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Glass Recycling Experiments Help Teach Chemistry


Various grades and colors of glass frit are prepared for firing experimentsVarious grades and colors of glass frit are prepared for firing experimentsInspired by a tour of the Owens Illinois glass bottle and jar factory in Oakland, American High School AP Chemistry teacher Candy Sykes decided to persue her dream of having students recycle glass on campus.

"I want students to go beyond just collecting materials for recycling," notes Sykes, "I want them to actually learn how stuff is made."

With a grant from the Altamont Education Advisory Board, Sykes was able to purchase a glass firing kiln, ceramic molds, and other start up supplies to begin experimenting with glass remanufacturing.

Chemical salts are added to color clear glassChemical salts are added to color clear glass

"We did get some advice from the lead engineer and glass chemists from the factory, but at this point, we are truly experimenting to see what works."

Students are collecting different types and colors of glass, breaking them into course, medium and fine grade frit, arranging a variety of firing schedules, and tracking the results.

"Glass has to cool down slowly or it will de-vitrify," explains Pavritra Ravishankar- one of Sykes's students. "Luckily, we have a programmable kiln, so we can raise the temperature quickly, then specify a cool down schedule to avoid crystalizing the glass."

Experimental results are recorded and mounted to card stockExperimental results are recorded and mounted to card stockTo test different configurations, students are using a mosaic tile ceramic mold to create 1"x1" glass tiles. Sykes hopes to one day create enough tiles for large projects and expand to using shaped molds for creating glass jewlery. Students apply kiln-wash to the mold to prevent glass from fusing to the mold itself, then add glass and any additives.

So far, students have discovered that brown glass melts and fuses the easiest compared to green and clear glass. Medium/course frit produces a nice pebbled texture, and clear glass can be colored by adding various chemical salts to the firing molds.

Pavritra shared the school's results on March 17th at the International Zero Waste Youth Convergence in San Francisco. She and her peers hope to have the process understood and functioning by the end of May so they can share and sell their products at the Maker Faire.