Meaning ❉ Transepidermal Water Loss, often known as TEWL, describes the quiet, continuous diffusion of water vapor from the skin’s surface and, significantly for textured hair, from the hair shaft itself. This delicate yet persistent osmotic process influences the hydro-lipid barrier’s integrity, directly impacting scalp comfort and strand flexibility. For coils, curls, and waves, where the unique structural configuration naturally presents more surface area and a less tightly sealed cuticle, this subtle water egress becomes a primary consideration in maintaining suppleness and strength. Understanding TEWL is the foundational step in comprehending why Black and mixed-heritage hair often feels thirsty, guiding one towards a more intuitive grasp of dryness beyond mere sensation. It informs the precise systematization of a hair care approach, allowing for intentional layering of humectants to draw in atmospheric moisture, followed by emollients and occlusives that gently seal the cuticle, minimizing the vapor’s departure. This knowledge transforms daily rituals into a purposeful science, ensuring each strand retains its vital hydration, promoting resilient growth and a vibrant appearance.
