Knix's Seamless Invisible Cotton Underwear Took 18 Months and 31 Prototypes

The intimates brand released Invisible Cotton last week, capping a multi-year push by its design team to build a cotton underwear range that disappears under clothing without the seams shoppers are used to seeing.

Jules Power, vice president of design at Knix, oversees underwear, bras and swimwear, and said one of the hardest parts of working in intimates is engineering pieces that stay comfortable through a full day. A poorly made pair of underwear, she noted, is something the wearer notices immediately.

Knix was founded in 2012 around leak-proof underwear, and Power described seamlessness — product that sits close to the body and reads as invisible beneath clothes — as central to the brand's identity. Extending that promise to cotton was far more difficult than the finished garment suggests.

Getting a seamless cotton line to market had been an obsession for Power and her team for several years, and the effort ultimately ran to 18 months of work, 31 prototypes and 1,700 hours of wear testing before the collection was ready.

Much of Knix's output relies on bonding, a heat-seal process that fuses layers of fabric together rather than stitching them, a technique that supports the smooth, seam-free construction the brand is known for.