Alkalinity reduces skin barrier tolerance

This hypothesis asks whether washing and friction leave skin less able to resist later challenge, with implications for middle-aged skin. Washing may make outer skin less acidic. During a longer alkaline interval, serine proteases, protein-cutting enzymes, could cleave lipid-processing enzymes that organize fats. The prediction is lower enzyme activity and enzyme fragments with lower barrier tolerance after identical washing and friction. Testing would use tissue-like lab skin and isolated outer layers, matching hydration and acidity before a final challenge. Early protease inhibition should preserve tolerance; later inhibition could leave it impaired. These paired measures could distinguish persistent enzyme loss from temporary repair or energy availability.