The pH Factor: Acidic vs Alkaline. When and Why?
Hey friends, Trent Matthews here, If we haven't met yet, I’m a Redken Artist and Educator who spends my time bouncing between the creative energy of NYC, and the sun-drenched vibes of Los Angeles. Whether I’m behind the chair or standing at the front of a classroom, my mission is the same: taking the "scary" out of hair chemistry and making it accessible for both my fellow stylists and my amazing clients.
In the world of professional hair color, we talk a lot about "shades" and "tones," but the real magic—the stuff that keeps hair shiny, healthy, and predictable—happens on the pH scale. Today, we’re diving deep into the science of the three main pillars of color: Acidic Demi-Permanent, Alkaline Demi-Permanent, and Permanent Color. If you’ve ever wondered what is in that tube of color I’m here to help give some insight to the chemistry behind the artistry of hair.
Understanding the pH Scale in Hair Care
Before we break down the products, let's talk about the canvas. Your hair is naturally at its happiest when it’s slightly acidic, sitting at a pH of 4.5 to 5.5. In this state, the cuticle (the outer layer of the hair) is closed tight, locking in moisture and reflecting light.
As a Redken Educator, I always teach that every time we apply color, we are essentially moving that pH needle. Where that needle lands determines how much "lift" we get and how the hair feels when you walk out of the salon.
s1. Acidic Demi-Permanent: The Ultimate "Closing" Tool
Let's start with my absolute favorite tool in the arsenal: Acidic Demi-Permanent color (think the iconic Redken Shades EQ).
The Chemistry: Acidic colors have a low pH, often sitting very close to the hair’s natural state. Instead of forcing the hair cuticle to swell and open, these formulas work to lower the pH of the hair. This action physically "seals" the cuticle back down.
Why Stylists Love It:
Zero Lift: Because it’s acidic, it cannot—and I mean cannot—lighten the hair. It only deposits tone.
Maximum Shine: By smoothing the cuticle, you get that glass-like reflection that every client craves.
Color Correction: It’s the perfect "safety net" for toning highlights or refreshing faded ends without shifting the natural base.
What Clients Need to Know: Think of an acidic gloss as the "top coat" or the "skincare" for your hair. It’s not meant to change your life—it’s meant to enhance your beauty while leaving the hair in better condition than it was before the service.
2. Alkaline Demi-Permanent: The Versatile Middle Ground
Sometimes, an acidic gloss isn't enough. Maybe we need a little more "oomph" for gray blending or a richer deposit. That’s where Alkaline Demi-Permanent color comes in.
The Chemistry: Unlike its acidic cousin, alkaline demi-permanent color has a pH of 8 to 9. This alkalinity causes the hair to swell slightly, allowing the color molecules to sit a bit deeper in the hair strand.
The "Warmth" Factor: This is where the "Hair Nerd" side of me comes out. When we raise the pH to 8 or 9, we are starting to disturb the natural pigment. While it’s still considered "demi Permanent," that alkaline environment can sometimes "expose" the natural warmth (the underlying orange or red tones) in your hair.
Pro Tip for Stylists: Understanding that an alkaline demi will shift the pH more than an acidic one is key to your formulation. If you have a client who is sensitive to "warmth," you might want to stick to an acidic formula so to avoid the long term battle of warmth it can create overtime.
3. Permanent Color: The Powerhouse
When we need 100% gray coverage or significant lightening, we reach for Permanent Color (like Redken Color Gels Lacquers or ColorFusion).
The Chemistry: Permanent color is the most alkaline of the bunch, typically sitting at a pH of 10 or above.
The Action: This high alkalinity blows the cuticle wide open, allowing the color to penetrate deep into the cortex (the heart of the hair).
The Lift: The higher the alkalinity, the more "lift" or lightening we achieve.
The Exposure: Because we are lifting so much, we are exposing the most amount of natural warmth. This is why permanent color requires the most precision in toning—to neutralize those raw, warm undertones that are revealed during the process.
The Redken Color Mantra: Zones 1, 2, and 3
In my Redken education classes, I teach a specific philosophy called the Color Mantra. This is how we use the science of pH to protect the hair’s integrity:
Zone 1 (The Roots): This is usually virgin hair. We use Alkaline or Permanent color here because we need that lift or gray coverage.
Zone 2 & 3 (Mid-shaft to Ends): This hair has usually been colored before and is more "porous" (open). We almost always use Acidic Demi-Permanent (Shades EQ) here.
Why? Because applying high-alkaline permanent color to hair that has already been "opened" before is a recipe for damage. By using an acidic formula on the ends, we refresh the color while simultaneously "sealing" the hair back down to a healthy pH.
Why This Matters for Your Next Appointment
Whether you’re a stylist looking to level up your color chemistry or a client who wants to know why their hair feels so different after a gloss, it all comes back to that pH scale.
As a Redken Artist, I believe that when we understand the "why" behind the bottle, we can create results that aren't just beautiful for one day—but stay healthy and vibrant until I see you again.
Ready to see the difference that pH-balanced color can make?
For Clients: Book your custom color session here at my Williamsburg or LA studios.
For Stylists: Check out my upcoming Redken Education schedule to dive deeper into formulation and the science of the "Hair Nerd" life!
Stay shiny, stay healthy, and I'll see you in the chair!
Trent Matthews