A glass act: Refill and reuse over and over

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Editor's note: This is the second of a two-part series on recycling and reusing glass containers. The first part can be found here.

Glass is not only endlessly recyclable, but was long considered endlessly reusable: For decades, consumers returned used soft drink, beer, water and milk bottles for reuse.

The bottles made their way back to dairies and beverage manufacturers, who sterilized and refilled the containers, a cycle that could go on for as long as a bottle remained undamaged.

But after World War II, refillable glass bottles began falling out of favor. Single-use steel cans became more popular for beer and soda, and paper cartons for milk. Eventually steel was replaced by aluminum and plastic, and by 1998 soft drinks were sold almost exclusively in aluminum and plastic while beer came in aluminum or nonrefillable glass bottles.

Since the early 1970s, "bottle bills" have added a five- to 15-cent tax, or deposit, to the cost of beverages sold in bottles, which is refunded when the consumer returns the bottle. Not surprisingly, glass recycling rates are much higher – 60%, according to the Container Recycling Institute – in the 10 states with bottle bills (California, Connecticut, Hawaii, Iowa, Maine, Massachusetts, Michigan, New York, Oregon and Vermont).

The food and beverage glass that can be recycled curbside is called soda-lime-silica glass, or just soda-lime glass, for the three raw materials used to make it: soda ash, limestone and silica sand, all of which can be sourced in the U.S.

Silica sand melts into glass at high temperatures (3,000-plus degrees F) so it needs soda ash to reduce that melting temperature. Limestone makes melted glass easier to handle and shape, and produces glass products that are hard and durable.

Soda ash (sodium carbonate) comes from trona, a mineral found primarily in Wyoming's Green River Basin. Besides glass packaging, automotive and window glass, soda ash is used in baking soda and dry detergents, fiberglass insulation, water softeners, industrial air purifiers and during the manufacture of items such as sweeteners and paper goods.

Lime (calcium oxide) is extracted from numerous limestone quarries around the United States, and is also used in building materials and construction applications.

Silica sand (silicon dioxide) is essentially pure ground quartz, mined largely in Minnesota, Illinois, Iowa and Wisconsin. Silica sand is also used in paints, ceramics, industrial abrasives, golf course sand traps and during the process of hydraulic fracturing ("fracking") to extract oil and natural gas from shale formations. Although the sand on Great Lakes beaches is also mostly quartz, it contains ground-up rocks, minerals and seashells that make it unsuitable for glassmaking.

Various oxides result in different colored glass: chromium (emerald green), cobalt (blue), cadmium sulfide (yellow), nickel (violet), selenium (red), manganese (purple), iron (browns), and even uranium (yellow-green, which glows under a black light and can be radioactive!).

After being sorted by color, recyclable glass is crushed into pebble-sized pieces called cullet and sold to glass manufacturers, who combine it with these raw glassmaking materials to make new glass.

Soda, lime and silica sand also make up other types of glass such as that used to make drinking glasses, window and picture frame glass, automobile glass, light bulbs, shower doors, baking dishes and even glass art.

Those other glass types often have different ratios of ingredients, may have additional ingredients (such as borosilicate in glass cookware and measuring cups) and undergo special manufacturing processes to produce specific qualities like resistance to high heat, high pressure or extreme temperature changes or the ability to shatter safely and uniformly.

Because the other types of glass have different chemical structures from beverage bottles and food jars, they usually cannot be recycled through municipal programs and should not be put into curbside recycling bins or carts.

A RoundTable reader recently asked about putting broken recyclable glass into the recycling bin. After all, a lot of recyclable glass probably breaks when the bin is dumped into the collection truck and when the load is released into the sorting facility.

The folks at Groot agree: Glass often breaks en route, and broken recyclable glass is acceptable, although it's still best to minimize broken glass in the recycling bin whenever possible.

"Since glass is broken on purpose [before being sold to a glass processor], is the first item removed from the recycling stream and then processed through a mechanical screen, we are not too concerned about us having to handle it during the post-collection process," said Javier Erazo, district manager at Groot.

Nonrecyclable broken glass should be handled differently before setting it out for trash collection. Broken glass, tile and porcelain are "essentially razors" if not properly contained, said Steve Folkerts, district manager of Groot East, and those items can cause serious damage to the people picking up the trash.

Small broken nonrecyclable items – drinking glasses, glass bakeware, light bulbs, picture frame glass – should be put into a cardboard box. Then seal all open edges with packing tape, use a bold marker to label the box "BROKEN GLASS" and put it into the trash bin.

Oversized broken mirrors and windows that won't fit into a box should be sealed with masking, packing or duct tape in a special way and set next to the bin on collection day.

"We ask that residents tape along the entire outer edge of the glass and then tape a spiderweb pattern across the [window] pane," said Folkerts. "This helps to hold the glass together while handling, to prevent us from getting cut by it and dropping glass everywhere." If a large glass item is not taped like this, trash collectors will not pick it up, Folkerts said.

As part of the sustainability mantra "Reduce-Reuse-Recycle," glass jars and bottles can be reused in many ways. Glass containers don't absorb smells or flavors, and reusing them for leftovers and other food and beverage storage reduces the need to buy plastic containers. Both jars and bottles can display fresh flowers too.

At Art Makers Outpost, an art and maker space in south Evanston offering classes for adults and youngsters alike, students repurpose glass jars to make things like snow globes and votive holders.

Founder and Creative Director Val Kahan said jars and bottles collected from the community are popular as a foundation for art projects, and also used to store beads, pompoms, glitter, pine cones, clothes pins, googly eyes, metal springs, sequins, confetti and numerous other items for art creations.

Bea Echevarria, who founded Evanston's Repair Cafe, hosted at the Robert Crown Center, offers additional ideas for reusing glass jars:

"At home we each have a jar in the bathroom cabinet with our own ‘most used’ items [shaving stuff, hair accessories, manicure sets, makeup]," Echevarria said.

She also freezes single servings of meals (chili, soups, rice, etc.), which she defrosts in the fridge and takes to work. There she pops them into the microwave and eats straight from the jar. (Be sure to use freezer-safe glass for this!)

How do you reuse your glass bottles and jars? Please send your suggestions or questions about glass and other types of recycling to [email protected] .

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Meg Evans has written science stories for the Evanston RoundTable since 2015, covering topics ranging from local crayfish, coyotes and cicadas to gravitational waves, medical cannabis, invasive garden... More by Meg Evans