Crystal (from other Greek: κρύσταλλος - ice [1] ) is a special type of glass containing at least 24% lead oxide (PbO) (or barium oxide (BaO)) [2] . The addition of lead oxide increases the refractive index of glass and the dispersion of light in it (from the jewelry point of view - “play of color”, “fire”). The addition of barium oxide generally only increases the refractive index. The addition of lead oxide also increases the plastic properties of glass and, accordingly, the possibilities for processing it - cutting, carving, etc. Cutting crystal, like cutting precious stones , allows crystal to fully exhibit properties due to its high refractive index and dispersion. The name was given by analogy with rock crystal .
They are made by fusing lead oxide PbO with silica , a compound of sodium or potassium ( soda or potash ) and small additives of other oxides . Lead-potassium-silicate glasses are more expensive than calcareous glasses, but they are easier to melt and easier to manufacture. This allows the use of high concentrations of PbO and low - alkali metal - without compromising fusibility. The high content of PbO gives high values of the refractive index and dispersion, two parameters that are very important in some optical applications. The same characteristics add sparkle and luster to lead glass, adorning the most sophisticated tableware and works of art.
Content
Crystal Glass
Crystal glass is a lead-silicate glass containing 13-23% of lead oxides and up to 17% of potassium oxides. Crystal glass produces high-quality tableware and decorative products. It has increased density, transparency, refractoriness and gloss, but less heat resistance compared to other types of glasses. Due to the content of lead and a certain selection of angles formed by the faces, crystal products are distinguished by an unusually bright, multi-color play of light. Possess a beautiful ringing. Crystal is also called high-quality Venetian and Czech glass. The style of art glass (crystal) is solemn, ceremonial, souvenir-gift. Methods of processing crystal products: engraving , cutting , carving , grinding .
The addition of lead oxide to the glass mass was practiced even at the dawn of glass making, in ancient Egypt and Mesopotamia . Nevertheless, crystal in a more or less modern form was obtained only in 1676 by the English craftsman George Ravenscroft.
Crystal Producers
International code indicating that lead glass can be recycled
Operating plants in Russia
- Dyatkovo Crystal Plant , Dyatkovo
- Gusevskoy Crystal Plant , Gus-Khrustalny
- Bakhmetyevsky Crystal Plant, Nikolsk
Operating factories in Belarus
- Glassworks "Neman" , Beryozovka
Closed factories
- Leningrad art glass factory ; production closed January 29, 1997 .
- Factory "Red Giant" , Nikolsk ; production has been closed since the end of 2008 .
- Crystal site of the Taganrog Metallurgical Plant , Taganrog ; production closed at the end of 2012 .
- Borisov Crystal Plant named after F. E. Dzerzhinsky , Borisov closed
- Pervomaysky glass factory , Smolensk region is closed
See also
- Goose Crystal
- Dyatkovo and Dyatkovo Crystal
- Rhinestone
- Swarovski
- Uranium glass
Notes
- ↑ see at Fasmer
- ↑ Crystal - an article from the Great Soviet Encyclopedia .