The developer is the half of a colour formula that people think about least and that decides most. It sets how much lift you get, how evenly you get it, and whether the formula still behaves by the time you reach the last foil. This guide covers the Must52 Peroxide Cream Developer — what the volume number actually means, why a cream base is not a cosmetic detail, and how to pick between the volumes on the shelf.
What the volume number measures
Volume is a direct expression of hydrogen peroxide concentration. 10 volume is 3%. 20 volume is 6%. 30 volume is 9%. 40 volume is 12%. Nothing else in the number is a claim — it is a percentage in old units.
What the concentration buys you is lift. Ten volume deposits: it opens the cuticle just enough to place colour, refreshes a faded mid-length, and drives a toner, with effectively no lift. Twenty volume is the everyday professional strength — it is what covers grey and lifts one to two levels, and it is the volume most permanent colour formulas are written around. Higher volumes lift further and are correspondingly harsher on the hair and the scalp.
Why pH control matters more than volume
A developer with an uncontrolled pH does not release its oxygen evenly. It fires hard at the start — usually right where you applied first, at the root, where scalp heat accelerates it further — and then stalls before the ends have caught up. The result is the defect every colourist recognises: hot roots and dragged, under-processed ends, on a formula that was mixed correctly.
The Must52 developer is pH-controlled specifically to keep the reaction steady from the first foil to the last. That is the single most useful thing to know about it: it is not sold on raw lifting power, it is sold on the oxidation staying predictable across a whole head.
Why cream and not liquid
A cream base carries the developer where you put it. A thin, runny developer runs — off the section, down the parting, onto the cape, and out of the foil. That is lost product, an uneven application, and a stained gown. Cream is also what lets a mixed formula sit on a fine section without soaking through and marking the section below it.
There is a second, quieter benefit: a cream mix is easier to see. You can tell at a glance which sections are covered and which are not, which is exactly what you cannot do with a clear liquid on damp hair.
Picking a volume
- Depositing colour, refreshing a mid-length, toning → 10 volume (3%)
- Grey coverage, one to two levels of lift, most permanent formulas → 20 volume (6%)
- Higher lift on resistant hair → higher volumes, mixed with a lightener rather than with colour, and only where the hair condition supports it
The Must52 litre is available in 10, 20 and 40 volume on a single product page — same price per litre, so stock the volumes your column actually runs rather than buying one and compromising.
Mixing and applying
- Mix in a non-metallic bowl, at the ratio your colour or lightener specifies. Metal reacts with peroxide; a plastic tint bowl does not.
- Always carry out a skin allergy test before a colour service, and wear gloves.
- Apply with a tint brush, working root to mid-length on a retouch and mid-length to ends first on a full head, so the scalp-heat area is not processing longest.
- Process for the time the colour requires — not the time the developer suggests. The colour manufacturer owns the timing.
Where lightener fits
Developer is one half of a lightening formula; the powder is the other. The Must52 Light Me Up blue lightening powder is the house lightener the litre is designed to mix with, and the practical rule is the same one that applies to every bleach: the volume you choose should be the lowest one that gets you to target in the time the hair will tolerate, not the highest one you can defend. A slower lift on 20 volume nearly always leaves better hair than a fast one on 40.
Frequently asked
Can I mix volumes to get an in-between strength?
Colourists do, and the arithmetic works — equal parts 10 and 30 gives you roughly 20. But you are mixing outside what the colour manufacturer tested, so the timing on the colour box no longer strictly applies. Buy the volume you need where you can.
How long does an opened litre last?
Peroxide degrades once it is exposed to air, light and heat. Keep the cap on, keep it out of direct sunlight, and keep it off a warm shelf near a dryer. A litre that has been sitting open on a colour bar for months will lift less than the label says, which is the usual explanation for a formula that "suddenly stopped working".
Do I need a different developer for toner?
No — a toner runs on 10 volume in almost every professional system, which is exactly what the 10 volume litre is for.
Why is my root lifting faster than my ends?
Scalp heat, almost always, compounded by a developer whose pH lets the reaction spike. Apply the root last on a full head, and use a pH-controlled developer so the two ends of the section are at least starting from the same place.