leadglass

Lead glass is a type of glass that contains a substantial amount of lead oxide, typically 18 to 40 percent by weight, which increases its density and refractive index. The resulting material is highly transparent and often displays a brilliant edge when cut and polished. Lead glass is commonly referred to as lead crystal in the context of decorative tableware and optical components, though the two terms are used variably in commercial settings.

Composition and variants: The PbO content and the presence of other oxides such as boron, zinc, or barium are adjusted to balance workability, durability, and optical performance. Flint glass is a historical name for high-PbO formulations. Compared with soda-lime glass, lead glass has higher density and a higher refractive index, giving rise to improved dispersion and a characteristic crystal-like brilliance. It is relatively soft and can be scratched more easily than ordinary window glass, and it may be more susceptible to thermal shock.

Applications: In tableware and decorative objects, lead glass is standard for crystal glassware due to its brilliance and weight. In optics, historical prisms and lenses used lead-containing glasses for favorable refractive properties. Leaded glass is also used in radiation shielding windows in medical, industrial, and research facilities; the lead oxide content attenuates X-ray and gamma radiation, with the required thickness determined by the energy of the radiation.

Safety and regulation: Because lead can leach into foods or liquids, lead glass is subject to regulation in many jurisdictions and is discouraged for cookware. Modern safety standards often specify maximum lead content or restrict use to non-food applications. In shielding contexts, leaded glass is designed to minimize exposure while maintaining visibility; sometimes alternative heavy metal oxide formulations are used.