RETRN is a biomaterials company developing tunable PHA based barrier coatings that let paper packaging manufacturers replace plastic liners without changing their production lines. Our aqueous coatings are recyclable with paper, home compostable, and marine biodegradable, and they match or outperform PE lined and PLA lined products on cost and performance. We create high performance barriers using upcycled industrial byproducts and precision fermentation, providing a scalable and affordable alternative to petroleum based plastics. Our formulations integrate directly into existing molded fiber and paperboard systems, giving brands and converters a renewable and non toxic pathway to true circularity. RETRN is based in Ithaca, New York at the Cornell Center for Life Science Ventures and has received competitive funding from STIR and SUNY SF. The company holds letters of support from leading players in packaging and biopolymers, reflecting strong early industry validation.