Salon Chemistry Essentials

The Science Behind Every Salon Product

An open beauty school cosmetology kit with scisso

Foundations | State Board Exam Aligned

Shear Genius Society Curriculum

Chemistry is behind

Every Product You Touch

in the salon

Nail polish • Acrylics • Gels • Shampoo • Color • Disinfectants

Understanding chemistry = understanding WHY products work.

What You'll Learn

Define matter, elements, compounds, and molecules
Identify the three states of matter and their properties
Explain the pH scale and its importance in salon products
Distinguish between solutions, suspensions, and emulsions

What You'll Learn

continued

Understand oxidation-reduction reactions in salon services
Explain how nail products cure and polymerize
Identify chemical safety protocols for the salon
Apply chemistry knowledge to State Board exam questions

SECTION 01

Matter & Elements

The Building Blocks of Everything

What Is Matter?

EVERYTHING YOU CAN TOUCH, SEE, OR SMELL

Matter is anything that occupies space and has mass.

Atoms

The smallest unit of an element — cannot be broken down further

Elements

The simplest form of matter — made of one type of atom (e.g., oxygen, carbon)

Compounds

Two or more elements chemically combined (e.g., water = H₂O)

Molecules

Two or more atoms bonded together — the smallest unit of a compound

States of Matter

THREE FORMS — SOLID, LIQUID, GAS

SOLID

Fixed shape, fixed volume. Molecules are tightly packed.

Examples: nail file, metal tools, wax

LIQUID

Fixed volume, takes shape of its container. Molecules flow freely.

Examples: water, polish, acetone

GAS

No fixed shape, no fixed volume. Molecules spread out.

Examples: oxygen, fumes from nail products

Physical vs Chemical Properties

PHYSICAL PROPERTIES

Can be observed WITHOUT changing the substance

Color, size, shape, odor
Density and boiling point
Melting wax = physical change
Dissolving salt in water

CHEMICAL PROPERTIES

Change the identity of the substance — NEW substance formed

Flammability, reactivity
Oxidation (rusting, color processing)
Hair color = chemical change
Acrylic curing = chemical change

Changes in Matter

KNOW THE DIFFERENCE FOR YOUR EXAM

Physical Change

No new substance formed — can often be reversed

Examples: Ice melting, cutting hair, evaporating acetone

Chemical Change

New substance IS formed — usually cannot be reversed

Examples: Hair coloring, acrylic curing, perming, neutralizing

BOARD TIP: If a NEW substance forms, it is a chemical change. If not, it is physical.

SECTION 02

Chemistry of Water

The Universal Solvent • pH Scale • Salon Applications

Water: The Universal Solvent

THE MOST IMPORTANT CHEMICAL IN THE SALON

Water dissolves more substances than any other liquid
Chemical formula: H₂O (2 hydrogen atoms + 1 oxygen atom)
Water is essential for mixing, rinsing, and diluting products
Pure water has a neutral pH of 7.0
Water makes up 50-70% of the human body

The pH Scale

MEASURES ACIDITY vs ALKALINITY — 0 TO 14

0 – 6.9

ACIDIC

Below 7 on the pH scale

7.0

NEUTRAL

Pure water — right in the middle

7.1 – 14

ALKALINE

Above 7 on the pH scale

Each step on the pH scale is 10x stronger than the one before it.

A pH of 3 is 10 times more acidic than a pH of 4, and 100 times more acidic than a pH of 5.

BOARD TIP: Hair and skin have a natural pH of 4.5 - 5.5 (slightly acidic).

pH of Common Salon Products

WHERE THEY FALL ON THE SCALE

Lemon juice / Acid rinse

pH 2-3 — Closes cuticle, adds shine

Hair & skin (natural)

pH 4.5-5.5 — The acid mantle protects skin

Pure water (neutral)

pH 7.0 — The midpoint of the scale

Shampoo

pH 4.5-5.5 — Acid-balanced to match hair/skin

Permanent wave solution

pH 9-10 — Alkaline — breaks disulfide bonds

Hair relaxer / Bleach

pH 10-13 — Highly alkaline — extreme caution!

Soft vs Hard Water

AFFECTS PRODUCT PERFORMANCE IN THE SALON

SOFT WATER

Low mineral content
Lathers easily with soap
Rinses cleanly — no residue
Better for salon services

HARD WATER

High calcium & magnesium
Reduces lather — uses more product
Leaves mineral buildup on hair
Can affect color results

Many salons install water softeners to ensure consistent product results.

SECTION 03

Chemistry of Products

Solutions • Suspensions • Emulsions • Surfactants

Three Types of Mixtures

HOW SALON PRODUCTS ARE FORMULATED

SOLUTION

Solute is completely dissolved in a solvent. Will NOT separate. Clear or transparent.

Salt water, hydrogen peroxide, nail polish remover (acetone)

SUSPENSION

Particles are mixed but NOT dissolved. Will separate over time — must shake.

Calamine lotion, some medicated shampoos

EMULSION

Two unmixable liquids held together by an emulsifier. Oil + water combination.

Conditioner, lotions, creams, mayonnaise

Two Types of Emulsions

OIL-IN-WATER vs WATER-IN-OIL

OIL-IN-WATER (O/W)

Oil droplets dispersed IN water

Lighter, non-greasy feel
Rinses off easily with water
Most lotions and conditioners
Majority of salon products

WATER-IN-OIL (W/O)

Water droplets dispersed IN oil

Heavier, more moisturizing
Water-resistant — stays on skin
Cold creams, sunscreens
Protective barrier products

BOARD TIP: Most salon products are oil-in-water emulsions — they rinse away easily.

Surfactants

THE BRIDGE BETWEEN OIL AND WATER

Surfactants (surface active agents) allow oil and water to mix.

Hydrophilic Head

"Water-loving" end — attracts water molecules

Lipophilic Tail

"Oil-loving" end — attracts oil and dirt

How It Works

The tail grabs oil/dirt, the head pulls it into water for rinsing

How Salon Products Work

CHEMISTRY IN ACTION

Shampoo

Surfactants lift oil + dirt from hair — rinsed with water

Conditioner

O/W emulsion coats hair cuticle — smooths, adds moisture

Nail Polish

Solution of nitrocellulose in solvents — dries by evaporation

Gel Polish

Photoinitiators react to UV/LED light — cures by polymerization

Acrylic Nails

Monomer + polymer = exothermic reaction — hardens into enhancement

SECTION 04

Oxidation-Reduction

Redox Reactions • Hair Color • Nail Product Curing

Oxidation-Reduction (Redox)

TWO REACTIONS THAT ALWAYS HAPPEN TOGETHER

OXIDATION

Adding oxygen to a substance
OR removing hydrogen
Causes a chemical change

REDUCTION

Removing oxygen from a substance
OR adding hydrogen
The opposite of oxidation

Remember: You cannot have one without the other. They occur simultaneously.

BOARD TIP: "OIL RIG" — Oxidation Is Loss, Reduction Is Gain (of electrons).

Redox Reactions in the Salon

WHERE YOU'LL SEE THIS EVERY DAY

Hair Color

Developer (hydrogen peroxide) oxidizes melanin and deposits color

Most common redox reaction in the salon

Hair Lightening

Peroxide oxidizes melanin — breaks it down to lighten hair

The stronger the developer, the more lift

Permanent Waves

Waving lotion reduces disulfide bonds — neutralizer re-oxidizes them

Reduction breaks bonds, oxidation reforms them

Disinfection

Oxidizing agents kill bacteria and viruses

Hydrogen peroxide and bleach are oxidizing disinfectants

Curing & Polymerization

HOW NAIL PRODUCTS HARDEN

Polymerization = small molecules (monomers) join to form large chains (polymers).

1

ACRYLICMonomer liquid + polymer powder = exothermic reaction — releases heat

2

UV/LED GELPhotoinitiators absorb light energy — triggers polymerization

3

NAIL POLISHSolvents evaporate — film-forming polymers dry into a hard coat

Exothermic = gives off heat. Clients may feel warmth during acrylic application.

Exothermic vs Endothermic

HEAT IN CHEMICAL REACTIONS

EXOTHERMIC

Releases heat energy

Acrylic nail application
Hair color processing
Feels warm to the touch

ENDOTHERMIC

Absorbs heat energy

Cold packs (first aid)
Some chemical peels
Feels cool to the touch

If a client complains of excessive heat during acrylic application,

the product was applied too thickly — creating too much exothermic reaction.

SECTION 05

Chemistry in Nail Technology

Monomers • Polymers • Photoinitiators • Solvents • Safety

Monomers & Polymers

THE BUILDING BLOCKS OF NAIL ENHANCEMENTS

Mono = one | Poly = many | Mer = unit

Monomer

A single molecule — the liquid in acrylic systems. Individual units that can link together.

Polymer

A chain of monomers bonded together — the powder in acrylic systems. The hardened, finished product.

Polymerization

The chemical reaction that joins monomers into polymer chains. Triggered by a catalyst (initiator or light).

How Acrylics Work

LIQUID + POWDER = ENHANCEMENT

1

DIPBrush dipped in monomer liquid (ethyl methacrylate)

2

PICK UPBrush picks up polymer powder — forms a bead

3

PLACEBead placed on nail — shaped with brush while workable

4

CURECatalyst in powder triggers polymerization — exothermic reaction

5

HARDENMonomer chains link into solid polymer — strong nail enhancement

Photoinitiators & UV/LED Gels

HOW GEL POLISH CURES

Gels contain photoinitiators — chemicals that react to specific wavelengths of light.

UV Lamps

Broad spectrum ultraviolet light — cures most gel types in 2 min

LED Lamps

Narrow wavelength (405nm) — faster cure, 30-60 seconds

Photoinitiator

Absorbs light energy and triggers polymerization chain reaction

Under-curing

Product not hard enough — lifting, peeling, allergic reactions

Over-curing

Excessive heat — burning sensation, brittle product

Adhesion vs Cohesion

WHY PRODUCTS STICK — OR DON'T

ADHESION

Bonding between TWO DIFFERENT surfaces

Nail enhancement to natural nail
Polish to nail plate
Primer improves adhesion

COHESION

Bonding within THE SAME substance

Acrylic holding itself together
Gel layers bonding to each other
Internal strength of the product

Lifting = adhesion failure. Cracking = cohesion failure.

Solvents in Nail Technology

WHAT DISSOLVES WHAT

Acetone

Strongest common solvent — dissolves nail polish, acrylics, gel polish

Fast-acting but very drying to skin and nails

Non-Acetone Remover

Ethyl acetate based — gentler alternative to acetone

Slower to dissolve polish, less drying

Alcohol (Isopropyl)

Disinfectant and dehydrator — used in nail prep

Removes oils from nail plate before service

Nail Polish Thinner

Restores consistency to thickened polish

NEVER use remover as thinner — it breaks down the product

Safety Data Sheets (SDS)

FORMERLY CALLED MSDS — KNOW YOUR PRODUCTS

Every professional product must have an SDS on file
Contains 16 sections of safety and hazard information
Lists ingredients, hazards, first aid, storage, and disposal
Must be accessible to ALL employees at all times
Provided free by the manufacturer upon request

BOARD TIP: SDS sheets must be available in the salon — this is a legal requirement.

SECTION 06

Chemical Safety

Ventilation • Storage • Mixing • First Aid • SDS

Ventilation Requirements

PROTECT YOURSELF AND YOUR CLIENTS

Work in well-ventilated areas — open air flow is essential
Use a local exhaust ventilation system at your station
Table-top ventilation fans pull fumes AWAY from your breathing zone
Never work in a closed room with acrylic or gel products
Replace ventilation filters regularly per manufacturer guidelines

Proper Chemical Storage

FOLLOW THESE RULES — NO EXCEPTIONS

1

COOL & DRYStore all chemicals away from heat, sunlight, and moisture

2

SEALEDKeep all containers tightly closed when not in use

3

LABELEDEvery container must be clearly labeled — no unmarked bottles

4

ORIGINALKeep products in original containers — never transfer to food containers

5

SEPARATEDStore oxidizers away from flammables — check SDS for compatibility

Chemical Mixing Rules

CRITICAL SAFETY — MEMORIZE THESE

NEVER mix chemicals together unless directed by the manufacturer
NEVER combine bleach with ammonia — produces toxic chloramine gas
NEVER add water to acid — always add acid to water
ALWAYS follow manufacturer mixing ratios exactly
ALWAYS read the SDS before using any new product

Improper mixing can cause fires, toxic fumes, or chemical burns!

First Aid for Chemical Exposure

KNOW HOW TO RESPOND IMMEDIATELY

Skin Contact

Remove contaminated clothing. Flush skin with cool water for 15+ minutes.

Eye Contact

Flush eyes with clean water for at least 15 minutes. Seek medical attention.

Inhalation

Move to fresh air immediately. If difficulty breathing, call emergency services.

Ingestion

Do NOT induce vomiting. Call Poison Control immediately. Read the SDS.

Chemical Burns

Flush with cool water — do NOT apply ointments. Cover with sterile bandage.

Key Terms Review

PART 1

Matter

Anything that has mass and occupies space

Element

Simplest form of matter — one type of atom only

Compound

Two or more elements chemically combined (e.g., H₂O)

pH Scale

Measures acidity (0-6.9) vs alkalinity (7.1-14) — 7 is neutral

Emulsion

Mixture of two unmixable liquids held together by an emulsifier

Key Terms Review

PART 2

Oxidation

Adding oxygen or losing hydrogen — causes chemical change

Reduction

Removing oxygen or adding hydrogen — opposite of oxidation

Monomer

Single molecule unit — the liquid in acrylic systems

Polymer

Chain of monomers bonded together — the solid product

SDS

Safety Data Sheet — 16 sections of chemical safety information

Board Exam Tips

CHEMISTRY EDITION

Memorize the pH scale — hair/skin is 4.5-5.5, water is 7.0
Know physical vs chemical change — if a NEW substance forms, it is chemical
Oxidation adds oxygen, Reduction removes it — remember OIL RIG
SDS sheets must be available in the salon — required by law
Acrylic = exothermic — monomer + polymer releases heat

Q1

What is the pH of pure water?

A) 4.5
B) 5.5
C) 7.0
D) 10.0

Click to reveal answer

Q2

Which type of change creates a NEW substance?

A) Physical change
B) Chemical change
C) Temporary change
D) Mechanical change

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Q3

What does a surfactant do?

A) Kills bacteria
B) Raises pH
C) Allows oil and water to mix
D) Hardens nail products

Click to reveal answer

Q4

What is the natural pH of hair and skin?

A) 2.0 - 3.0
B) 4.5 - 5.5
C) 7.0
D) 9.0 - 10.0

Click to reveal answer

Q5

What type of reaction occurs during acrylic nail application?

A) Endothermic
B) Nuclear
C) Exothermic
D) Enzymatic

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Q6

Which solvent is the strongest common nail product remover?

A) Water
B) Alcohol
C) Non-acetone remover
D) Acetone

Click to reveal answer

Q7

What does SDS stand for?

A) Salon Disinfection Standard
B) Safety Data Sheet
C) Solvent Dilution System
D) Sanitation Disposal Service

Click to reveal answer

Q8

An oil-in-water emulsion is:

A) Heavy and greasy
B) Water droplets in oil
C) Oil droplets dispersed in water
D) A type of solution

Click to reveal answer

Salon Chemistry Essentials

Chapter Complete

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