When it comes to recycling, knowing what not to put in the bin is sometimes just as important as getting the right materials in there in the first place.
This author had her own epiphany about recycling rules while researching this particular article: not all glass is created equal.
"It's just like dealing with different polymers in the plastic industry," said Joe Cattaneo, president of the Glass Packaging Institute (GPI), the trade association representing the North American glass container industry. "Just because it looks the same doesn't mean it is all the same."
Additives = Contaminants
Most recycling programs are set up to process container glass, like beverage bottles or condiment jars. This class meets certain regulations to be certified safe for food.
But the glass that makes up everyday houshold items like ovenware, drinking glasses, incandescent light bulbs, windows, windshields and mirrors contain materials like lead and plastic that cannot be mixed with container glass.
Let's take the example of windshields, for example. According to a representative working in the windshield recycling industry, windshields have a layer of plastic "sandwiched between the glass." This plastic is a contaminant in the recycling stream and is very difficult to remove. "There is a machine called a windshield stripper," he tells Earth911. "It's an expensive piece of equipment, upwards of $100,000. It basically liberates the plastic from the glass."
Windshields, like other types of non-container glass, have specific, and sometimes limited, recycling options. For example, this representative's company recycles glass from obsolete or broken inventory from manufacturers and does not accept materials directly from consumers.
"Consumer with a windshield more or less has to throw it away because to bring it to us costs more money than that glass is going to be worth," he says.
Additionally, because glass is recycling using a heat-intensive melting process, the different chemical compositions and tempering found in non-container glass can vary.
"The issue with glass containers, or soda lime glass, is that it can get contaminated by other types of glass such as ovenware, because [ovenware is] a much stronger tempered glass that's made to be reused and in the oven and microwave," says Cattaneo. "It's a higher durable glass that won't melt at the same temperature as typical bottles and jars. It will cause stones that will make the 'regular' soda lime glass break."
This goes for your coffee mug, too, because ceramics have different chemical compositions than container glass.
Stronger forms of glass made to withstand high levels of heat of environmental stressors can also damage equipment in recycling facilities.
"In fact, glassware, ceramics, window panes, or mirrors can pose a threat to equipment in a glass recycling plant," according to the Washington State Department of Ecology.
What You Can Do
So what does this mean for the rest of us, exactly?
Just like other recycling streams, it's better to not add materials to the bin that may cause problems down the line than assuage your "green guilt" at tossing more in the trash.
Cattaneo's advice is also not leave it up to chance whether or not your glass will actually get recycled.
"There certainly are some types of drinking glasses, for example, that could be mixed with soda lime glass, but "it's so difficult to discern one from the other. The issue is is that often they could be decorated or they could have lead in them. Lead crystal isn't meant to be recycled, it's meant to be reused over and over and then thrown away."
Don't let the word "lead" make you nervous though. According to Cattaneo, "Glass does not contaminate landfills; it's inert."
Cattaneo also cautions against being too general. "[Potential glass recyclers are] probably going to have to look in their own community on where they can get that taken care of."
Glass Projects Abound
While it may be a bit tough to find ways to reuse a broken windshield (We're open to suggestions!), drinking glasses and ovenware pieces can be reused in a number of facets.
A word of caution: Do be careful when crafting with glass. This advice via Associated Content might be smart to start off: "If you want to use them for something that requires you to smooth the edges and make them safe, you can do so by squeezing hot glue along the edges or by covering the edges with masking tape. You can also use a Dremel or other small sanding tool to smooth down the edges. Be sure to wear safety goggles and heavy duty gloves to protect your hands."
Check some of these cool projects the next time you get hit by a clumsy moment:
- Light up your home with a broken glass suncatcher via Craftbits.com
- Make your own glass beads via Instructables
- Get inspired to make your own jewelry with pieces from Bottled Up Designs
- Grab a drink from glasses made from broken wine bottles via Instructables
- Store up your broken pieces for an illustrated mosaic via Mosaicartsupply.com
Earth911 partners with many industries, manufacturers and organizations to support its Recycling Directory, the largest in the nation, which is provided to consumers at no cost. The Glass Packaging Institute is one of these partners.