The hair mask is one of many hair care products but its demand continues to rise, now occupying a central role in modern hair care routines to counter daily aggressors (heat styling tools, UV radiation, pollution, frequent washing or chemical treatments, etc.) that hair endures and which cause damage. Applying a hair treatment may seem straightforward, but there are several subtleties to consider, particularly concerning the timing of its application within a routine. This is what we will endeavour to address in this article.
Before or after shampooing: when is the ideal time to apply a hair mask?
Published on July 18, 2022, updated on December 26, 2025, by Stéphanie, PhD, Doctorate in Life and Health Sciences — 7 min of reading
Themes:
1
applications per week on average for a hair mask
10 to 30
Recommended contact time in minutes for a hair mask
4 minutes to understand your skin. Our dermatological diagnostic guides you toward the ideal skincare for your specific needs. Simple, quick, personalized.
What is the purpose of a hair mask?
Hair is continuously exposed to mechanical, chemical or thermal stress that may alter its structure and shine. However, being composed of dead cells, it cannot biologically regenerate. The only way to restore its properties is therefore to act physically on the fibre using specific treatments. It is in this context that hair masks serve their primary function.
Very similar to so-called instant conditioners, the hair masks are deep treatments with a thicker texture and a formula more concentrated in active ingredients. Presented in the form of an emulsion for optimal effect, they penetrate more deeply into the fibre and act over an extended period, this which will greatly influence the quality and appearance of the hair. Particularly suited to dry or damaged hair, these intensive treatments revitalise the hair fibre by leaving it on for longer compared to that of a classic conditioner, before being thoroughly rinsed with water.
How does a hair mask work?
Most hair masks are formulated with a blend of multiple families of active ingredients to optimise their efficacy : cationic conditioning agents, lipids/fatty alcohols, film-forming agents and hydrolysed proteins.
The surfactants cationic adhere to the damaged areas of the fibre, which are naturally negatively charged. Their positive charge creates an electrostatic interaction that forms a smoothing protective film, reduces static electricity and facilitates detangling while enhancing shine.
The lipids, fatty alcohols and film-forming agents restore the external lipid layer of the hair shaft. They lubricate the hair surface, reduce friction between the fibres and enhance light reflection, thereby improving shine and softness. They also help maintain hydration within the cortex.
The proteins hydrolysed penetrate the fibre and temporarily fill the micro-cracks in the cuticle, enhancing the hair’s mechanical strength and reducing breakage.
| Ingredients | Roles | Examples |
|---|---|---|
| Cationic compounds | Reduce static electricity and limit friction between hair fibres | Quaternary ammonium salts (cetrimonium chloride, behentrimonium chloride, stearalkonium chloride, etc.), long-chain amine esters, etc. |
| Film-forming polymers | Cover or fill the damaged surface of the cuticle | Synthetic polymers (silicones, polyvinylpyrrolidone, polyacrylates, etc.), natural polymers (vegetable oils, vegetable butters, vegetable waxes, cellulose, starch, etc.), gums, fatty alcohols (cetyl alcohol, stearyl alcohol), etc. |
| Proteins | Temporarily restore lost proteins and enhance hair strength. | Hydrolysed proteins (amino acids, small peptides) |
The principal components of a hair mask.
When is the optimal time to apply a hair mask?
Beyond its formulation and specific instructions for use, the efficacy of a hair mask also depends on the timing of its application.
Haircare routine: at which stage should you apply a hair mask?
It is more common to apply a mask after shampooing, onto damp but not waterlogged hair.
It is recommended for the majority of hair masks to always wash the hair before applying them, in order to remove residues that could undermine the product’s efficacy. They are also used after chemical treatments such as colouring and smoothing agents. However, certain hair masks—particularly those based on clay—are applied before shampooing, directly onto the scalp.
How frequently should one apply a hair mask?
There is no universal frequency : it depends on hair type, the extent of damage, and the kind of mask selected (rinse-out or leave-in). Therefore, it is essential to follow the instructions on the product label meticulously. That said, in most cases hair masks are used less frequently than a conditioner, which is applied during every wash cycle. As a general rule, they are applied once a week as a regular maintenance treatment.
Although these guidelines are general, your hair is unique and may therefore require more or less application. Therefore, application should be adapted accordingly. Too frequent application can weigh down the hair and make it greasy, which would be counterproductive, whereas too infrequent use may leave hair dry and brittle. In all cases, refer always to the product instructions to ensure optimal use and achieve the best results.
… Sources
FAAD, M.D., et al. Hair Cosmetics. Cosmetics and Cosmetic Surgery in Dermatology (1991).
Shapiro J. et al. Hair care products: perming, straightening, conditioning and colouring. Clinics in Dermatology (2001).
REIS M. F. & al. Hair cosmetics – An overview. International Journal of Trichology (2015).
Sanjay K. et al. Shampoos and conditioners – what every dermatologist needs to know? Indian Journal of Dermatology (2015).
AGUH C. et al. Breaking the cycle of hair breakage – key insights for the management of acquired trichorrhexis nodosa. Journal of Dermatological Treatment (2017).
Guzmán E. et al. Physicochemical aspects of the performance of hair-conditioning formulations. Cosmetics (2020).
RASTEIRO M. G. et al. On the physicochemistry of hair care: from structure and degradation to novel bio-based conditioning agents. Polymers (2023).
