Chemistry, Product Knowledge, and Product Safety
Core concepts
Matter is made of atoms, elements, and compounds. Know the difference between a solution (evenly mixed, will not settle), a suspension (particles settle, must be shaken), and an emulsion (two immiscible liquids held together by an emulsifier - most lotions and creams).
The pH scale runs 0-14 with 7 neutral. Hair and skin sit around 4.5-5.5 thanks to the acid mantle. Alkaline products swell and open the cuticle; acidic products shrink and close it. Shampoos rely on surfactants with a hydrophilic head and lipophilic tail.
Bonds: hydrogen bonds are broken by water (this is why wet sets work), salt bonds by pH change, disulfide bonds by perms and relaxers (and re-formed by neutralizer), plus peptide and van der Waals forces.
Oxidation (peroxide, lightener) removes electrons; reduction (ammonium thioglycolate) adds them. Developers: 10 volume = 3% peroxide, 20 volume = 6%, 30 volume = 9%, 40 volume = 12%. Gels and acrylics form polymers from monomers.
Traps
- Reading pH as 'strength' - pH measures acidity, not lifting power.
- Forgetting that exothermic products release heat on mixing.
- Storing chemicals in unlabeled containers or mixing brands.
- Ignoring SDS sheets, ventilation, gloves, and the ban on eating or drinking at the station.
Rule of thumb
Alkaline opens and swells; acid closes and firms - use that one sentence to reason through shampoo, perm, relaxer, and color questions.