How can I check if a fabric is truly natural?

The most straightforward method is reading the fiber content label, which is legally required on all garments. Natural fibers include cotton, linen, hemp, silk, wool, cashmere, alpaca, and jute. Semi-synthetic fibers derived from natural cellulose include Tencel (lyocell), modal, viscose, and rayon. Fully synthetic fibers like polyester, nylon, and acrylic are petroleum-based and not natural. If the label lists a blend, add up the natural fiber percentages to see what proportion of the garment is genuinely natural.

For a physical test at home, the burn test can be informative. Natural plant fibers like cotton and linen burn with a steady flame and leave soft ash. Protein fibers like silk and wool smell like burning hair and leave a crushable bead. Synthetics melt, drip, and leave a hard plastic bead. However, this test should be used cautiously and only on a small thread or swatch, as blends can give mixed results.

ONDU simplifies the verification process by doing the research for you. Every product on our platform has been reviewed for its fiber content, and we provide a clear breakdown on each listing. We also include information about certifications like GOTS, OEKO-TEX, and bluesign that independently verify natural and organic claims.