazing material has ancient history. According to Pliny, Phoenician merchants made the first glass around 5,000 B.C., while archeological evidence points to the first manmade glass dating back to 3,500 years ago. And obsidian arrowheads, if you count glass created by nature, were used even before then. 

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With main ingredients of sand and soda ash, there are many types of glass to choose from. “Each glass type has different chemical, mechanical, and physical properties,” states Dr. Kayla Natividad, Pilkington North America, chair of C14. “Soda-lime silica glass is the most common type of glass used today and can be found in numerous applications including architectural, automotive, and container glass. Glass that needs to resist higher temperatures, like lightbulbs, cookware, or laboratory-ware, are typically made of borosilicate glass.” 

Supporting the quality of glass is the aforementioned committee on glass and glass products, which has developed standards for the industry for decades. The committee addresses the physical and chemical properties of glass and establishes the industry standards for production and fabrication. These documents address what goes into glass, how glass acts, how glass looks, and how to measure and quantify glass properties.

Seven technical subcommittees oversee 60 standards at ASTM International. The subcommittees include:

• Nomenclature and Definitions
• Chemical Properties and Analysis
• Physical and Mechanical Properties
• Glass Containers
• Flat Glass
• Glass Decoration
• Optical Properties

With the committee’s standards, you can perform a chemical analysis of glass sand (C146) and soda-lime and borosilicate glass (C169). Or, test the internal pressure strength of glass containers (C147) and their thermal shock resistance (C149). You can even check the acid resistance of ceramic decorations on glass tableware (C676) and returnable beer/beverage containers (C735). And there’s more.

The committee’s work includes a few particularly significant standards.

The specification for flat glass (C1036): Natividad and Wright note that this is the industry standard for the quality of glass produced and sold in North America. Covering the quality requirements of flat, transparent, clear, and tinted soda-lime glass, the standard applies to mirrors, coated glass, laminated glass, and other general architectural products. From edges and squareness to allowable chips and blemishes, the standard details tolerances and tests to help define acceptable glass quality.

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Two additional standards from the committee address specific types of flat glass. These standards are cited in glazing industry and building codes for safety glazing in residential and commercial construction. 

Specification for heat-strengthened and fully tempered flat glass (C1048): This standard covers heat-treated glass used in general building construction and their requirements. Starting with the classifications of glass, this standard provides fabrication requirements of heat-treated glass, and guidance on what to include in procurement documents for products that fall within the scope.

Specification for laminated architectural flat glass (C1172): C1172 covers the quality requirements of flat laminated glass, which consists of two or more lites (pieces) of glass bonded with an interlayer material. Laminated glass is often used in applications that require additional glass retention properties for safety, security, and extreme weather or blast resistance. Like C1048, this standard also provides what information to include in procurement documents for laminated glass.