How Fluorescent Bulbs Are Made
Compact fluorescent bulbs (CFLs) are made using the same basic technology as the traditional fluorescent bulb, which has been in use for nearly a century. They are made from two main parts, which include a simple glass tube and a electric ballast. The inside of the tube is coated with phosphorus. Electricity passes through the ballast and produces ultraviolet (UV) light. This UV light interacts with the phosphorus coating on the bulb, causing it to glow bright white, producing light that is emitted from the bulb. Though this technology has been around for many years, the ballasts were always too large to fit into most residential fixtures. It wasn't until the 1980s that scientists were able to shrink the ballast and create the compact fluorescent bulb.
The Spiral Shape
Many people associate CFLs with their unique spiral shape. This spiral pattern is made using machines specifically designed to spin glass. Once the bulb is cool, the air is vacuumed out, and small amounts of mercury gas are added. The spiral shape of these bulbs was built out of necessity. Because fluorescent bulbs produce light only from their phosphorus coating, there needs to be a certain amount of surface area available for this coating. The spiraling glass tube provides the maximum amount of surface space in the smallest total area, which allows the bulb to produce sufficient lighting for most applications. Early attempts at using a standard round bulb produced dim and off-color lighting that did not appeal to consumers.
Types of CFL Bulbs
Several new advances have led to new shapes and sizes of CFL bulbs. As ballast technology has improved, manufacturers have begun to shrink the traditional spiral bulb, allowing it to better fit into most light fixtures. In 2008, the A-shaped CFL bulb was introduced. This bulb is made by fitting a spiral CFL inside a regular light bulb shape, giving it a kind of "ship in a bottle" look. Globe CFLs feature spiral bulbs tucked inside round bulbs, and are designed for bathroom vanities and ceiling fan lights. Finally, some CFL bulbs feature layers of tubing that are placed inside candle-shaped bulbs. The bulb is frosted to hide the tubes, making them a popular choice fr decorative light fixtures.