1. Low porosity hair has tightly compacted cuticles that resist water and product entry, so it wets slowly and products bead on the surface. Normal porosity absorbs and releases moisture more readily, while high porosity takes in water fast but loses it quickly due to lifted or damaged cuticles. 2. The cuticle plates overlap like shingles and are sealed with a hydrophobic lipid layer, leaving fewer pathways for water and conditioners to penetrate. Lower fiber swelling and fewer surface defects make absorption slower without gentle heat or prolonged contact time. 3. Common myths: it never needs protein, oils always fix dryness, and co-washing alone is enough. In reality, low porosity hair often needs small, periodic protein, lighter oils or esters, and regular cleansing to avoid buildup. 4. Proteins with low molecular weight can strengthen but should be used sparingly, about every 4 to 8 weeks, or when hair feels stretchy. Heavy oils and butters tend to sit on top; lighter options like squalane or jojoba esters absorb better. 5. Porosity can change with heat styling, chemical services, UV, aging, illness, and postpartum shifts. Repeated coloring or relaxers raise porosity; careful care and time can partially normalize feel but not fully reverse cuticle damage. 6. Cleanse weekly with a gentle shampoo, then deep condition 10 to 20 minutes with gentle heat or a cap. Use a lightweight leave-in on damp hair, seal ends with a few drops of a light oil, and protect at night with a satin bonnet or pillowcase. 7. Low porosity hair tolerates occasional heat if protected, but high temps can create bubbles and cracks in the cuticle. Keep tools under 300 to 320degF, use a heat protectant, limit passes, and avoid frequent chemical services that permanently raise porosity. 8. Works well: glycerin or propanediol in modest amounts, panthenol, amino acids, lightweight esters, squalane, and conditioners with behentrimonium or cetrimonium. Use caution with heavy waxes, thick butters, repeated large-molecule proteins, and heavy non-water-soluble silicones without routine clarifying. 9. High humidity can cause surface frizz if humectants are overused; choose balanced formulas and finish with a light sealant. Hard water deposits make hair dull and stiff; use a chelating or EDTA-containing shampoo monthly and consider a shower filter. 10. Early signs of buildup include water beading, very long drying times, dullness, and products that sit white on strands.