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CHEMISTRY & CHEMICAL SAFETY – (Study Guide)
1. Understanding Chemistry in the Beauty Industry
Beauty professionals work with chemistry every day—both in the human body and in salon products.
Hair, skin, and nails are all made of chemicals.
Products such as creams, lotions, and makeup are chemical mixtures (natural or lab-made).
Why Study Chemistry:
To use professional products safely and effectively.
To troubleshoot chemical service problems.
To follow correct handling and safety procedures in the salon.
2. Basic Chemistry Terms
Chemistry: The science that studies the composition, structure, and properties of matter and how it changes.
Matter: Anything that occupies space and has mass. Exists as solids, liquids, or gases.
Energy: Does not occupy space or have mass (e.g., light, electricity).
3. Physical vs. Chemical Changes
Physical Change: Alters appearance, not composition.
Example: Ice melting, polish drying.Chemical Change: Alters chemical composition and forms a new substance.
Example: Acid + Alkaline = Water (neutralization).
4. Physical vs. Chemical Properties
Physical Properties: Can be observed without changing the substance.
Examples: Color, odor, density, melting/boiling point, hardness, gloss.Chemical Properties: Can only be determined by chemical reactions.
Examples: Iron rusting, wood burning, hair changing color.
5. Types of Mixtures
Most salon products are physical mixtures:
| Type | Description | Examples |
|---|---|---|
| Solution | Stable mixture where one substance dissolves into another. | Salt water, witch hazel. |
| Suspension | Unstable mixture with visible particles that may settle. | Nail polish with glitter, lotions. |
| Emulsion | Unstable mixture of immiscible liquids held together by an emulsifier. | Creams, shampoos, conditioners. |
Key Terms:
Solute: Substance dissolved.
Solvent: Substance that dissolves the solute.
Miscible: Liquids that mix easily (water + alcohol).
Immiscible: Liquids that don’t mix (oil + water).
Surfactant: Ingredient that allows oil and water to mix.
6. The Overexposure Principle
Everything can be toxic at some level. “Non-toxic” is just a marketing term.
Overexposure: Repeated or long-term contact that causes sensitivity.
Toxicity depends on amount and exposure.
Example: Salt water is toxic if you drink it, safe to swim in it.
7. Understanding pH and Hydrogen Potential
pH = potential Hydrogen, measuring the balance of acidity and alkalinity.
Only water-based products have a pH value.
Key Concepts:
Ion: Atom or molecule with a charge.
Ionization: Splitting into positive (cation) and negative (anion) ions.
Hydrogen ions (H⁺): Acidic.
Hydroxide ions (OH⁻): Alkaline.
pH Scale (0–14):
7 = Neutral (pure water).
Below 7 = Acidic, Above 7 = Alkaline.
Each step = 10× difference in strength.
Example: pH 9 is 100× more alkaline than pH 7.Hair & Skin: Around pH 5 (slightly acidic).
Balance Examples:
Dry skin → avoid products too acidic.
Oily skin → use slightly acidic products to prevent acne.
8. Chemical Reactions
Neutralization: Acid + Alkaline = Water (balances pH).
Redox (Oxidation-Reduction):
Oxidation = adding oxygen (rusting, browning banana).
Reduction = removing oxygen (extinguishing a candle).
Exothermic Reaction: Releases heat (nail product hardening).
Endothermic Reaction: Absorbs heat (ice melting).
Combustion: Rapid oxidation producing heat and light (lighting a match).
9. Chemical Safety Practices
Labels
Regulated by EPA and FDA.
Must list hazards, ingredients, directions, and warnings.
Example: Hydrogen peroxide in high concentration causes burns.
Transportation
Some products are heat-sensitive or incompatible with others.
Example: Do not store above 78°F;
Hydrogen peroxide + bleach = toxic chlorine gas.
Storage
Keep all chemicals locked, labeled, and in original containers.
Store away from heat and sunlight.
Keep out of children’s reach.
Mixing
Always mix chemicals in ventilated areas using protective gear.
Follow label directions and use measuring tools.
Always add chemical to water, not water to chemical.
Disposal
Never pour chemicals down the sink.
Follow manufacturer instructions for safe disposal.
10. Summary
Chemistry is essential for understanding how products work on hair, skin, and nails.
Recognizing physical vs. chemical changes and maintaining safe practices prevents injury and ensures professional service quality.
Proper pH balance, chemical knowledge, and safety awareness protect both technician and client.