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Glass Types and Glazing Information

All windows and doors offered at 1stwindows feature dual paned (also known as dual glazed) glass. If you require a custom glass configuration and do not see it listed please contact us at (562) 494-9069.

Glazing refers to the glass in a window or door and the act or process of fitting a window with glass. There are many different glass types and treatments available. Assembled below are descriptions of the most common glass types.

Low-E Glass
Low-E glass products give you year-round energy savings and comfort by helping manage the sun's energy and the heating system energy in your home. Low-E glass products are coated with microscopically-thin, optically transparent layers of silver sandwiched between layers of antireflective metal oxide coatings. In the summer, Low-E glass products let in visible sunlight while blocking infrared and ultraviolet solar energy that drives up cooling costs and damages curtains, window treatments, carpeting and furnishings.  And in the winter, Low-E glass products offer greater comfort and reduced heating costs by reflecting room-side heat back into the room. Emissivity is a measure of how much heat is emitted from an object by radiation. Heat is transferred to and from objects through three processes: conduction, convection, and radiation. For instance, on a hot night, heat will be conducted through a window from the outside, causing the inside pane to become warm.

Convection, or natural circulation, of the air in the room past the window will transfer some of that heat into the room. But the window will also radiateheat as infrared waves, which will warm objects throughout the room. This radiative heating is why you can feel the heat of a red-hot piece of metal (for instance, a heating element on an electric stove) from several feet away. Low-emissivity, or low-e, coatings are put on window panes to reduce the amount of heat they give off through radiation. In hot climates, where the outside of the window will typically be hotter than the inside, low-e coatings work best on the interior of the outside window pane. In cold climates, where the inside of the window is typically hotter than the outside, the low-e coatings work best on the inside window pane, on the side that faces toward the outside.

Laminated Glass
Laminated glass is produced by permanently bonding two pieces of glass together with a tough plastic interlayer (polyvinyl butyral) under heat and pressure. Once bonded together, the sandwich behaves as a single piece.  The interlayer is invisible when viewed through the glass and with glass on either side, the finished lite is indistinguishable from plain glass when installed. Most often, laminated glass is produced from annealed glass, but heat strengthened or tempered can be used when special performance needs are present. The benefit of laminated glass is that if broken, glass fragments adhere to the plastic interlayer rather than falling free and potentially causing injury. Laminated annealed glass can be cut or drilled. Laminated glass is required in sloped glazing applications that exceed any of the following conditions: 
The area of each pane (single glass) or unit (insulating glass) exceeds 16 square feet. 
The highest point of the glass is greater than 12 feet above any walking surface or other accessible area. The nominal thickness of each pane exceeds 3/16 inch.

Laminated glass is highly effective in reducing noise thus improving Sound Transmission Ratings. The best design incorporates laminated glass in an insulated unit. The damping characteristics of the plastic interlayer combines with the attenuating characteristics of the air space of the IG unit to maximize sound reduction. Example: Two lites of 1/4" laminated glass in an IG unit with a 1/2" air space provide an STC rating of 42. This compares with two pieces of monolithic 1/4" glass in an IG unit with a 1/2" airspace the STC rating would be 35. Laminated glass eliminates 99.9% of ultraviolet rays, making it highly effective in protecting furnishings, displays, merchandise, etc. Standard laminated glass is 7/32" with a .030 (approx. 1/32") polyvinyl butyral layer.

Tempered Glass
The tempering process produces highly desirable conditions of induced stress which result in additional strength, resistance to thermal stress and impact resistance. Fully tempered glass must have a surface compression of 10,000 PSI (Annealed is below 3500 PSI) and heat strengthened must have a surface compression between 3,500 and 7,500 PSI. The basic principle employed in the heat treating process is to create an initial condition of surface and edge compression. The condition is achieved by first heating the glass, then cooling the surfaces rapidly. This leaves the center glass thickness relatively hot compared to the surfaces. As the center thickness then cools, it forces the surfaces and edges into compression.

Wind pressure, foreign object impact and thermal stresses or other applied loads must first overcome this compression before there is a possibility of breakage. In the heat treatment process the key procedure is application of a rapid air quench immediately upon withdrawal of hot (1200 degrees F) glass from the tempering furnace. The immediate and sustained application of an air quench produces the temper. A quenched condition becomes stable when the glass is reduced to a temperature of approximately 400-600 degrees F. Tempered glass is about 4 times stronger than annealed.

Solar Bronze
A brown 'smoked' tint. Designed to reduce solar heat gain.

Solar Gray
A gray 'smoked' glass designed to reduce solar heat gain.

Unique among all tinted glass, offering a dark-gray, almost black appearance which provides excellent glare control, shading coefficient and ultraviolet screening.

A green float glass that has excellent light transmittance and reduces solar heat gain.

A green tinted, spectrally select glass that provides a high daylight transmittance and UV transmittance.

This spectrally select glass has an 'aquamarine' appearance and is excellent for high daylight transmittance and has a low shading coefficient.

Reflective Glass
The reflective coating is applied just like hardcoat Low-E through spraying (Pyrolitic process) during the float glass manufacturing process. It reflects light and heat with a metal oxide coating giving a mirror effect and minimizes solar heat gain, and ultraviolet light damage to interior as well as providing daytime privacy. May be tempered.


Heat absorbing and heat reflective glass can only be used on the exterior lite of a unit in order to avoid a build-up of heat inside the airspace, which will cause thermal stress cracks or seal failure. Reflective type glass works with the play of light. Example: During daylight hours you can't see inside a building with reflective glass, (only your refection). At night there is just the opposite effect. You can see in, but the people inside can not see out.

Types of Reflective Tints

Solar Cool Gray
Solar Cool Bronze

Light and heat reflective. Has a low daylight transmittance, shading coefficient and relative heat gain.

Bronze Eclipse
Gray Eclipse
Blue-Green Eclipse

These are light and heat reflective. They have a low daylight transmittance, shading coefficient and relative heat gain.

Heat Mirror
Heat Mirror film is a window insulation material that is transparent to light, but highly reflective to heat. It consists of a specially coated film which is mounted inside an insulating glass unit, midway between the panes of glass. The result is a finished product which looks clear, but has a dramatically improved insulation performance. Compared with ordinary types of glass, Heat Mirror dramatically reduces heat loss and heat gain caused by conduction and radiation. These are two of the primary methods by which heat transfer occurs in glass. The third is convection.

Ordinary double pane and triple pane glass only reduce conductive heat flow, and have little effect on the radiated component of heat flow.

Heat Mirror combines a low-E coating with two air spaces to block both radiated and conductive heat flow. This unique construction enables Heat Mirror insulating units to offer higher insulating performance than other high performance glazing options. The transparent Heat Mirror coating is actually 90% as reflective as aluminum foil. It is optically clear and reflects heat back to its source.

Because there are many climatic regions in our sales area, there is a family of Heat Mirror products to provide optimum thermal performance for virtually any application in a wide range of climates. Similarly, within a climatic region, each specific application has different performance requirements on each elevation. The higher the Heat Mirror number (i.e., Heat Mirror 88 and SC75) the higher the solar transmission. Heat Mirror products with the highest numbers provide higher levels of visible light transmission and solar heat gain. The lower numbered products (HM 66, 55, 44) provide the best control of solar heat gain for the optimum control performance in southern climates on homes with significant solar exposure, or glass-intensive structures such as sky-walls.

Heat Mirror 88 is designed for northern climates, where warmth from the sun is desirable for supplemental heating. Heat Mirror 77 and 66 are designed for climates where overheating is the primary concern or on elevations like the south and west sides of a house where overheating can occur, even in the north. Heat Mirror 55 and 44 provide even greater levels of solar control for skylight, sunrooms and commercial buildings.

Heat Mirror Benefits
Superior insulation performance - has twice the insulation performance of standard insulating units.
Ultraviolet fading protection - Blocks out 99.5% of ultraviolet rays.
Provides improved sound control - Reduces outside noise 12% more effectively than standard insulating units.
Design freedom - Can increase the glazing area in the design of a home or commercial building because of its high performance characteristics.
Excellent shading coefficient
Excellent U-values

Obscure Glass

Some obscure or pattern glass gets its pattern by going through rollers after the float glass process that have the pattern on the rollers. It adds privacy where window covering are impractical or undesirable (bathrooms, sidelights) and is available in various colors and texture patterns provide a translucent of semi-opaque effect. It may or not not be tempered.

Types of Obscure Glass

Our standard Obscure pattern

A fine etched pattern glass that is made by pouring an epoxy on the glass and letting it dry in a high humidity environment. The glue is then chipped away which removes portions of the glass.

A type of obscure with a vertical reed pattern.

A type of obscure with a rain pattern.

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