Hair Smoothing Serum — Silicones, Oils and the Science Behind Anti-Frizz

Why does hair frizz? The science behind frizz

Before we discuss smoothing serum, it helps to understand why hair frizzes in the first place. Frizz isn't a matter of "bad hair" — it's pure physics and chemistry at the level of the hair's structure.

Human hair contains hydrogen bonds that link keratin chains within the hair's cortex. These bonds are temporary — they break under the influence of water (which is why wet hair changes shape) and reform once it dries. The trouble starts when air humidity is high: water molecules from the air penetrate the hair structure, break the hydrogen bonds and form new, irregular connections. The result? The hair changes shape in an unpredictable way — frizz.

The more damaged the cuticle (the hair's outer layer), the more easily water penetrates inside. That's why porous, colour-treated, heat-styled and chemically treated hair frizzes more than healthy hair. A smoothing serum works precisely at this level — it creates a barrier that limits moisture penetration.

Dimethicone — the most popular silicone in smoothing serums

Dimethicone (polydimethylsiloxane) is the flagship silicone in hair cosmetics. On the INCI list of most smoothing serums it ranks first or second. Its mechanism of action relies on forming a hydrophobic (water-repellent) layer on the hair's surface.

Dimethicone has exceptional physical properties: it's insoluble in water, has very low surface energy (which is why it spreads evenly across the hair), doesn't penetrate the hair's interior and forms a smooth, uniform film. This film "smooths" the raised scales of the cuticle, reflects light (hence the shine effect) and blocks moisture from the air (hence the anti-frizz effect).

There is, however, an important caveat: dimethicone is insoluble in water and requires surfactants (shampoo) to be removed. With frequent use and without proper cleansing it creates build-up — a layer that over time makes hair heavy, dull and "oddly slippery." You'll find a detailed dimethicone profile in our ingredient database.

Cyclomethicone and Amodimethicone — new-generation silicones

Not all silicones are the same. Cyclomethicone (cyclopentasiloxane) is a volatile silicone — it evaporates after being applied to the hair, leaving only a thin layer of other silicones (usually dimethiconol) that have "stuck" to the hair's surface. Thanks to this, it doesn't cause build-up as quickly as dimethicone.

Amodimethicone is an amine-modified silicone — it has amino groups that bind to damaged spots on the hair. This means it deposits selectively: more where the cuticle is damaged, less on healthy sections. It is the most advanced silicone used in serums and is considered acceptable by some CGM advocates because it doesn't create heavy build-up.

A hierarchy of silicones by build-up risk:

• Dimethicone — highest risk, insoluble in water
• Amodimethicone — moderate risk, selective binding
• Cyclomethicone — low risk, volatile (evaporates)
• Dimethicone Copolyol — lowest risk, water-soluble

Natural oils as an alternative — argan, jojoba, marula

Plant oils are a natural alternative to silicones in smoothing serums. They work on a similar principle — forming a protective layer on the hair's surface — but with significant differences in mechanism and effect.

Argan oil (Argania Spinosa Kernel Oil) is probably the most commonly used oil in hair serums. It contains fatty acids (oleic and linoleic), vitamin E and squalene. It penetrates the hair's interior better than silicones, which means it not only smooths the surface but also nourishes from within.

Jojoba oil (Simmondsia Chinensis Seed Oil) is technically not an oil but a liquid wax. Its structure is similar to human sebum, which makes it excellent at regulating hair's moisture without leaving it greasy.

Silicones vs oils comparison:

• Silicones — stronger anti-frizz effect, higher shine, build-up risk, don't nourish
• Oils — gentler smoothing effect, nourish, can weigh down fine hair, no build-up

CGM-friendly alternatives — flaxseed gel, aloe and natural polymers

The CGM method excludes water-insoluble silicones, which rules out most classic smoothing serums. The CGM community has, however, developed alternative anti-frizz solutions:

Flaxseed Gel — a homemade or commercial product made from flax seeds, rich in natural polysaccharides that form a light film on the hair. It works similarly to Carbomer in gels but is entirely natural. It defines curls and reduces frizz without weighing hair down.

Aloe Vera Gel — aloe gel contains polysaccharides (acemannan) that hydrate and form a delicate barrier on the hair. It's lighter than flaxseed gel and works better on fine and low-porosity hair.

Glycerin — a powerful humectant that, in the right climatic conditions (40–60% humidity), hydrates hair beautifully. In a very dry or very humid climate, however, it can make things worse — in dry air it "pulls" water out of the hair, and in humid air it draws excess water from the air, causing frizz.

If you're looking for silicone-free serums, use our product search to filter by INCI compositions.

How to use smoothing serum? Chemistry-based rules

Quantity matters. Silicone serum is highly concentrated — 1–2 drops on medium-length hair is usually a sufficient dose. Excess silicone doesn't give a better result; it only weighs the hair down and accelerates build-up.

Apply serum to damp hair, focusing on the lengths and ends. Avoid the roots — silicones near the scalp can create a greasy feel and hinder the growth of natural volume. Warm the product in your hands before applying — heat lowers the silicone's viscosity and makes it easier to spread evenly.

If you use silicone serum regularly, use a clarifying shampoo every 7–14 days to remove accumulated silicone. Check out cleansing products in our catalogue.

What to look for when choosing a serum?

Choose a serum suited to your hair and care method. Thick, porous and curly hair responds best to a serum with amodimethicone or argan oil. Fine hair needs light formulas with cyclomethicone or dimethicone copolyol. CGM followers should reach for flaxseed gel, aloe or a serum containing only water-soluble silicones.