Curling: Creating temporary curls using heat or setting

What is Curling?

Curling is a hair styling technique that uses heat, tension, or chemical bonds to temporarily or permanently reshape straight hair into a curved or spiral form. It works by breaking and reforming the hair’s internal bonds to hold a new shape. Most people don’t realize that the heat from a curling iron can actually create tiny steam bubbles inside the hair shaft, which is a primary cause of long-term heat damage.

How Curling Reshapes Your Hair Bonds

Your hair’s shape is held by three types of bonds. Hydrogen bonds are weak and break with water or heat. Salt bonds are also weak and affected by pH changes.

Disulfide bonds are the strongest, found in the hair’s cortex. Think of them like the sturdy rungs on a rope ladder. Permanent curls from a perm break and reform these bonds. Heat styling only temporarily overcomes the weaker hydrogen bonds.

I see the most breakage when clients curl over previously heat-damaged sections. The hair’s inner structure is already compromised and can’t handle more stress.

Why Humidity Undoes Your Perfect Curls

Humidity attacks the hydrogen bonds that heat styling temporarily sets. Moisture in the air penetrates the hair shaft, causing those bonds to revert to their natural state.

This is why your curls fall flat on a humid day. Think of your hair like a piece of paper that you’ve rolled up; introducing moisture makes it want to unroll and lie flat again.

In my clinic, I always recommend a strong hold spray with humidity blockers for clients who live in moist climates. It creates a protective shield around each strand.

The Hidden Heat Damage from Daily Curling

Consistent heat styling causes cumulative damage that isn’t always visible immediately. Each time you apply heat above 300°F, you risk creating “bubble hair.”

This is where tiny steam bubbles form inside the hair shaft, weakening it from the inside out. The strand becomes brittle and prone to snapping off.

Over 80% of my clients who complain of breakage are daily heat tool users. They’re often surprised to learn the damage comes from the inside, not just the surface.

Will It Work For You?

Yes

• If your hair is in good condition with normal to low porosity.
• When you use a professional-grade thermal protectant on dry hair.
• If you have a consistent hair type from roots to ends.

No

• If your hair is already chemically processed or has high porosity.
• When you are experiencing active breakage or split ends.
• If your scalp is sensitive or you have inflammatory conditions like seborrheic dermatitis.

From My Experience

I advise my patients to treat heat styling like a special occasion tool, not a daily routine. The single biggest mistake is curling dirty hair loaded with dry shampoo and product buildup.

This combo acts like an oven on your strands, baking in the debris and accelerating damage. Always start with freshly cleansed, product-free hair for the safest thermal styling.

For long-lasting curls without the heat, consider a beach wave technique that uses no-heat methods for a gentler result.