Hair and Scalp Care, Shampooing, and Treatments
Structure and Growth
The hair shaft has three layers: cuticle (protection), cortex (strength, pigment, moisture), and medulla (innermost, often absent in fine hair). The follicle anchors hair with the sebaceous gland and arrector pili muscle. Hair grows in cycles - anagen (growth), catagen (transition), and telogen (rest) - with roughly 90 percent in anagen and normal shedding around 50-100 hairs daily. Bond types matter chemically: disulfide bonds give strength and shape, hydrogen and salt bonds break with water and pH, and peptide bonds break with extreme damage.
Scalp Conditions and Contraindications
Recognize pityriasis (dry or oily flaking), seborrheic dermatitis, psoriasis, tinea (ringworm - contagious, refer out), and pediculosis (lice - refer out). Inflammation, open lesions, and suspected infection are contraindications to chemical services and aggressive massage. Medicated shampoos manage, not cure, and a cosmetologist does not diagnose.
Shampooing and Treatments
Shampoo surfactants lift oil and debris; conditioner deposits cationic ingredients that smooth the cuticle and reduce static. Match shampoo to scalp and hair condition, use lukewarm water, and protect the client's eyes and clothing with proper draping. Scalp massage increases circulation and relaxation but is contraindicated over inflammation. Protein treatments temporarily fill gaps in porous hair; moisturizing treatments restore softness and elasticity. Always follow with a thorough rinse, and towel-dry gently.
Traps and Rule of Thumb
Watch for 'dandruff is contagious,' 'medicated shampoo cures seborrheic dermatitis,' and 'hot water improves shine.' Rule of thumb: if the scalp is red, broken, or itchy with flakes that look fungal, do not treat - refer, and perform no chemical service.