Donna che applica il balsamo sulle lunghezze dei capelli bagnati con le mani

Conditioner, mask, or leave-in: differences and when to use them

of Elisa Avalle , founder of LeLang

4 min read

Conditioner, mask, spray, serum, oil: on store shelves they seem like five different categories, but in reality they belong to the same family. They are all conditioners, meaning products that deposit on the hair to make it smoother, shinier, and easier to comb. What changes is how long they remain on the hair, how concentrated they are, and which hair type they work best for.

Article written by Elisa Avalle, founder of LeLang Skin Care and dermocosmetics specialist. Cover image generated with the support of artificial intelligence.

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Why hair needs a conditioner

The outer layer of the hair, the cuticle, is made up of small overlapping scales like roof tiles. When they are compact, the hair reflects light, glides smoothly, and does not tangle. Heat, chlorine, vigorous brushing, dyes, and bleaching lift or break these scales: the hair becomes dull and rough, tangles, and breaks more easily.

A conditioner forms a thin film on the fiber that flattens the scales. It does not repair the hair in a biological sense, because the shaft is not living tissue, but it genuinely improves its appearance and resistance to friction.

Washed hair has negative electrical charges. Many conditioners have positive charges and therefore attach precisely where the hair is most damaged: this is why the ends benefit more than the roots.

What a conditioner contains

Cationic substances, such as behentrimonium chloride or stearamidopropyl dimethylamine: they neutralize static electricity and make combing easier.
Polymers, such as cationic guar and polyquaterniums: they add body, but can build up if used very frequently.
Silicones, such as dimethicone and amodimethicone: they make hair smooth and shiny. Amodimethicone withstands more washes.
Lipids: plant oils, esters, waxes, ceramides.
Low-molecular-weight humectants, such as panthenol and glycerin, and hydrolyzed proteins, which deposit mainly on damaged hair.
Weak acids, such as citric or lactic acid, which lower the pH and help close the cuticle.

With rinsing: conditioner and mask

The conditioner

It is a semi-fluid emulsion to use after shampooing, with every wash. Leave it on for one or two minutes and rinse. It is designed for normal or dry-prone hair and frequent use.

The mask

It has a thicker consistency and is more concentrated: more oils, more proteins, and often a longer-lasting silicone. It generally has an acidic pH, between 4 and 5.5, which closes the cuticles and increases shine. Apply to towel-dried lengths, leave on for 5 to 15 minutes, and rinse well. Once or twice a week, or every two weeks, depending on how damaged the hair is.

The difference between conditioner and mask is not one of nature, but of amount. Conditioner is maintenance with every wash; a mask is a periodic treatment.

Leave-in: leave-in products

Single-phase spray

A very fluid, water-based solution that is sprayed onto damp or dry hair. It is lightweight and not very greasy: suitable for fine hair, hair that becomes oily quickly, and children, provided the roots are avoided. It is usually not enough for thick, curly, or very dry hair.

Two-phase spray

It has two visible phases: a water-based one, with panthenol, glycerin, and proteins, and an oily one, with silicones and fat-soluble vitamins. Shake before use. It makes hair soft and very shiny without weighing it down: the choice for normal or dry-prone hair.

Serum

It is highly concentrated: three or four drops, from the lengths to the ends, are enough. It reduces frizz and static electricity and leaves hair silky. If too much is used, the hair looks dirty.

Cream and oil

Leave-in cream is suitable for thick, coarse, dry, or curly hair, and for protection from the sun and wind. Oil, made from plant oils and esters, is used on the ends or as a pre-shampoo treatment for severely damaged hair. For fine hair, dry oils are best; for thick hair, richer oils.

How to choose based on your hair

Fine or oily hair: lightweight conditioner only on the lengths, or single-phase spray. Avoid rich products at the roots.
Normal hair: conditioner with every wash, two-phase spray if detangling and shine are needed.
Dry, colored, or bleached hair: conditioner every time and a mask once or twice a week, plus a serum on the ends.
Curly or very thick hair: leave-in cream or oil, applied to damp hair.

The most common mistakes

Applying conditioner to the scalp: it weighs the hair down and, on an oily scalp, makes it get dirty sooner.
Using a mask at every wash on fine hair: over time, it weighs the hair down.
Rinsing too little: residue dulls the hair instead of making it shiny.
Thinking that conditioner can replace a haircut: split ends can be concealed, but they cannot be repaired.

Frequently asked questions

Can conditioner be used without shampoo?

Yes, this is the co-wash technique, used mainly on curly and very dry hair. It cleanses very little, so it is not suitable for an oily scalp.

Should conditioner also be applied to the roots?

Usually not. The scalp already produces its own sebum: conditioner is for the lengths and ends, which are the oldest and most damaged parts of the hair.

Are silicones bad for hair?

No. They make hair smooth and shiny. Water-insoluble ones can build up after many washes and weigh down fine hair: in that case, simply alternate them with products that do not contain them.