Developer 101 – What Every Hairstylist Should Understand About This Magic in a Bottle

If hair color is the paint, then developer is the brush that activates the magic.

Understanding developer isn’t just about knowing which number to grab off the shelf—it’s about knowing why you’re using it, how it works, and what results to expect. Whether you’re a cosmetology student, a new stylist, or brushing up on your fundamentals, mastering developer can take your color game from basic to brilliant.

Let’s break it down.

🔬 What

Is

Developer?

Developer is a creamy liquid that contains hydrogen peroxide. Its job? To open the hair cuticle and activate the color or lightener so it can penetrate the hair shaft.

Without it, color can’t process. It’s the essential partner to both permanent hair color and lighteners.

🧪 The Different Volumes & What They Mean

Developer is measured in volumes—typically 10, 20, 30, and 40 vol—and each one determines how much lift (lightening) or deposit (darkening) happens.

✨ 10 Volume – Deposit Only

• No lift.

• Best for toning or darkening hair.

• Great for refreshing ends or glossing.

✨ 20 Volume – Standard Lift

• Lifts 1–2 levels.

• Ideal for gray coverage.

• Most commonly used with permanent color.

✨ 30 Volume – Stronger Lift

• Lifts 2–3 levels.

• Great for lifting darker bases or high-lift shades.

• Be cautious—more lift = more stress on the hair.

✨ 40 Volume – Maximum Lift

• Lifts 3–4 levels.

• Used for high-lift blondes or strong lighteners.

• Can be harsh—watch the timing and strand integrity.

💡 Pro Tip: Higher volume doesn’t mean better results. It means more lift, but also more potential damage. Always pair volume with hair condition and desired outcome.

🎨 Developer + Color = A Perfect Pair

The developer you choose directly affects the outcome of your color formula. Using the wrong volume can lead to underdeveloped color, banding, or worse—fried hair.

Here’s a quick cheat sheet:

🛑 Things to Watch For

• Overprocessing – Leaving high-volume developer on too long can cause severe damage.

• Inconsistent Mixing – Always use the correct ratio (usually 1:1 or 1:2, depending on your brand).

• Skipping the Strand Test – Always test, especially on compromised or colored hair.

💡 Why This Knowledge Sets You Apart

Stylists who understand the “why” behind their formulas build more trust, deliver better results, and correct color issues with confidence. Knowing your developers gives you power—not just in the salon, but in your reputation.

When your client asks, “What’s that white stuff you’re mixing in?”—you’ll be able to answer with authority.

Final Thoughts

Developer might seem like the sidekick in your color formulas, but in reality, it’s the driver behind the scenes. Respect it, understand it, and choose it wisely.

Because being a great stylist isn’t just about knowing how to apply color—it’s about knowing how that color works.

-K❤️