Lead Oxide Makes it Crystal - How Does That Work?

Glass is formed when sand, caustic soda or potash and lime are exposed to high temperatures. Glass is produced in nature under the right conditions. Ancient man used bits of natural glass in artwork and for decoration. Archeologists found Egyptian glass beads that date back to 2500 BC. It took more than a thousand years to learn how to make glass.

Glass molding, where chips of glass are melted and formed into shapes, did not occur until about 150 BC. Glass-making developed over the centuries as glass-blowers experimented with techniques and additives. In the 15th century, glass-blowers used lead oxide to create a colorless glass that looked like rock crystal. The glass-making industry continues to improve glass quality and expand its uses. Today, glass in all shapes and sizes is used in the home, in industry and to celebrate special events and contributions with crystal awards and trophies.

All glass begins as a mixture of silica from fine sand, a caustic ingredient such as sodium bicarbonate or potash and lime. Additives such as lead oxide (lead crystal), iron chromate (green color) or cobalt (blue color) can be added before melting. This mixture is melted in a furnace at 2,500 degrees Fahrenheit for as long as 24 hours. The melted glass, which is a thick hot liquid, is then cooled to a working temperature. Once it can be worked, the glass is blown, rolled or pressed into its desired shape. Finally the glass pieces are placed into a cooling oven to complete the process.

The addition of lead oxide lowers the temperature and thickness of the melted glass. This makes the melted glass easier to work. Lead oxide also produces a more brilliant glass product. Glass-blowers can produce beautiful decorative pieces more easily. Lead crystal is used for crystal awards, sculptures, chandeliers and other elegant home décor.

You can tell the difference between lead crystal and cut glass. Lead crystal is generally heavier than glass of the same size and shape. Lead crystal is transparent and will remain clear in the light, whereas glass may be tinged green or yellow. Lead crystal will produce a pinging sound when lightly tapped; standard cut glass does not have this property.

The addition of lead oxide makes the melted glass softer and easier to mold into crystal awards and decorative pieces. Lead oxide also makes the finished product softer. Accumulated dust can be abrasive and scratch the surface of the crystal. It is important to clean your crystal with a mild detergent and lint free cloth. Leaded crystal awards and keepsakes can be enjoyed for many years with a proper maintenance.

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