What the Number Order Means in an Igora Dye Code

Q: Does this order rule apply the same way across every dye brand?

Not necessarily. The first digit leads principle is what Schwarzkopf publishes for its Igora chart. Other brands run their own reflection system — check their documentation before applying the same logic to another line.

Are 7-42 and 7-24 the same shade with the digits shuffled, or two different tones? They carry the same level — a 7 — and the exact same two reflections: beige and ash. The only thing that changes is the order they’re written in. And that order decides which of the two tones leads.

If you formulate every day, you’ve probably grabbed one while meaning the other at some point. Same line, same two digits, and at a glance they look like the same code read backwards. They aren’t.

Let’s look at what the manufacturer actually says about that order, what really changes between the two codes, and on which type of base the difference shows up — because it isn’t where you’d expect.

Quick summary: in a hair dye code with two reflection digits after the dash, the first one marks the dominant tone direction and the second the secondary one — that’s how Schwarzkopf publishes it for its Igora chart. In 7-42, beige (4) leads and ash (2) supports. In 7-24, it’s reversed: ash leads and beige falls back. Same level, same two reflections, different result.

What does the number order after the dash actually mean?

The first digit after the dash is the dominant tone direction; the second is the secondary one. That’s exactly what Schwarzkopf Professional’s Igora Royal color chart states: “The first number after the dash represents the primary tone direction (the dominant shade). The second number after the dash indicates the secondary tone direction.”

This isn’t a manufacturer style quirk — it’s the instruction that decides which reflection actually runs the show once it’s in the bowl. Before the dash sits the level, 1 through 10, how light the base reads, and we already covered that in the hair color level guide. After the dash, when there are two digits, the first one isn’t just “the other reflection that’s also in there” — it’s the one steering the outcome. The second one shades it.

On Igora’s official reflection scale, digit 2 is ash and digit 4 is beige — the same scale we already used to explain the difference between ash and cendré in this line. With those two numbers plus the order rule, 7-24 and 7-42 stop looking like the same code written twice.

What exactly happens between 7-42 and 7-24?

They share the same level and the exact same two reflection digits, in reverse order, and that reversal flips which one leads. In 7-42, beige (4) dominates and ash (2) supports. In 7-24, ash (2) dominates and beige (4) supports.

Per the Igora Color System wall chart, reflection -2 is ash and reflection -4 is beige. With that key, each code’s own name confirms it digit by digit:

Code	Level	Dominant reflection	Secondary reflection
7-42	7	Beige (4)	Ash (2)
7-24	7	Ash (2)	Beige (4)

It’s the same pair of digits — 2 and 4 — read in two directions. And that’s not an interpretation: the shade names themselves, inside the brand’s own chart, are inverted the same way — one reads “beige ash,” the other “ash beige,” matching whichever digit comes first.

In other words, reaching for a 7-24 when the job calls for a 7-42 isn’t reaching for “close enough.” It’s asking for the same reflection with the hierarchy flipped — a result led by cool instead of warm, on the exact same level 7.

Two tubes with the Igora codes 7-42 and 7-24 on a salon counter, with the color chart open beside them to compare the tone

Where does the difference actually show up on hair?

On a virgin base, the gap between the two codes is fine — almost a nuance. It bites where it counts on porous or previously lightened mid-lengths: the dominant cool reflection grabs harder than expected there, and the result reads less warmed-down than the tube’s name suggested.

The physics behind it sits in the developer and the fiber itself: porosity doesn’t change which reflection dominates the formula — the digit order decides that, not the fiber — but it does change how hard that dominant reflection grips once applied. Porous hair pulls in more pigment and holds it tighter. If the dominant reflection is the cool one — 7-24, ash out front — that extra grip shows up as a result that reads flatter, more closed, than the target called for.

That’s why the mix-up rarely gets caught with the tube in hand. With the physical chart in front of you and a controlled processing time, the outcome is predictable. The slip happens somewhere else: a formula pulled from memory, a formula copied from someone else’s notes, or the assumption that “42 and 24 are interchangeable because they’re the same two numbers.” They aren’t, and on an already-processed base that assumption gets expensive.

Pro tip: if a formula comes in with a two-digit reflection code and you’re not sure which one leads, don’t assume from habit — check the order against your line’s physical chart. Whichever digit sits first after the dash is the one steering the result.

Hands of a color professional checking the Igora tone chart next to a porous strand of hair on a salon counter

Does this order rule hold across other brands too?

The principle — first digit leads — is specific to how Igora builds its own nomenclature; other brands run their own system, and that’s worth checking against their own chart before assuming it carries over. We covered this when talking about what happens when you mix two dyes: reflection digits are each manufacturer’s own alphabet, not a shared standard across brands. What this adds is one more layer inside that same alphabet — not just what each digit means, but what the order means when there are two of them.

Before assuming a formula from another line follows the same “first one wins” logic, look it up in that brand’s own documentation. One house’s convention doesn’t automatically transfer to another.

What’s worth writing down on the client card after this service?

The exact code used — not just “a medium beige blonde” — and which reflection ended up dominant on that particular base. The real decision isn’t picking “a 7 with beige and ash.” It’s picking which of the two leads, and that choice depends on the starting base in front of you. Logging only the level and skipping the digit order throws away half the information — whoever opens that card at the next visit, whether that’s you in six weeks or someone else on the team, needs the exact code that was used, not an approximate description.

This ties into something bigger than today’s code: this appointment sets up the next one. If the 7-24 grabbed cooler than expected on a porous base, that’s data worth carrying into the touch-up — not to repeat the same slip, but to decide with evidence whether to stay with that code or move to the 7-42 next time.

Common mistakes when reading a two-digit reflection code

Assuming two matching digits in a different order are interchangeable: 42 and 24 share figures, not results. The order decides which reflection leads.
Formulating from memory instead of checking the physical chart: the slip rarely happens with the tube in hand — it creeps in through a written order or a copied formula.
Not distinguishing level from reflection when reading the code: the number before the dash is the level; the digits after it are the reflection, and that’s where the dominant/secondary order lives.
Ignoring what porosity does to the dominant reflection: the order decides which reflection runs the formula; porosity decides how much that dominance shows on that particular fiber. Two separate questions in the same diagnosis.

Frequently asked questions

What’s the difference between 7-42 and 7-24?

They share the same level (7) and the same two reflection digits (2 and 4), in reverse order. In 7-42, beige dominates and ash supports. In 7-24, ash dominates and beige supports. The manufacturer states that the first digit after the dash marks the dominant direction.

How do I know which reflection leads in a hair dye code?

Check which digit comes first after the dash — per Igora’s nomenclature, that’s the one steering the result. The second digit shades it, but doesn’t lead. When in doubt, always verify against your line’s physical chart.

Does the difference between 7-42 and 7-24 actually show in practice?

It depends on the base. On virgin hair, the gap is fine, almost a nuance. On porous or previously lightened mid-lengths it shows more: the dominant cool reflection in 7-24 grips harder and the result reads flatter than expected.

Does this order rule apply the same way across every dye brand?

Not necessarily. The “first digit leads” principle is what Schwarzkopf publishes for its Igora chart. Other brands run their own reflection system — check their documentation before applying the same logic to another line.

In summary

The first digit after the dash marks the dominant tone direction; the second, the secondary one
7-42 (beige leads, ash supports) and 7-24 (ash leads, beige supports) share level and digits, not results
On virgin hair the difference is fine; on porous or previously lightened fiber the dominant cool reflection grips harder and the result reads flatter
The mix-up almost never happens with the tube in hand — it slips in through a formula pulled from memory or a copied note
The principle is specific to Igora’s nomenclature: on another brand, check its own chart before assuming it carries over

Formulate without memorizing every code’s digit order

Inside the Blendsor app, the AI works directly with your brand’s own tones and ratios, resolving which reflection dominates in each formula so you don’t have to memorize the digit order behind every code on the chart. Formulate with Blendsor.

And in your day-to-day, has a code mix-up ever caught you out?