Chemistry, Product Knowledge, and Implements/Tools
Chemistry, Product Knowledge, and Implements/Tools
This domain tests pH, the types of mixtures you handle, and how to choose and maintain tools.
Core rules
- pH runs 0-14 and is logarithmic: each whole step is a tenfold change. Hair is about 4.5-5.5, skin about 5.5, and relaxers 9-13.
- Acids donate hydrogen ions; bases accept them. Strong alkalinity swells and roughens hair; acids tighten the cuticle.
- Mixtures: solutions (evenly dissolved), suspensions (particles settle out), emulsions (oil and water held together by an emulsifier), and ointments.
- Surfactants have a water-loving head and an oil-loving tail; they lift sebum so water can rinse it away.
- Oxidation adds oxygen (lighteners, tints); reduction removes it (relaxers, waves). Neutralizers stop both.
- Tools: stainless steel resists rust; carbon steel holds an edge but rusts; shears must be kept dry and oiled. Combs should be seamless and disinfected between clients.
Worked example
A label says a product has a pH of 3. Reasoning: that is ten times more acidic than pH 4 and 100 times more acidic than pH 5. You use it as a cuticle-smoothing product for high-porosity hair and keep it away from the eyes.
Traps
- pH 7 is neutral; "pH-balanced" does not mean pH 7.
- Mixing products can create heat or gas; never combine bleach and ammonia.
- Ointments are not emulsions.
- Hard water minerals reduce lather and can dull color; clarify when appropriate.