Routine cleansing usually targets only the top layer of "paint" (sebum-sweat film), not the "wall" (stratum corneum). Nevertheless, friction while cleansing could damage this barrier itself. Principle 2 is: avoid excess friction. Marketers might insist exfoliation is necessary, but here's the thing: daily cleanses for your face or body obviate additional exfoliation. Do not exfoliate dry or sensitive skin altogether. Frictional sources include: body scrubbing, facial exfoliation and towel drying. Body Scrubbing In Northeast Chinese bathhouses, not unlike shared scrub routines, perceived comfort objectively injures the stratum corneum. The surface dirt is already removed with normal washing — a loofah or scrub glove additionally removes functional layers of the stratum corneum; and undermines barrier functions. The skin will replace itself in 28 days, that much is true; however, during this repair phase the barrier remains impaired. If scrubbing seems inevitable: — Use a milk lubricant. — Choose soft towels — Be gentle. Restrict to once in 2–4 weeks. Facial Exfoliation A daily cleanse suffices. Stay clear of grainy scrubs and chemical exfoliants such as AHAs/BHAs. Those with oily or mature skin, accustomed to exfoliation — limit it once every 2–4 weeks. Drying Techniques Naturally drying depletes skin of its moisture, so gently pat dry. But even soft towels are best blotted rapidly to reduce friction. Towels & Hygiene — Every 3 days, wash towels. — Change every 3 months. — After each use, dry thoroughly to avoid bacterial growth. Back in high school: several male classmates struggled with acne — commonly due to using shared and unwashed towels. Disposable face towels, if towel hygiene proves difficult are safer.