The glasses used in general are made of lead-free glass. Compared with lead-free glass, lead glass is known as artificial crystal and has good transmittance, but the manufacturing cost is much higher than lead-free glass, so it is expensive. Such as photographic lenses, Swarovski jewelry and British glass crafts are all made of lead glass. Not to mention spreading the goods, even drinking glasses can not be made with expensive optical glass unless you are a super local with the ability to make glass.
There are many uses and types of lead glass, such as the manufacture of optical glass, electric vacuum glass, low temperature sealing glass, radiation protection glass, lead crystal glass, flint optical glass, low melting glass, delay line glass, high refractive microsphere Glass and high-end artware glass, etc.
The English name of lead glass is "lead glass", and if there is a "full lead" logo, its cost is more than natural crystal with the same volume or weight.
The composition formula of lead glass is: RmOn-PbO-SiO2 (B2O3). In the formula, SiO2 (B2O3), that is, silicon oxide (boron oxide), is called the network formation, and is the basic unit that constitutes the glass network structure. RmOn, a metal oxide representing alkali, alkaline earth, and rare earth metals, is a network modification that changes the structure of the glass network of e79fa5e98193e58685e5aeb931333363396333 to achieve adjustment characteristics. PbO, or lead oxide, is a characteristic component that imparts basic characteristics to glass. With the increase of PbO content, the performance index values of glass such as density, refractive index, dispersion, dielectric constant, absorption coefficient for X-ray and γ-ray increase; its index values of hardness, high-temperature viscosity, softening temperature, chemical stability and so on decrease; As a result, the glass molding material becomes longer, the coloring agent is bright, the surface gloss is increased, and the knocking sound is crisp.
In the second half of the 17th century, Britain produced lead crystal glass artware. Later, it was widely used to manufacture optical instruments and art utensils. Early German Leica lenses and Swedish Hasselblad lenses all used full lead glass, so the imaging quality was extremely excellent, and the price was significantly higher than that of Japanese lenses.