The Science Behind Curly Hair

Curly hair has a reputation for being unpredictable. In reality, it is doing exactly what it is built to do. Once you understand the basic structure, a lot of the everyday frustrations make more sense, why it frizzes, why it shrinks, why it feels dry at the ends, and why one cut works brilliantly while another feels like hard work.

This is a simple guide to what makes hair curly, and how that knowledge helps you get better shape, definition, and manageability.

1. Curls start at the root, the follicle shape matters

One of the biggest influences on whether hair grows straight, wavy, curly, or coily is the shape of the hair follicle under the scalp.

A rounder follicle tends to produce straighter hair. A more oval or curved follicle encourages bends and spirals. That is why curl pattern is not something you can fully change with product alone. You can improve health and definition, but the foundation is structural.

What this means in the salon is that the cut has to work with how your hair naturally grows, not how someone wishes it would behave.

2. Most people have more than one curl pattern

It is very common to have different patterns across the head. Looser texture at the nape, tighter curls at the crown, and a different curl direction at the front.

This is one reason textured cutting is more technical than people think. The goal is not to force everything into one uniform look. The goal is a balanced shape, where each area has what it needs to sit well when dry.

3. The bonds inside the hair influence curl behaviour

Hair is made mostly of keratin, and within each strand there are bonds that contribute to strength, elasticity, and form.

Disulfide bonds are a big part of why hair holds its natural structure. Heat, harsh chemical processing, and rough handling can weaken the hair over time. When that happens, the curl pattern can look less defined, feel drier, and be more prone to breakage.

The takeaway is not to be scared of styling. It is to be intentional. Healthy curls respond better to everything, including cuts, colour, and styling.

4. Porosity explains why some curls drink moisture and others repel it

Porosity is how easily your hair absorbs water, and how easily it loses it again.

Higher porosity hair often absorbs moisture quickly but struggles to hold onto it. It can feel dry, frizz easily, and tangle more. Lower porosity hair can resist water and product at first, then feel coated or heavy if products build up.

This is why one person thrives on richer creams and another feels better with lighter hydration and a good cleanse. When product choices feel confusing, porosity is often the missing piece.

5. Humidity and frizz, especially in Manchester weather

Hair is hygroscopic, which simply means it takes in moisture from the air. On humid days, water enters the strand, the strand swells, and curl clumps can separate. That is the classic frizz halo.

The fix is rarely just “more product”. Better results usually come from:

• A routine that keeps moisture balanced, so hair is not desperate for water from the air
• Styling hold that keeps curl clumps together
• Drying methods that suit your texture, often hands off once styled

If your hair changes dramatically outdoors, that is not you doing it wrong. It is your hair responding to the environment.

6. Why textured hair can feel drier at the ends

With curls and coils, natural scalp oils have more bends and turns to travel down the strand, so ends are more likely to feel dry.

That is why ends and perimeter shape matter so much. A well planned cut protects the hair visually and physically, and helps curls sit better for longer without constant re styling.

7. What the science means for the right cut and shape

Curly hair is three dimensional. It springs up, drops down, expands out, and changes with drying.

So the cut needs to account for:

• Shrinkage, so the dry length and shape are predictable
• Density, so the hair does not balloon where you do not want it
• Curl clumping, so curls look defined rather than separated and fluffy
• Your real life routine, because the best cut is the one you can wear easily

This is where specialist experience shows. Good shaping is not about taking more hair off. It is about taking the right hair off, in the right places, with the end result in mind.

8. Small changes that make a big difference at home

If you want the practical version, start here:

• Cleanse properly, build up is a major cause of dull, undefined curls
• Condition with slip, so curls form clumps and detangle gently
• Style on damp hair, then stop touching it while it dries
• Use a drying method that suits your hair, air dry or diffuse, but be consistent
• Protect at night, less friction means better second day hair

If you are stuck, bring your current products and routine to your appointment. A few small tweaks usually beat a full routine overhaul.

FAQs

Can your curl pattern change over time
Yes. Hormones, heat damage, chemical processing, and breakage can all change how curls appear and how they behave.

Why do my curls look good one day and not the next
Usually a mix of humidity, moisture balance, build up, and how the hair was dried and handled.

Do I need loads of products to have good curls
No. Most people do better with fewer products used well, plus a cut that creates the right shape in the first place.