Hair Care and Treatment: Shampooing, Conditioning, and Scalp Care
Analyze before you lather
Every shampoo starts with a hair-and-scalp analysis: texture (fine, medium, coarse), density, porosity (how readily hair takes in moisture), elasticity (wet hair stretched should return, not snap), and scalp condition (normal, oily, dry, flaking). Porosity and elasticity tell you whether chemical services are safe later; the scalp tells you which shampoo fits now.
pH is the backbone concept
Hair and skin sit on the acid side, about pH 4.5-5.5. The scale runs 0-14 with 7 neutral, and each whole number is a tenfold change. Below 7 is acidic (tightens the cuticle, adds shine); above 7 is alkaline (swells hair, lifts the cuticle, cleans aggressively). Acid-balanced and sulfate-free shampoos suit color-treated and porous hair; clarifying shampoos are alkaline and used sparingly; medicated shampoos are for diagnosed scalp conditions, not casual use.
Conditioning types
Surface conditioners smooth the cuticle and rinse out; penetrating conditioners work into the cortex; protein conditioners temporarily fill damaged areas. Apply from mid-shaft to ends, not to a healthy scalp, unless the product is made for scalp use. Water should be comfortably warm, never hot, because heat swells the cuticle and speeds color fade.
Traps
Questions love to swap acidic and alkaline, blame hot water on nothing, or suggest vigorous scalp massage on a client with abrasions, sunburn, or a contagious condition, which is contraindicated.
Rule of thumb
Client with highlighted, high-porosity hair: acid-balanced sulfate-free shampoo, lukewarm water, conditioner mid-shaft to ends, cool rinse to close the cuticle.