Is Heat Good or Bad for Hair? Rethinking Heat Through the Lens of Curly Hair Theory
For decades, the narrative around heat and hair has been overwhelmingly one-sided: “Heat is bad for hair.” Most people, especially those with curly or highly textured hair, have heard this warning from stylists, blogs, and product labels alike. But what if this statement is only partially true?
At Michal Harewood Inc., we operate within a different framework—Curly Hair Theory—which views the relationship between heat, hydration, porosity, and hair health through a more nuanced and scientific lens. This article outlines the major philosophical and practical divide between two contrasting schools of thought: Straightening Hair Theory and Curly Hair Theory, with the goal of educating stylists, clients, and researchers in the evolving field of textured hair care.
How does heat affect hair?
Two Theories. Two Realities.
1. Straightening Hair Theory: Heat as a Styling Tool
In the conventional beauty industry, hair is often treated as a blank canvas—something to be tamed, stretched, and reshaped to fit a desired aesthetic. This mindset is especially evident in the treatment of curlier hair types (3C to 4C), where heat is applied aggressively, often exceeding temperatures of 400°F to 500°F in an attempt to alter the hair’s natural structure.
Primary Goal: Break hydrogen bonds to flatten curl patterns
Tools: Flat irons, hot combs, blow dryers with brushes
Products: Silicones, petroleum, and plastic-based coatings
Result: A sleek, straightened style—often at the cost of moisture loss, cuticle erosion, and cortical damage
The truth is this kind of heat is damaging. It leads to:
Cuticle erosion and rupture
Elasticity breakdown
Melting of synthetic coatings on the hair shaft
Sealed-in toxins
Chronic dehydration and increased porosity
When stylists trained in this theory say, “Don’t use heat at home,” they’re absolutely right within their own framework. That level of heat is traumatic to the hair and has nothing to do with long-term health. It’s a short-term aesthetic procedure.
2. Curly Hair Theory: Heat as a Health Tool
In Curly Hair Theory, we recognize heat as a healing element when used with intention, knowledge, and hydration.
Curly hair evolved to thrive in hot, humid climates where:
Water was abundant (via environment or bathing)
There were no combs or styling tools
Hair naturally clumped, stretched, dried, and coiled through air and sun exposure
Our theory treats heat as part of a biological, not just cosmetic, function
We use heat for:
Hydration treatments
Protein fusions
Detoxification
Scalp circulation
Sanitizing (killing bacteria and balancing scalp pH)
Activating hydrogen bonds (setting curls and reducing porosity)
How Heat Works in Curly Hair Science
1. Heat + Water = Hydrogen Bonds
When water penetrates the cortex of curly hair and is then heated, it activates temporary hydrogen bonds that:
Set the curl into a defined shape
Lock in moisture
Prevent excessive porosity
Help styles last 3–10 days
In contrast, this bond-setting does not occur with air drying. Instead, air drying can:
Leave water in the hair shaft too long
Cause cuticles to lift
Encourage bacterial growth on scalp
Lead to itchy scalp, bad odor, or seborrheic dermatitis
2. Heat as a Detoxifier
When paired with clay masks or neem treatments, gentle heat is used to:
Increase blood circulation
Kill or inhibit bacteria bacterial growth
Support deeper detoxification
Stimulate lymphatic drainage
3. Heat in Color & Protein Treatments
Even the straightening world agrees: heat is essential for color, keratin, and protein fusion. Yet discussions around safe application for curls are rare. In Curly Hair Theory, we focus on:
Low, consistent heat
Conditioners rich in natural butters, herbs, and proteins
Closed-loop hydration cycles to prevent breakage
Why Air-Drying Often Fails Curly Hair
Contrary to popular belief, air-drying—though often seen as gentler—can actually compromise the health of textured hair. When clients air-dry their curls:
Water molecules don’t bond fully
The surface stays humid
Hair becomes frizzy, undefined, and more porous over time
The scalp can shift to an alkaline pH, inviting microbial imbalance
Sebum (natural oil) production is disrupted
Clients may put damp curls into ponytails, which creates:
Fungal growth (the source of that “wet dog” smell)
Inflammation and flaking
Breakage at tension points
Rewriting the Narrative: Heat is Not the Problem—Misdirected Heat Is
Instead of generalizing with phrases like “heat is bad”, we must say:
“High-heat straightening without hydration or purpose is harmful. But low or high, intentional heat used to seal in hydration, activate hydrogen bonds, and detoxify the scalp is essential for healthy curly hair.”
A Word on Evolution and Hair Structure
Human hair hasn’t fundamentally changed in 1.7 million years. Those with tighter curl patterns evolved in equatorial, humid climates and had no plastic coatings, petroleum oils, or harmful cosmetics interrupting their scalp function.
Modern curly clients live in colder, drier climates. If they want their curls to look defined and healthy—not just styled but thriving—we must recreate the conditions the hair originally adapted to:
Moisture + Heat
No plastic build-up
No sebum-blocking products
Consistent drying methods that protect porosity
Why Stylists and Researchers Must Pay Attention
Cosmetology textbooks published as recently as 2019 assert that curly hair must be straightened to be “maintained.” This claim reflects outdated assumptions and perpetuates misinformation.
There’s a critical distinction to make:
Heat for styling alters structure at a cost
Heat for health restores structure with intention
Curly hair care deserves its own theory, its own science, and its own professional standards—not adaptations of methods designed for straight hair.
Final Takeaway: Heat Isn’t The Problem. It’s How We Use It.
We must move beyond labeling heat as “good” or “bad,” and understand its contextual role.
In Straightening Hair Theory, heat is used to change the shape of the hair, often at its expense.
In Curly Hair Theory, heat is used to enhance structure, improve elasticity, balance the scalp, and preserve health.
Let’s move forward with an understanding that not all heat is equal, and that when aligned with hydration and biology, heat is one of the most powerful tools for hair and scalp wellness.
Robbins, C. R. (2012). Chemical and Physical Behavior of Human Hair (5th ed.). Springer.
Reed, J. T., & McMichael, A. J. (2001). Hair care practices in African-American women. Cutis, 68(5), 399-402.
Khumalo, N. P., & Jessop, S. (2005). Hair care and hairstyling practices in African children. Journal of the American Academy of Dermatology, 52(2), 194-200.
Kwack, M. H., Seo, C. H., & Sung, Y. K. (2014). Suppressive effects of triclosan on the growth of Malassezia restricta. Annals of Dermatology, 26(5), 564-569.