Mercerized Cotton

Mercerization treats cotton yarn or fabric under tension with a caustic solution, swelling the fibers to boost luster, strength, and dye absorption. The result is a subtle sheen and richer color, common on dress-shirt cotton and finer polos. It is a legitimate finishing process, not a gimmick, but it is cosmetic-plus-durability rather than transformative. On a spec sheet it helps explain why one cotton shirt looks crisper and holds color better than another of similar weight. As always, the finish rides on the base yarn — mercerized carded cotton is still carded cotton underneath.