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Float glass is crafted by "floating" molten glass on molten tin, a 24/7 process producing up to 800 tons daily. It boasts uniform thickness, glossy, "fire-polished" surfaces, and is nearly colorless with a hint of greenish-blue at the edges. Visible light transmittance ranges from 75% to 92%, based on factors like thickness and clarity. 

Annealed glass, or "ordinary" glass, is the untreated version of float glass, lacking heat-strengthening or tempering. The annealing process involves controlled cooling to prevent residual stress, integral to float glass manufacturing. The hot glass undergoes gentle cooling in the annealing lehr, releasing internal stresses for subsequent cutting and processing. Annealed glass is versatile, allowing cutting, machining, drilling, edging, and polishing. However, it breaks into large, sharp-edged fragments, making it typically unsuitable for classification as "safety" glass.

Heat-strengthened glass, not classified as safety glass, is roughly twice as strong as regular annealed glass of equal thickness. It boasts surface compression ranging from 3,500 to 7,500 psi and edge compression of 5,500 psi or more. Its break pattern mirrors that of annealed glass.

Opaque glass, both translucent and non-transparent, finds use in applications prioritizing privacy, light control, energy efficiency, and aesthetics. Unlike clear glass, it conceals what's behind it while enabling light transmission. Crafted from natural or synthetic materials, opaque glass offers diverse styles, textures, colors, and thicknesses.

Have a look at an opaque glass project Precision Glass installed for a client in the Creston area, just east of Kalispell.

Sandblasted glass is crafted by bombarding the surface with hard particles, yielding a frosted look. However, this process can weaken the glass and lead to permanent staining. Etched glass, offering a maintenance-friendly alternative, has largely replaced sandblasted glass as the industry standard for achieving a frosted aesthetic.

Acid-etched glass undergoes hydrofluoric acid exposure, creating a silky frosted surface distinct from sandblasted glass. This type of glass diffuses light, reduces glare, and excels as a daylighting material. With low maintenance, it resists permanent stains. Unlike sandblasted glass, it's suitable for challenging applications like shower enclosures and building exteriors. Testing is crucial for adhesives, markers, or oil on the etched surface.

Low-E (Low-Emissivity) coating is a thermal performance enhancement applied to the inner glass surface. It reflects long-wave radiation, limiting heat transfer and enhancing the glass U-value. Transparent on float glass and iridescent on channel glass, Low-E coating contributes to improved energy efficiency.

Insulating glass units (IGUs) aim to enhance building efficiency, providing warmth in winter and coolness in summer. These units consist of two or more glass lites spaced and hermetically sealed, forming a single-glazed unit with an air gap. This design minimizes heat transfer and reduces sound transmission. 

Glass is inherently breakable, posing a risk of injury from sharp shards. Safety glass addresses this concern, enhancing occupant safety. Tempered glass, when broken, forms small, less hazardous pieces with a distinctive "dice" pattern. Laminated glass, on the other hand, remains in place when shattered, thanks to its plastic or resin interlayer.

Identifiable by a permanent marking (safety seal), usually found in a corner, safety glass provides assurance. This marking cannot be removed without damaging or breaking the glass, offering a visible indicator of enhanced safety features.

Have a look at some of the custom glass showers Precision Glass has installed using safety glass or tempered glass here on the Precision Glass blog, on our Instagram page, or Facebook page.

Laminated glass consists of two glass plies bonded with interlayers, forming a durable, unified structure. Even when broken, the interlayers support and hold the glass, maintaining strength and safety. Available in different thicknesses and created with various glass combinations or coatings, laminated glass offers versatile qualities, including low emissions or enhanced insulation.

The R-Value represents the thermal resistance of a glazing system, measured per square foot for each 1°F temperature difference between indoor and outdoor air over 1 hour. Essentially, it gauges resistance to heat gain or loss (insulative ability). Comparing R-Values is more meaningful than comparing thicknesses across different materials. For instance, 6 inches of fiberglass (R-19) might equate to 12 inches of wood or 18 inches of stone, highlighting the material's efficiency in reducing heat transfer. The higher the R-Value, the lower the heat transferred through the glass.

Here in the Kalispell, Whitefish, Flathead Valley area we like to see high R-Values even though it increases costs as it'll help with winter energy bills!

The U-Value assesses a window or glass wall's ability to retain heated or cooled air within a building. It quantifies the heat energy transferred across the glass unit, measured per square foot for each 1°F temperature difference between indoor and outdoor air. A lower U-Value signifies superior thermal performance for the glass wall. Enhancements in insulation, lamination, and specialized thermal coatings can effectively improve the U-Value, contributing to better energy efficiency in the building.

It's nice to have lower U-Values even though it increases costs as it'll help with winter energy bills here in the Flathead Valley.

The Solar Heat Gain Coefficient (SHGC) gauges the amount of solar radiation entering through a window or glass wall, indicating the solar heat gain relative to the incident solar radiation.

Conversely, the Shading Coefficient, an older measure, is the inverse of SHGC, denoting the ratio of solar energy passing through the glass in comparison to 1/8" clear glass with a shading coefficient of 1.0.

The ideal solar heat gain varies with climate. In colder climates like here in the Flathead Valley, a higher SHGC is favored for efficient solar heat collection during the winter. In contrast, warmer climates like Southern USA and Mexico benefit from a lower SHGC to block excess sun heat, reducing cooling loads during prolonged air-conditioning seasons.

Relative Heat Gain (RHG) evaluates the heat gain through a glass product, accounting for both the impact of solar heat gain (shading coefficient) and conductive heat gain (U-value). A lower RHG signifies that the glass is more effective in limiting heat gain, making it a favorable choice for managing thermal performance.

Visible Light Transmittance (VLT) quantifies the percentage of visible light (roughly 390 to 780 nanometers in the solar spectrum) passing through the glass. VLT is influenced by both the color and thickness of the glass. Clear float glass typically exhibits VLT ranging from 75% to 92%, while colored glass may have VLT values between 14% and 85%.

AAMA stands for American Architectural Manufacturers Association and establishes standards for the window, door, and skylight industry that are voluntarily followed.