Your developer does as much work as your colour. Pick the wrong strength and you can flatten a vibrant shade, leave stubborn grey behind, or burn the hair you were trying to beautify. Pick the right one and colour lifts cleanly, deposits evenly and the tone you mixed in the bowl is the tone you see in the mirror.
This guide walks through what hair developer actually does, how to read the volumes, and how to match your developer to the colour, the lift and the brand sitting in front of you. Bookmark it — it will save you more than one touch-up.
What is hair developer?
Hair developer — also called peroxide, oxidant or activator — is hydrogen peroxide in a stabilised cream or emulsion. On its own it does almost nothing you can see. Mixed with a permanent, demi-permanent or bleaching product, it does two jobs at once:
- Opens the cuticle so pigment (or lightener) can get inside the hair shaft.
- Activates the oxidative reaction — breaking down natural melanin for lift and developing the dye molecules for new tone.
Without developer, a permanent colour is just cream. With the right developer, it becomes a predictable, repeatable result.
Developer volumes explained (10, 20, 30, 40)
You'll see developers sold in volumes or percentages. They mean the same thing, just expressed differently. Here is what each strength is actually for:
10 Vol (3%) — deposit only
Almost no lift. Use this to deposit tone on pre-lightened hair, refresh mid-lengths and ends, and work with demi-permanents and glosses. If you want to tone a pale blonde or add richness to a faded colour without any lightening, 10 Vol is where you start.
20 Vol (6%) — one to two levels of lift
The industry workhorse. 20 Vol covers 100% white hair with a permanent colour, lifts one to two levels on natural hair, and is the default mixing ratio for most brand guides. If you're not sure, 20 Vol is nearly always the safer answer.
30 Vol (9%) — three levels of lift
For serious lifting on natural, un-coloured hair — for example going from a medium brown to a light brown or dark blonde in one session. It is stronger, warmer and more damaging than 20 Vol, so keep an eye on porosity and skin reactions.
40 Vol (12%) — maximum lift
Reserved for bleaching and specific high-lift blonde colours on strong, virgin hair. 40 Vol has no business near fine, porous or previously coloured hair on a regular mix, and it should never go on the scalp with most high-lift formulations — always follow the manufacturer's instructions.
Match developer to the job, not the habit
A common mistake is using the same developer for everything. Match it to what you actually want to achieve:
- Glossing, toning, refreshing colour: 10 Vol.
- Covering greys, going darker, or standard permanent colour with 1–2 levels of lift: 20 Vol.
- Lifting natural hair 3 levels with a permanent colour: 30 Vol.
- Bleaching (with powder lightener) or high-lift blondes: 30 or 40 Vol depending on the target level and the product's instructions.
- Demi-permanent colour (no ammonia): low-volume cream activator from the same brand, usually supplied at around 2–3% — never swap in a permanent developer.
Cream or liquid developer?
Most professional developers on the UK market are cream or emulsion-based, and for good reason. Cream developer blends into the colour smoothly, sits on the hair rather than running off, and gives a more even application — especially when you are working section by section. Liquid developers exist for specific product systems, but for everyday salon work with permanent and demi-permanent colour, a quality cream peroxide is the professional default.
The brand-specific picture
Every colour brand is formulated around its own oxidant. You can get a reasonable result swapping within the same family (for example, using a generic 6% cream peroxide with a permanent colour), but for predictable, on-shade results — especially for tonal work — stick with the developer your colour brand was tested against.
L'Oréal Professionnel
Majirel, Majirouge, Inoa and Majimix all sit on the oxidative side and mix with L'Oréal Professionnel Crème Oxydant, available in 10, 20, 30 and 40 Vol. For Dia Light and Dia Richesse — the demi-permanent gloss and tone ranges — you mix with the low-developer L'Oréal Dia Activateur instead. Never substitute one for the other. For a deep dive on the full L'Oréal system, see our L'Oréal Professional hair colour complete range guide.
Wella Professionals
Koleston Perfect mixes with Welloxon Perfect in the standard 1:1 ratio (or 1:2 with Special Blonde shades). Color Touch, Wella's demi-permanent, uses its own dedicated low-strength emulsion. Running into a tone question? Our guide on how to choose the right Wella Color Touch developer walks through every ratio. For the full shade picture, the Wella Professional hair colour complete range guide is the hub.
Schwarzkopf Professional
Igora Royal mixes with Schwarzkopf's own developer at 1:1, while the BlondMe lightening and toning system runs on its dedicated BlondMe Premium Developer. Igora Vibrance, the demi-permanent, uses its own activator lotion. Each step in the BlondMe system has a recommended developer strength — follow the chart on the box, not your instinct.
Truzone and value options
Not every job calls for a £15 litre. For bleaching, straightforward grey coverage and training work, Truzone Cream Peroxide is a consistent, affordable cream developer available in 10, 20, 30 and 40 Vol. It pairs well with generic permanent colours and most lighteners.
Mixing ratios you'll actually use
Ratios vary by product — always check the tube — but the everyday ones are:
- Permanent cream colour: 1 part colour to 1 part developer (1:1). Wella Koleston Special Blonde shades: 1:2.
- High-lift blondes (most brands): 1:2 with 30 or 40 Vol.
- Demi-permanent colour: usually 1:1.5 or 1:2 with the brand's activator.
- Powder lightener: 1:2 with 20, 30 or 40 Vol, adjusted for the target level and hair condition.
Pro tips and common mistakes
- Measure, don't eyeball. A kitchen scale or marked mixing bottle is worth its weight in perfectly-even colour.
- Stronger developer is not faster colour. Going from 20 Vol to 40 Vol will not double your lift, but it will multiply your damage.
- Porous hair eats developer volume. Previously coloured or bleached mid-lengths and ends need lower developer than the virgin regrowth at the root.
- Fresh is best. Developer starts oxidising the moment it's mixed — mix what you'll use in the next 30–40 minutes, and discard leftovers.
- Warm tones come from heat and volume. If you keep getting unwanted warmth, check whether your developer is too strong before blaming the colour.
Safety, patch tests and storage
Hydrogen peroxide is a professional chemical. Always carry out an Elasticity, Incompatibility and Allergy Alert / patch test 48 hours before a colour service, work in a ventilated space, wear gloves, and store developer upright in a cool, dark cupboard with the cap sealed. Heat and sunlight break peroxide down; a degraded developer won't lift properly and can give patchy results even if the colour is brand new.
Building your developer shelf
For most working colourists, a sensible starter shelf looks like this:
- A litre of cream 20 Vol for everyday permanent work.
- A litre of cream 30 Vol for extra lift and bleaching.
- A bottle of 10 Vol for glossing, toning and deposit-only services.
- A 40 Vol on standby for high-lift blondes and specific lightening jobs.
- Brand-matched activators for any demi-permanent range you offer — these are not optional add-ons, they are part of the colour system.
Ready to restock? Browse our full Hair Colour Products collection for every major professional range, or jump straight to the developer that fits your brand — L'Oréal Crème Oxydant, Schwarzkopf BlondMe Developer, L'Oréal Dia Activateur or Truzone Cream Peroxide. If you're unsure which strength suits your colour or your client's hair, our team are on hand — drop us a line via our contact page or browse the rest of the Hair Colour Tips blog for more brand-specific guides.