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January 21, 2025 | Katelyn Biefeldt

Meet the Knoxville entrepreneur ‘shattering the limitations’ of recycled glass

Dr. Alex Stiles is the founder of two companies: Vitriform 3D and Fourth & Glass, both targeted toward recycling discarded glass.

Dr. Alex Stiles is on a mission to turn waste into something durable, valuable, and eco-friendly. His company, Vitriform3D, is breathing new life into discarded glass— showing the world that used glass is not trash.

teknovation.biz readers may already know about Vitriform3D from its participation in Cohort Six of the Innovation Crossroads program at Oak Ridge National Laboratory (ORNL). Through the support of the U.S. Department of Energy (DOE), Stiles has been working to commercialize 3D printing using recycled glass for a wide range of applications. But since completing the program, his focus has narrowed—he’s now using glass waste to 3D print exterior cladding, a durable material used on the outside of buildings.

Glass bottles take a million years to degrade in a landfill, and our landfills are full of them,” Stiles said, “Yet, glass materials are infinitely recyclable and have so many practical applications and purposes.”

Despite this potential, approximately eight million tons of glass in the U.S. end up in landfills each year. Stiles pointed to a glass recycling program in Blount County, which uses a glass crusher to create materials for filling holes in asphalt roads, as an example of how glass waste can be repurposed.

Crushed glass sample.

Yet, when Stiles looked at Knox County, he saw shortfalls in the local glass recycling program.  According to the county’s recycling website, glass waste cannot be included in the residential curbside recycling bins; however, it can be physically driven and dropped off at one of the five city recycling centers.

“Unfortunately, most people won’t do this, unless it’s convenient to them, or they feel passionately about the cause,” Stiles said.

Recognizing a gap, Stiles saw an opportunity to create mutual benefit for both the community and Vitriform3D. Community members wanted to recycle their glass, and he needed a supply of it for his research and development efforts. That’s when Fourth & Glass was born—a glass recycling service that took on a life of its own.

Fourth & Glass recycling bins.

Each month, Mandy Tietjen, Fourth & Glass’ Operations Manager drives over 300 miles, collecting glass from 160 subscribers across the Knoxville area. This steady supply of recycled glass has allowed Stiles to experiment with various types of glass, studying their aesthetics, melting points, durability, and practical uses. His R&D efforts have ranged from solar panel glass and wind turbine blades to colored wine bottles and kombucha jugs, all in pursuit of the ideal materials for 3D printing.

Thanks to the Fourth & Glass venture, Stiles found himself with a seemingly endless supply of glass. He soon asked himself, “What should we do with all this unused glass?”

The answer: create something new. A few months ago, Fourth & Glass launched an Etsy shop selling sea glass, durable glass coasters, and home décor—all made from crushed, recycled glass.

“The Fourth & Glass side of the business allows us to explore more artistic applications for recycled glass and test different manufacturing methods at a small scale. What we learn here will help us eventually scale up Vitriform3D,” he said.

Stiles preparing glass mixture for repurposing.

Stiles has successfully created multiple revenue streams, solving one problem while simultaneously fueling his larger goal of bringing 3D-printed glass products to market.

On December 3, Stiles began work on a DOE-funded project to leverage 3D printing with glass materials to produce low-embodied carbon, fire-resistant exterior cladding. This composite material must consist primarily of glass to achieve the desired properties.

“The 3D printing for this project requires very advanced manufacturing technology. So, we’re testing different materials in the printers starting with small prints and scaling up,” he said.

Stiles expressed excitement for the continued R&D backed by the DOE. He credited his mentor, Dr. Uday Vaidya at the University of Tennessee, Knoxville (UTK), the Spark Innovation Center at UT Research Park at Cherokee Farm, and Innovation Crossroads for their key roles in Vitriform3D’s success.

He also acknowledged the support of the Knoxville community in embracing his ideas and welcoming a new recycling program to the area.

While his companies are still in the growth stage, Stiles said he is inspired by the momentum he’s seeing in the local entrepreneurial community.

“Look at Anca Timofte with Holocene, Anna Douglas opening a huge lab space for Sky Nano, Sarah Jordan buying a foundry in Ohio, Nth Cycle receiving national recognition, and Kim Tutin launching a large pilot program. So many Innovation Crossroads graduates are doing great things,” he said. “We’re excited to keep building Vitriform3D and to have the support of the DOE behind us.”

Learn more about the Fourth & Glass recycling program.

Read more about Vitriform3D.

Connect with Alex Stiles.



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