Final answer:
Glazing materials are assessed for resistance to mechanical and thermal stress, as well as changes in optical properties under stress.
Step-by-step explanation:
Glazing materials are evaluated for their resistance to mechanical stress, thermal stress, and optical properties when stressed. Glass, a major material used in glazing, is a non-crystalline amorphous solid primarily made from silica (silicon dioxide), which is transparent even when colored. Standard glazing glass, known as soda-lime glass, consists largely of silicon dioxide, sodium oxide, and calcium oxide with minor additives, and is commonly used in windows and tableware.
Soda-lime silica glass is preferred for its transparency and ease of formation. However, it's crucial to consider its high thermal expansion and poor heat resistance when evaluating glazing for protective measures. When optical stress analysis is required, plastic models can be observed through crossed filters, as they become optically active under stress, revealing the effects depending on the wavelength.
Furthermore, protective measures such as eyewear should consider UV protection. Materials like polycarbonate in plastic lenses offer superior UV filtering compared to ordinary glass. Even untreated glasses provide some UV protection, though full coverage is optimal to shield against light from various angles.