Silk vs Polyester

Properly degummed silk is one of the most skin-friendly fibers you can wear. Its smooth filament structure and ability to manage moisture and temperature mean it breathes, wicks, and regulates heat against your skin, which lowers irritation and supports your skin barrier. The catch is residue: low-quality silk that keeps too much sericin can be read by your immune system as foreign and trigger histamine release and contact allergy, and the dyes and finishing agents layered on during manufacturing are a more common cause of allergic contact dermatitis than the fiber itself. If silk irritates you, suspect the finish, not the protein.

When polyester contacts your sweat, a fraction of that antimony mobilizes into the moisture against your skin; antimony trioxide is classified by IARC as a possible human carcinogen, and exposure rises in tight, warm activewear. Polyester is also the workhorse of disperse-dye allergy, the most common cause of textile contact dermatitis, with the dye migrating onto skin worst where you sweat and rub. On top of that, polyester sheds microplastics onto your skin and into household air, and consumer testing has flagged bisphenol A (an endocrine disruptor) in polyester athletic wear at many times the safe limit. The dose from any one garment is small, but you wear it constantly and sweat into it.