The Color Significance of Glass
Glass comes in many different colors, which is affected by what coloring ions and elements are added to the glass during production.
While this process can create very colorful material such as stained glass, for recycling purposes you will usually only come across four different colors of glass containers. Here is a quick breakdown of the colors:
Colorless Glass
Colorless glass is exactly what it sounds like: glass that is completely transparent because it is devoid of color. It is sometimes referred to as “clear” glass, but “colorless” is a more fitting description because this type of glass is carefully made to avoid the presence of color.
You will most often find colorless glass in everyday places, such as the grocery store. Pasta sauce or peanut butter jars and some beer and spirits bottles use colorless glass as well.
Green Glass
Green glass has more variety of shades than any other color, making it a popular color choice for glass bottles. Green glass is usually “colored” using metals like iron, chromium or copper.
Green glass is better at keeping sunlight and temperature from affecting the contents inside, which explains why this form of glass is most often used for wine bottles.
Blue Glass
Blue glass is formed naturally as the result of iron impurities found in most sand. To create a darker blue in the bottle, cobalt oxide can be added during manufacturing.
Blue glass was much more popular in the U.S. prior to the 1920s and is now used mainly for clear liquids such as liquors or ink bottles.
Brown Glass
Also known as “amber” glass, brown glass is produced with the addition of nickel, sulfur and carbon during manufacturing. Because of its similar hue to green glass, a small amount of brown glass can be used to produce green glass bottles and vice versa.
Brown glass is the most common color for beer bottles, because of the necessity for light protection for the beer inside.
Significance of Color
You will find that some curbside programs and recycling centers only take certain colors of glass, mostly because the manufacturing plants need to maintain color schemes when producing new glass containers.
You can search for recycling locations for clear, green, blue and brown glass using Earth911.
