ANNEALED:
Annealed glass is the primary glass product produced from a float glass furnace. Annealing is the process by which the molten glass is cooled. It is not a safety product and has not had any further processing such as laminating or tempering.
TEMPERED:
When broken, tempered glass breaks into a multitude of small fragments of somewhat cubical shape. Tempered glass meeting ANSI Z97.1 requirements is qualified as a safety glazing material.
Tempered glass is fabricated by subjecting annealed glass to a special heat-treating process. Most processes heat the glass to 1150 degrees F., then rapidly cool it by blowing air uniformly onto both surfaces simultaneously. The cooling process locks the surfaces of the glass in a state of high compression and the central core in compensating tension. The color, clarity, chemical composition and light transmission characteristics remain unchanged. Tempered glass is approximately four times stronger than annealed glass. Heat strengthened glass is aproximately twice as strong as annealed glass.
Fabrication, such as cutting, drilling or edging is done before the tempering process.
LAMINATED GLASS:
Laminated glass can be made in many combinations of clear, tinted, low E or solar reflective glasses. Polyvinyl butyral (PVB), the most commonly used sheet interlayer material, is available in thicknesses from .015" to .090", with .030 the most common.
When laminated glass is fractured, the particles of glass tend to adhere to the plastic, affording protection against flying or falling particles. Architectural laminated glass which satisfies the safety requirements for Category II materials, is generally two lites of annealed glass with an .030 interlayer.
Burglar resisting glass covers standards for “smash and grab" type burglaries and tests only for minimal commercial security. It generally uses a special plastic interlayer which is resistant to penetration.
Bullet resisting glass usually consists of multiple lites of glass, plastic interlayers and can include layers of polycarbonate.