Chemistry & Electricity in Cosmetology

Chemistry & Electricity in Cosmetology

Cosmetology relies heavily on applied chemistry and physics. Every hair color application, permanent wave, chemical relaxer, and facial electrotherapy treatment is governed by scientific laws. A professional cosmetologist must master basic chemical composition, pH dynamics, surfactant systems, electrical measurement units, and safety protocols to protect clients from chemical burns or electrical shock.

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Cosmetic Chemistry Fundamentals

Chemistry is the science that deals with the composition, structures, and properties of matter and how matter changes under different conditions.

• Organic Chemistry: The study of substances containing the element carbon. All living or once-living things (plant, animal, hair, skin, synthetic plastics) contain carbon and are organic.
• Inorganic Chemistry: The study of substances that do not contain carbon (e.g., water, minerals, metals, air).

Matter and States of Matter

Matter is any substance that occupies space and has mass (weight). Matter exists in three physical states:

1. Solids: Have definite shape and definite volume (e.g., ice, hair shears, fingernails).
2. Liquids: Have definite volume but take the shape of their container (e.g., water, shampoo, hydrogen peroxide).
3. Gases: Have no definite shape or volume (e.g., steam, propellant gases, oxygen).

Physical vs. Chemical Changes

• Physical Properties: Characteristics determined without establishing a new chemical substance (e.g., color, odor, density, melting point).
• Physical Change: A change in the form or physical properties of a substance without a chemical reaction or creation of a new substance (e.g., ice melting to water, temporary hair styling with a curling iron).
• Chemical Change: A change in the chemical composition of a substance created by a chemical reaction, forming a new substance with entirely different properties (e.g., oxidation of hair color, perming, chemical relaxing).

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Solutions, Suspensions, and Emulsions

Cosmetic products are physical mixtures of two or more substances:

• Solution: A stable, uniform physical mixture of two or more substances dissolved in a solvent. Solute particles are tiny and will not settle out (e.g., salt water, hydrogen peroxide solution).
  • Solute: The dissolved substance.
  • Solvent: The liquid that dissolves the solute (water is the universal solvent).
• Suspension: An unstable physical mixture of undissolved particles in a liquid. Particles are visible, settle over time, and require shaking before use (e.g., calamine lotion, glitter nail polish).
• Emulsion: An unstable physical mixture of two or more immiscible (unmixable) liquids held together by a binder called an emulsifier (or surfactant). Emulsions separate slowly over time.

Surfactant Molecule Structure

Surfactants (Surface Active Agents) allow oil and water to mix. A surfactant molecule has two distinct ends:

• Hydrophilic Head: Water-loving end that dissolves readily in water.
• Lipophilic Tail: Oil-loving end that dissolves readily in oil and grease.

In an Oil-in-Water (O/W) Emulsion, oil droplets are emulsified in water (e.g., shampoos, lotions). In a Water-in-Oil (W/O) Emulsion, water droplets are emulsified in oil (e.g., cold creams, night creams).

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The pH Scale & Chemical Reactions

pH stands for Potential Hydrogen, measuring the concentration of hydrogen ions in a water-based solution. Only aqueous (water-containing) solutions have a pH.

• The pH scale ranges from 0 to 14.
• pH 7.0 is neutral (pure distilled water).
• Below 7.0 is acidic; Above 7.0 is alkaline.
• The pH scale is logarithmic: a change of 1 whole pH unit represents a 10-fold change in hydrogen ion concentration (e.g., pH 8 is 10 times more alkaline than pH 7, and 100 times more alkaline than pH 6).

NATURAL HAIR & SKIN pH: Natural hair, skin, and the acid mantle have a slightly acidic pH between 4.5 and 5.5. Acidic products (pH 3.0 to 5.5) shrink, harden, and close the hair cuticle. Alkaline products (pH 8.0 to 13.0) soften, swell, and open the cuticle for chemical processing.

Chemical Reactions: Oxidation-Reduction (Redox)

• Oxidation: A chemical reaction in which oxygen is added to a substance, or hydrogen is removed. Oxidation increases the oxidation state.
• Reduction: A chemical reaction in which oxygen is subtracted from a substance, or hydrogen is added.
• Redox Reaction: Oxidation and reduction occurring simultaneously (e.g., hydrogen peroxide releasing oxygen to oxidize tint molecules while oxidizing hair melanin).
• Exothermic Reactions: Chemical reactions that release heat (e.g., self-heating perm lotions).

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Electricity & Electrical Measurement Units

Electricity is a form of energy that produces magnetic, chemical, and thermal effects when in motion.

• Direct Current (DC): Constant, even-flowing current moving in one direction only (e.g., battery-operated clippers, flashlights).
• Alternating Current (AC): Rapid, interrupted current flowing first in one direction and then in the opposite direction (e.g., corded blow dryers, salon chairs plugged into wall outlets).

Electrical Measurement Terms

• Volt (V): Measures electrical pressure or force pushing current forward.
• Ampere (Amp / A): Measures current strength or volume of electron flow.
• Milliampere (mA): 1/1,000th of an Ampere; used in facial electrotherapy machines.
• Ohm (Ω): Measures electrical resistance to the flow of current.
• Watt (W): Measures total electrical power consumed per second (Volts x Amps = Watts).
• Kilowatt (kW): 1,000 Watts (salon electricity meters measure in kilowatt-hours).

Safety Devices

• Fuse: Safety device containing a fine wire that melts when current overloads the circuit.
• Circuit Breaker: Modern safety switch that automatically trips open when a circuit is overloaded.
• Ground Fault Circuit Interrupter (GFCI): Fast-acting circuit breaker required near water sources (sinks/pedicure tubs) that shuts off power instantly if moisture causes current leakage.

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Electrotherapy Modalities

Electrotherapy involves applying electrical currents to skin for therapeutic benefits:

1. Galvanic Current: A constant, direct current (DC) producing chemical and ionic changes:
   • Anaphoresis (Desincrustation): Uses the negative pole (cathode) to force alkaline products into skin, softening tissue, opening pores, and emulsifying sebum for deep extraction.
   • Cataphoresis (Iontophoresis): Uses the positive pole (anode) to force acidic products into skin, closing pores, soothing nerves, and tightening tissue.
2. Tesla High-Frequency Current (Thermal / Violet Ray): An alternating thermal current that produces heat without causing muscle contractions. Glass electrodes filled with neon gas (orange glow) or argon gas (violet glow) stimulate blood circulation, increase metabolism, and possess germicidal properties.

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Chemical & Electrical Comparison Table