Hair Colouring and Lightening

Chapter Objectives

This chapter covers the full range of theoretical and practical knowledge required for the Red Seal exam in hairstyling, specifically on hair colouring and lightening. You will find the fundamental chemical principles, application procedures, mixing calculations, safety standards applicable in Canada, as well as common pitfalls to avoid on the exam.

Fundamental Principles of Hair Colouring

Hair Structure and Its Role in Colouring

To understand colouring, you must first master the anatomy of the hair. The hair has three main layers:

The cuticle: outer layer made of overlapping cells (scales). It controls the penetration of colourants. A healthy, closed cuticle resists penetration; a lifted cuticle (by alkali or heat) allows pigment penetration.

The cortex: middle layer, home of melanin (natural pigment). This is where all colouring and lightening reactions occur.

The medulla: central layer, generally absent in fine hair. It has no direct role in colouring.

Melanin: Types and Distribution

Natural hair colour is determined by two types of melanin:

Type of Melanin	Colour	Characteristics
Eumelanin	Brown to black	Dense granules, resistant to lightening
Pheomelanin	Blonde to red	Smaller granules, less resistant

The proportion and density of these melanins vary according to hair type. Black hair contains mainly eumelanin in high density; blonde hair contains mostly pheomelanin in low density. This distinction is crucial for determining processing time and oxidant concentration.

Classification of Colourants

The most recognized classification system in Canada for the Red Seal exam distinguishes five categories of colourants:

Category	Common Name	Molecule	Penetration	Action
1. Temporary	Rinse colour	Acidic, large molecular weight	Cuticle only	Surface deposit, disappears after 1st shampoo
2. Semi-permanent	Ammonia-free	Small molecules	Partial cortex	Deposit without lightening, lasts 4 to 8 shampoos
3. Demi-permanent	Toner on toner	Small molecules + low-volume oxidant (10 volume)	Cortex	Deposit + slight oxidation, lasts 12 to 24 shampoos
4. Permanent (oxidation)	Permanent colour	Precursors + couplers + oxidant (20, 30, 40 volume)	Full cortex	Simultaneous lightening + deposit, permanent
5. Lightener	Bleach	Powder or cream + oxidant (20 to 40 volume)	Cortex	Destruction of melanin, permanent lightening

Key point for the exam: permanent colour does not "paint" the hair; it creates a chemical reaction in the cortex. The precursors (para-phenylenediamine or PPD, para-toluenediamine or PTD) penetrate the cortex, then the oxidant (hydrogen peroxide) triggers polymerization: the molecules bond to form large colour molecules that remain trapped in the cortex.

The Oxidant: Hydrogen Peroxide

Roles of Hydrogen Peroxide (H₂O₂)

Hydrogen peroxide has two essential functions:

22.Lightening natural melanin: it oxidizes (breaks down) melanin granules, reducing their opacity.

23.Developing colourants: it oxidizes colourless precursors to form colour molecules.

Concentrations and Volumes

Peroxide concentration is expressed in volumes (Canadian notation) or percentage (European notation). The following table should be memorized:

Volume	H₂O₂ Percentage	Lightening	Primary Use
5 volume	1.5%	0 to 0.5 levels	Toner on toner, refreshing tones
10 volume	3%	0 to 1 level	Deposit without lightening, toner on toner
20 volume	6%	1 to 2 levels	Standard permanent colourations
30 volume	9%	2 to 3 levels	More pronounced lightening, covering resistant hair
40 volume	12%	3 to 4 levels	Bleaching, maximum lightening

Golden rule: never exceed 40 volume on the scalp. Beyond this, there is a risk of chemical burns and irreversible hair damage.

Mixing Calculations

For the exam, you must know how to calculate colourant and oxidant quantities. The general rule for permanent colourations is a 1:1 ratio (one part colour to one part oxidant). For bleaching, the ratio is often 1:2 (one part powder to two parts oxidant), but always check the manufacturer's instructions.

Calculation example: a client has medium-length hair (approximately 150 g of hair). You prepare a permanent colouration with a 1:1 ratio. You will need 75 g of colour and 75 g of oxidant, for a total of 150 g of mixture.

Dilution formula: if you need to reduce the concentration of an oxidant, use the formula:

C₁ × V₁ = C₂ × V₂

Where C₁ = initial concentration (in volumes), V₁ = initial volume, C₂ = final concentration, V₂ = final volume.

Example: you have 40 volume peroxide and you want 30 mL of 20 volume peroxide.

40 × V₁ = 20 × 30

V₁ = (20 × 30) / 40 = 15 mL of 40 volume peroxide

Complete with 15 mL of distilled water (or saline solution) to obtain 30 mL at 20 volume.

Caution: never dilute with tap water (which contains minerals that can interfere with the reaction). Use distilled water.

The Colour Wheel and Colour Theory

Basic Principles

The colour wheel is an essential tool for neutralizing unwanted tones. Opposite colours on the wheel neutralize each other.

Colour to Neutralize	Neutralizing Colour
Yellow	Violet
Orange	Blue
Red	Green
Green	Red
Blue	Orange
Violet	Yellow

Practical application: a client with lightened hair has an unwanted yellow tone. You apply a toner on toner with violet pigments (or a violet shampoo) to neutralize the yellow.

Tones and Their Notation

Colourations carry an international numerical code. The first digit indicates the depth level, the following digits indicate the tones.

Depth Level	Level	Base Colour
1	Blue-black	Darkest
2	Black	Very dark
3	Dark brown	Dark
4	Brown	Medium
5	Light brown	Light
6	Dark blonde	Dark
7	Blonde	Medium
8	Light blonde	Light
9	Very light blonde	Very light
10	Platinum blonde	Lightest

Common tones: 1 = ash (blue/violet), 2 = iridescent (violet), 3 = golden (yellow), 4 = copper (orange), 5 = mahogany (red), 6 = red, 7 = green (rarely used alone).

Rule of 10 levels: each depth level corresponds to a scale from 1 to 10. One level of lightening corresponds to one depth level. For example, going from level 4 (brown) to level 7 (blonde) requires 3 levels of lightening.

Application Procedures

Preparation and Preliminary Tests

Before any colouring service, you must perform:

52.Skin sensitivity test (patch test): apply a small amount of colourant behind the ear or in the elbow crease, 24 to 48 hours before the service. Mandatory for new clients or if the product has changed.

53.Strand test: take a small section of hair to verify processing time and expected result. Particularly important for bleaching.

54.Porosity test: run a finger over a dry strand. If the cuticles are lifted (rough surface), porosity is high and processing time should be reduced.

55.Scalp examination: check for the absence of lesions, cuts, irritations, or conditions. Never apply colourant to a damaged scalp.

Applying Permanent Colour

Step 1: Client Preparation

Wrap the client in a protective cape.

Apply a protective barrier (cream) around the hairline, ears, and nape to prevent staining.

Wear nitrile gloves (never latex with certain products).

Step 2: Mixture Preparation

Mix the colour and oxidant in a non-metallic bowl (metal can oxidize the mixture).

Use a scale or graduated tubes to respect the ratio.

Mix until a homogeneous consistency is achieved.

Step 3: Application

Divide the hair into four sections (two diagonal: from the left ear to the crown, from the right ear to the crown, then two horizontal).

Apply the colour to the roots first (the heat of the scalp accelerates the reaction), then to the mid-lengths and ends.

For root touch-ups: apply only to the new growth, then to the mid-lengths and ends in the last 5 to 10 minutes.

Step 4: Processing Time

Respect the time indicated by the manufacturer (generally 30 to 45 minutes).

Monitor the progression: the colour must reach the desired depth level.

Step 5: Rinsing and Shampooing

Rinse thoroughly with lukewarm water until the water runs clear.

Apply a neutral shampoo (pH balanced) to remove residue.

Apply a conditioner or acidic treatment to close the cuticles.

Applying Bleach

Bleaching is more aggressive than permanent colour. It requires special attention:

78.Choosing the concentration: 20 volume for light bleaching (1 to 2 levels), 30 volume for medium bleaching (2 to 3 levels), 40 volume for maximum bleaching (3 to 4 levels).

79.Application: start with the darkest or most resistant areas (usually the nape and temples), then the lighter areas (the crown heats up faster).

80.Continuous monitoring: check the bleaching progression every 5 to 10 minutes.

81.Stopping point: as soon as the desired depth level is reached, rinse immediately.

Safety rule: never apply bleach to hair that has already been lightened or chemically treated without a prior strength test. The hair can degrade and break.

Safety Standards and Canadian Regulations

Canadian Electrical Code

Although the Canadian Electrical Code (CE Code) applies primarily to electrical installations, it is relevant for hair salons. Electrical outlets near water sources (shampoo bowls) must be protected by ground fault circuit interrupters (GFCIs) in accordance with Rule 8-200 of the CE Code. This rule requires protection of 125 V circuits supplying outlets located within 1.5 m of a water source.

Canadian Occupational Health and Safety Legislation

Hair salons are subject to the Occupational Health and Safety Act (OHSA) and related regulations. You must know:

WHMIS (Workplace Hazardous Materials Information System): every chemical product must have a Safety Data Sheet (SDS) accessible. Containers must be labelled in accordance with WHMIS.

Ventilation requirements: salons must have adequate ventilation to remove chemical vapours (ammonia, peroxide).

Personal protective equipment (PPE): gloves, safety glasses, aprons.

CSA Standards

CSA B149.1 (Natural Gas and Propane Installation Code) may apply if the salon uses gas appliances (water heaters, gas dryers). Installations must comply with this standard.

Hygiene and Sanitation

Disinfect tools (brushes, bowls, combs) between each client with an intermediate-level disinfectant (tuberculocidal).

Use single-use needles and razors.

Wash hands before and after each service.

Wear gloves when applying any chemical product.

Pitfalls to Avoid

Here are the most frequent errors on the Red Seal exam on this topic:

100.Confusing oxidant volumes: 10 volume ≠ 10% peroxide. 10 volume = 3% H₂O₂. The conversion is: percentage × 3.33 = volumes (approximately).

101.Forgetting the strand test: the examiner will systematically check that you perform the preliminary tests. Never skip this step.

102.Applying colour to the mid-lengths before the roots: for a touch-up, the roots must be treated first, unless the instructions indicate otherwise.

103.Neutralizing the wrong colours: memorize the colour wheel. Yellow is neutralized with violet, not blue (which would give green).

104.Ignoring hair porosity: porous hair absorbs colourant more quickly. Reduce processing time or use a weaker oxidant.

105.Calculating quantities incorrectly: for a full colouration on medium-length hair, plan for 60 to 90 g of mixture. For a root touch-up, 30 to 45 g is sufficient.

106.Using metal tools: metal can oxidize the mixture and alter the colour. Use plastic or glass bowls.

107.Confusing depth levels: level 1 is the darkest (black), level 10 is the lightest (platinum blonde). The scale is inverted compared to intuition.

108.Forgetting pH: the pH of hair is approximately 4.5 to 5.5 (slightly acidic). Permanent colourants have an alkaline pH (9 to 10) to lift the cuticles. After colouring, an acidic treatment closes the cuticles.

109.Neglecting safety: never apply colourant to an irritated or damaged scalp. Always wear gloves. Check product expiration dates.

Tips for the Practical Exam

Organize your workstation: all tools within reach, labelled products, clean towels.

Communicate your actions: explain each step to the examiner (strand test, oxidant choice, processing time).

Respect the times: use a timer. Never leave a product working unattended.

Document: note the formulation used (colour, oxidant, processing time) on the client's record card.

Verify the result: compare the final result with the requested depth level and tones.

Summary

Hair colouring is based on hair structure (cuticle, cortex, medulla) and melanin (eumelanin and pheomelanin).

Five categories of colourants: temporary, semi-permanent, demi-permanent, permanent, lightener.

Hydrogen peroxide is the standard oxidant. Volumes (5 to 40) determine the degree of lightening.

Mixing ratios: 1:1 for permanent colourations, 1:2 for bleaching (according to the manufacturer).

The colour wheel allows you to neutralize unwanted tones: yellow/violet, orange/blue, red/green.

Preliminary tests (sensitivity, strand, porosity) are mandatory.

Canadian standards: WHMIS, OHSA, CE Code Rule 8-200 (GFCI near water sources), CSA B149.1 for gas installations.

Main pitfalls: confusion of volumes, incorrect neutralizations, forgotten tests, calculation errors, failure to respect processing times.

Self-Assessment Questions

126.What is the difference between a semi-permanent and a permanent colourant?

127.What volume of oxidant would you use to lighten naturally dark brown hair (level 3) by 3 levels?

128.How do you neutralize an unwanted orange tone on lightened hair?

129.What is the H₂O₂ concentration of a 30 volume peroxide?

130.What are the three layers of the hair and which one is the site of melanin?

131.Why should you never use a metal bowl to mix a colourant?

132.Which rule of the Canadian Electrical Code protects outlets near water sources?

133.What is the normal pH of hair and why is it important in colouring?

This chapter covers the essential knowledge for the Red Seal exam in hairstyling, colouring and lightening section. Review regularly, practice the calculations, and memorize the reference tables. Good luck with your preparation.

Hair Colouring and Lightening