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The Science Behind Peroxide: How to Achieve Better Colour Results

Peroxide mixing bowl

Why Understanding Peroxide Makes You a Better Colourist

As a freelance hairdresser, you don’t always have a salon team to bounce questions off so understanding the science behind your products is essential. One of the most important tools in your kit is peroxide (a.k.a. developer), yet it’s often the least understood. In this post, we’ll break down exactly how hair peroxide works, what it does inside the hair, and how to use it to get consistently beautiful results. Whether you’re lightening, covering greys, or toning blondes, a bit of science goes a long way.

“Knowing how peroxide works helps me avoid over-processing or under-lifting. It’s one of the best ways to build trust with my clients.”
– Nicola Wilcox, Freelance Hairdresser and Social Media Executive at Capital Hair & Beauty

What Is Peroxide in Hair Colouring?

Hair peroxide is an oxidising agent, most commonly hydrogen peroxide (H₂O₂), used to open the hair cuticle and allow colour to develop inside the hair shaft. It’s the chemical that activates both permanent colour and bleach, making it essential to every lightening and colour-lifting service.

Key functions of peroxide:

  • Lifts the natural pigment (melanin) in the hair
  • Activates ammonia or persulfates in tint and bleach
  • Deposits artificial pigment (in the case of tint)
  • Neutralises remaining pigment during toning

How Peroxide Works in Hair Colouring

  1. Alkaline pH (usually from ammonia or MEA) opens the hair cuticle.
  2. Peroxide breaks down melanin in the cortex lightening the hair's natural colour.
  3. Artificial pigment molecules are deposited (if using tint).
  4. Peroxide lifts the hair cuticle allowing the colour molecules to penetrate the hair.

Without peroxide you will not achieve the desired colour results.

Different Volumes, Different Results

Each peroxide strength affects how much pigment is lifted and how quickly it processes.

Volume %

H₂O₂

Result

6 vol

10 vol

1.9%

3%

Deposits tone only (no lift) ideal for toning or glossing

Lifts 1 level

20 vol

6%

Lifts 1–2 levels and covers grey

30 vol

9%

Lifts 2–3 levels often used with high-lift tint

40 vol

12%

Lifts up to 4 levels use with bleach or for strong lift

 

Common Colour Issues — Caused by Peroxide Misuse

Problem

Likely Cause

Patchy colour or banding

Uneven application or incorrect peroxide volume

Brassy results

Under-lifting with low volume or not leaving it long enough

Poor grey coverage

Using less than 20 vol, or too short a processing time

Breakage or porosity

Over-processing with high-volume peroxide or overlapping bleach

 

Capital Peroxide: Why It’s Trusted by the Trade

Capital Peroxide has been used by pro colourists for decades, and there’s good reason for that:

  • Balanced formula Smooth consistency and predictable lift
  • Trusted strength No “watered-down” results like some generic brands
  • Works with major colour brands
  • Ideal for freelancers –Affordable, accessible, and stocked in-store

Freelancer Tips: Getting the Most from Your Developer

  1. Know your ratios – Most tints mix at 1:1 or 1:1.5, bleach often at 1:2. Always check your colour brand’s instructions.
  2. Don’t leave out the timing – Developers need time to fully oxidise. Rinsing too soon = under-processing.
  3. Work in sections – Especially for root applications. Time = lift, so be consistent.
  4. Don’t “boost” lift with more peroxide – Going from 30 vol to 40 vol doesn’t speed things up, it just increases damage.
  5. Protect condition – Use bond-builders with bleach or high-vol developers to reduce stress on the hair.

Why Freelancers Love Capital Peroxide

You’re often balancing multiple clients, travel, and supply runs. Capital Peroxide makes life easier:

  • Grab it same-day from your local Capital store
  • Stocked in a range of sizes for convenience
  • Works across brands, so no need to carry multiple developers
  • Delivers clean lift, great tone, and professional results every time

“It’s consistent, affordable, and always on hand. That’s exactly what I need when I’m running mobile appointments.”
– Nicola Wilcox

FAQs: Peroxide Science Simplified

Q: Why do I need peroxide for hair colour?

It activates the colour and helps deposit it inside the hair. Without it, permanent colour won’t work.

Q: What happens if I use the wrong strength?

Too weak = not enough lift. Too strong = damage or unexpected tone. Use the right strength for the job.

Q: Does peroxide lighten hair on its own?

It can lift slightly, but without tint or bleach, the result is uneven. Always pair with the right product.

Elevate Your Colour Results With Knowledge

Understanding peroxide puts you in control of your colour results. Whether you're refreshing a root tint or taking a client platinum blonde, knowing the science means fewer surprises and better outcomes.

Capital Peroxide gives you reliable, salon-quality results every time without the fuss. It’s the unsung hero that makes your colour work shine.

Ready to colour with confidence? Shop Capital Peroxide here.

Pair it with pro favourites in our hair colour range.