The Science of Hair Undertones: Identifying and Enhancing Cool, Warm, and Neutral Tones

Understanding hair undertones is one of the most critical skills for any stylist aiming to achieve flawless, personalized color results. The undertone of hair influences how a color will appear once applied and how it complements a client’s skin tone and overall look. Mastering the art of identifying and enhancing undertones allows stylists to create balanced, harmonious colors that enhance their clients’ features.

Here’s a guide for stylists on the science of hair undertones, how to identify them, and techniques to enhance or neutralize them for optimal results.

What Are Hair Undertones?

Hair undertones are the underlying pigments present in the hair that are revealed when hair is lightened or colored. These pigments fall into three main categories:

• Cool Undertones: Blue, green, or violet-based pigments that create ashy, silvery, or platinum effects.
• Warm Undertones: Yellow, orange, or red-based pigments that produce golden, caramel, or copper hues.
• Neutral Undertones: A balanced mix of warm and cool pigments, resulting in natural-looking shades that are neither too warm nor too cool.

Why Are Undertones Important?

Understanding and working with hair undertones is essential because:

• They Determine Final Results: Undertones influence how a color formula will appear once applied. For example, a golden blonde shade on hair with a strong yellow undertone may look overly warm if not adjusted.
• They Complement Skin Tone: Matching undertones to a client’s skin tone ensures the hair color enhances their natural beauty.
• They Prevent Unwanted Tones: Recognizing undertones allows stylists to counteract or neutralize colors like brassiness or greenish hues that can detract from the overall look.

How to Identify Hair Undertones

Before applying any color, it’s important to analyze the client’s natural hair color and any existing pigments. Here’s how:

1. Examine Natural Hair Color

   • Natural brunettes typically have warm red or orange undertones.
   • Natural blondes often have yellow undertones.
   • Black hair may contain cool blue or neutral brown undertones.

2. Observe Hair When Lightened

   • Lightening hair reveals the undertones more prominently. For example:
     • Level 5-6 (light brown to dark blonde): Orange undertones become visible.
     • Level 7-8 (medium blonde to light blonde): Yellow undertones dominate.
     • Level 9-10 (very light blonde to platinum): Pale yellow undertones emerge.

3. Use a Strand Test
   A strand test is an excellent way to confirm the underlying pigments before committing to a full-color service.

4. Consider Existing Color
   If the client has previously colored hair, assess the remaining pigments from prior treatments. These may alter how the new color interacts with the hair.

Enhancing and Neutralizing Undertones

Once you’ve identified the hair’s undertones, you can decide whether to enhance or neutralize them based on the client’s desired look.

• Cool Undertones

  • Enhancing: Use violet-based toners for ashy or silvery effects. For icy blondes, consider adding a hint of blue to counteract yellow warmth.
  • Neutralizing: To soften overly cool tones, incorporate a touch of gold or warm beige into your formula.

• Warm Undertones

  • Enhancing: Golden, copper, and caramel shades work beautifully to highlight warm undertones. Use yellow or orange-based dyes to emphasize warmth.
  • Neutralizing: Use blue or green-based toners to cancel out excessive brassiness or red hues.

• Neutral Undertones

  • Enhancing: Neutral undertones are versatile and work well with a variety of shades. For natural, dimensional results, use neutral-toned color formulas.
  • Neutralizing: Neutral undertones generally require less correction but can benefit from subtle cool or warm adjustments to suit the client’s skin tone.

Matching Undertones to Skin Tone

To create a cohesive look, match hair undertones to the client’s skin tone:

• Cool Skin Tones: Pair with cool undertones like ashy blonde, smoky brunette, or silvery hues. Avoid overly warm shades that can clash with the complexion.
• Warm Skin Tones: Opt for warm undertones like honey blonde, golden brown, or copper. Avoid excessively ashy shades that may appear flat.
• Neutral Skin Tones: Clients with neutral skin tones can pull off both warm and cool shades, making them the perfect candidates for versatile color palettes.

Tools and Techniques for Working with Undertones

Maximize your results with these professional tools and techniques:

1. Color Wheel Mastery
   Use the color wheel to neutralize unwanted tones effectively. For instance:

   • Use violet to cancel out yellow.
   • Use blue to neutralize orange.
   • Use green to reduce red.

2. Toning Is Key
   Toners are essential for refining undertones after lightening. Customize your toner formulas to enhance or neutralize based on the client’s goals.

3. Layering Techniques
   For dimensional color, layer highlights and lowlights to balance warm and cool tones. This adds depth and movement to the hair.

4. Customized Formulas
   Every client is unique. Create custom formulas that take into account the starting undertones, desired color, and maintenance preferences.

Troubleshooting Common Undertone Challenges

Even with careful planning, undertone challenges can arise. Here’s how to handle them:

• Excessive Brassiness: Use a blue or purple toner to neutralize warmth. If the brassiness persists, consider lifting the hair another level.
• Flat or Dull Color: Add a mix of cool and warm tones to create a balanced, multi-dimensional effect.
• Uneven Undertones: Correct uneven tones with spot toning or by applying different formulas to specific sections.