Cosmetology Chemistry & Electricity
The products and machines used in the salon are applied chemistry and physics. This chapter covers the basics of matter and mixtures, the pH scale, and the electrical currents used safely in salon treatments.
Matter, Mixtures, and Emulsions
Matter exists as elements, compounds, and mixtures. Many salon products are emulsions — physical mixtures of two immiscible liquids (usually oil and water) held together by an emulsifier that keeps tiny droplets suspended; creams, lotions, and conditioners are common examples, formulated as oil-in-water or water-in-oil. A solution, by contrast, is a stable, uniform blend of a solute dissolved in a solvent. Understanding these categories explains why products separate, mix, or behave as they do.
The pH Scale in Cosmetology
pH measures how acidic or alkaline a water-based solution is, on a scale of 0 to 14 with 7 neutral. The scale is logarithmic: each whole-number step is a tenfold change, so a move from pH 6 to pH 4 is 100 times more acidic. Alkaline products swell and open the hair and skin (used in colors, lighteners, and cold waves), while acidic products contract and smooth them (used in many conditioners and toners). Knowing pH helps you predict a product's effect.
Electricity in the Salon
Several currents are used in salon electrotherapy, where permitted. Galvanic current is a constant, direct current used to create chemical and ionic effects in the skin (desincrustation and iontophoresis). Faradic current is an alternating, interrupted current used to cause muscle contractions for toning. High-frequency (Tesla) current is used for its stimulating and germicidal effects. Always follow safety rules: inspect cords, avoid water hazards, and use modalities only as trained and allowed.