How Is Lead Crystal Manufactured?
Most people have heard of Waterford crystal, pieces of glass made into intriguing and unique shapes for a variety of uses. Waterford crystal, manufactured in Ireland, along with that manufactured by others such as Swarovski in Austria, Steuben in the United States, and Mikasa in Japan, are much-sought products.
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History
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Glass products dating as far back as the third millennium B.C. have been found in Mesopotamia. The skill was brought to Europe, where it eventually flourished beginning at the end of the 13th century. Venice, Italy, became a famous center for glass making. It took another two centuries before lead crystal was discovered by George Ravenscroft, an Englishman, in 1676. By adding lead oxide to the mix of silica (sand) and potassium, Ravenscroft created glass products that were more brilliant, cleaner, and stronger than standard glass.
Composition
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Lead crystal differs from regular crystal in its lead content. Standard crystal contains no lead at all, whereas crystal classified as "lead crystal" must contain at least 10 percent lead oxide. The higher the content of lead oxide, the harder it is to work with. The artisans must be more highly skilled, making the end products more valuable.
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Manufacturing
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A mixture of sodium, potassium, silicone and lead oxide are heated to a temperature of 3,600 degrees Fahrenheit, then very slowly cooled to a manageable working temperature. The molten glass can then be blown or otherwise shaped into an endless number of designs. Further cooling "sets" the shape permanently. Interestingly, if the purest white sand is not used, the glass will have a greenish tint because of the iron content in lower quality sand.
Advantages
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The lead in lead crystal makes it softer than regular glass, making it easier to cut but harder to blow and form. The lead also increases the refractive index, giving lead crystal more sparkle and making it less brittle. This makes more complicated and deeper designs easier to cut into the glass.
Considerations
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Besides decorative and useful pieces such as goblets, dishes, and jewelry, some adherents of alternative healing believe lead crystal can turn negative energy into positive energy, creating a balance of bio-energy. But the most common lead crystal products are goblets and decanters. Caution needs to be taken when drinking from lead crystal products. Over time, the lead can leach into the liquid in the container. Great Food Finds, a magazine about specialty foods, recommends not storing alcoholic products in items such as lead crystal decanters.
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References
Resources
- Photo Credit crystal glass image by peter Hires Images from Fotolia.com
