What makes a fabric biodegradable?

A fabric is biodegradable when microorganisms — bacteria, fungi, and other decomposers — can break it down into natural elements like water, carbon dioxide, and biomass within a reasonable timeframe. This capacity depends primarily on the chemical composition of the fiber. Natural fibers like cotton, linen, hemp, wool, silk, and alpaca are inherently biodegradable because they are made of cellulose or protein structures that microorganisms recognize and can digest. Regenerated cellulose fibers like Tencel lyocell are also biodegradable for the same reason.

Synthetic fibers like polyester, nylon, and acrylic are not biodegradable because they are essentially plastics — long-chain polymers derived from petroleum that microorganisms cannot effectively break down. A polyester garment can persist in a landfill for 200 years or more, fragmenting into ever-smaller microplastic particles but never truly decomposing.

However, biodegradability in finished garments is more complex than fiber content alone. Dyes, chemical finishes, synthetic threads, plastic buttons, and elastane blends can all impede or complicate biodegradation. A cotton shirt sewn with polyester thread and finished with a synthetic coating will not biodegrade cleanly. This is why brands like Reprise Activewear go beyond just the fabric — every component, including thread, labels, and dyes, is plastic-free to ensure genuine end-of-life biodegradability.