CLEAR (FLINT) GLASS

About 61% of glass containers produced in this country are clear.

Clear glass is made of a combination of silica (sand), soda ash, and limestone.

Marketing professionals often prefer clear glass containers because they make the product inside visible.

However, clear glass may cause some products to degrade because of light exposure. That's why about 39% of the glass produced is colored.

Clear glass is sometimes used for beverages. More often, it's used to package solids or thick liquids, such as pasta sauce, that may not be sensitive to light.

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BROWN (AMBER) GLASS

About 31% of glass containers produced in this country are brown in color.

To produce brown glass, the manufacturer adds nickel, sulfur and carbon to molten glass.

The "brown" in the glass cannot be removed. Thus, brown bottles can be used only to make other brown bottles.

Brown glass protects the container's contents from direct sunlight, thus preserving freshness and flavor.

It is the most common color used for beer bottles.

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GREEN (EMERALD) GLASS

About 7% of glass containers produced in this country are green in color.

To produce green glass, the manufacturer adds iron, chromium or copper to molten glass.

Green glass comes in a variety of shades. The "green" cannot be removed. Thus, green bottles can be used only to make other green bottles.

Green glass helps keep sunlight and temperature from affecting the contents, which explains why it is often used in the manufacture of wine bottles.

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MORE ABOUT RECYCLING GLASS

Some curbside programs and recycling centers take only certain colors of glass. That's because manufacturers who buy the glass have to maintain the integrity of the color when producing new glass.

How Is Glass Recycled?

The glass is taken to a manufacturing or recycling plant where it is broken up into smaller pieces known as "cullet."

The cullet is crushed, sorted, cleaned, and prepared to be mixed with other raw materials.

When glass is produced from virgin materials, it requires high temperatures to melt and combine all the ingredients. Since cullet melts at a lower temperature, the more of it you add to a batch of raw materials, the less energy needed to melt it.

Ceramics such as coffee cups and plates present a problem in the glass-making process because they can weaken the glass. Even a small amount of ceramics can contaminate a whole batch of glass and cost the glassmaker millions of dollars.

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WHAT NOT TO RECYCLE

Not all glass can be recycled. The following items should not be placed into your recycling bin:

1. Any glass contaminated with stones, dirt, and food waste

2. Ceramics, such as dishware, ovenware, and decorative items.

3. Heat-resistant glass, such as Pyrex.

4. Mixed colors of broken glass.

5. Mirror or window glass.

6. Metal or plastic caps and lids.

7. Crystal.

8. Light bulbs: Find out how to recycle here.

9. Cathode-ray tubes (CRTs) found in some televisions and computer monitors.

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