Photography by Brian Klutch

Any time a drop of water rolls off a raincoat, a durable water repellent (DWR) treatment is doing its job. But with washing and wear, the treatments tend to rub off, bleeding into the ground, water, and even our bodies. (The EPA has classified common DWR chemicals, perfluorinated compounds, as toxic.) Schoeller’s Ecorepel is the first DWR to perform as well as—or better than—other treatments (without toxins).

Ecorepel, up close

Long honeycomb-shaped paraffin molecules form a lattice over each fiber. The lattice is too fine for water molecules to penetrate, so water beads and rolls off, but it’s still permeable enough to allow airflow.

Ecorepel uses paraffin wax, the same material that sailors once employed to water-treat their outerwear, but with a cleaner and longer-lasting application. Technicians dip garments into a milky paraffin solution, run them through rollers to wring out the excess, then bake at 300°F. As the paraffin cures, it wraps around individual fibers. Ecorepel, unlike other treatments, won’t wear off from washing or abrasion, which makes it ideal for clothes that take a lot of abuse, such as jeans. For example, Levi’s will debut Ecorepel on its 511 Commuter Jeans and a denim jacket this summer. In their tests, the coating held up through aggressive rubbing and at least 20 washes.

This article originally appeared in the May 2014 issue of Popular Science.