Annealed Glass - Annealed glass (sometimes called “float glass”) is what most of us think of as “normal” or “standard” glass; created through the heating process described above, annealed glass is then cooled at a specific rate and temperature. Annealed glass will break into large uneven shards when broken, and does not have the increased strength that tempered glass does. Annealed glass is typically the most economical option, and is most commonly used where potential breakage does not create a safety hazard.

Heat-Strengthened Glass - Featuring a surface compression of 3500 psi to 7500 psi, heat-strengthened glass is approximately twice as strong as annealed glass. When broken, heat-strengthened glass will break into a pattern similar to annealed glass, forming large and potentially dangerous shards. Heat-strengthened glass represents an intermediate between annealed and tempered glass, useful in situations requiring increased strength, yet not used in potentially dangerous applications. Tempered glass has become very affordable due to technological advances, and for that reason heat-strengthened glass is no longer commonly used.

Tempered Glass - Safety-tempered glass is created in a similar process to annealed and heat-strengthened glass, yet tempered glass is both heated to a higher temperature and cooled more rapidly. This process creates the glass that we are used to seeing in our car windows, where breakage fragments the glass into “a million tiny pieces.” Tempered glass is commonly used for commercial applications where unsafe situations may be created if the glass were to break (for example above doorways or near stairs). In fact, United States Uniform Building Code requires that tempered glass be used in some cases, such as in doors, or directly adjacent to them. While tempered glass is about 4-5 times more resistant to breakage than standard annealed glass, it is slightly more fragile at the edges. Tempered glass is also typically slightly more expensive, owing to the increased labor and energy used to heat it to a higher temperature. PLEASE NOTE: Because tempered glass will completely shatter, or “explode,” when broken, it cannot be cut down after it is cooled, meaning that measurements provided to the glass factory will have to be exact, or the glass piece will have to be remade entirely. TEMPERED GLASS CAN NEVER BE CUT.

Careful consideration must be used to determine the right glass for your project. When selecting glass, one might ask oneself:

• What will I use this glass for?
• If this glass breaks, would large and sharp shards create the chance to injure someone, or their pet?
• Will I need to cut or sand this glass in the future?
• Does Building Code (UBC) require a certain type of glass? 

No matter the size or complexity of your project, A-1 Glass & Mirror stands ready to assist. And if you’re not quite sure about the type of glass you will need, the friendly glaziers and staff at  A-1 Glass are happy to offer our advice and experiences. Call us today at 503-646-9641 for assistance with your glass needs.