Hydrolysed Keratin: Why Stressed Hair Needs Protein

Short answer: Hair is mostly keratin, a protein, and bleach, colour, heat and friction wear its surface down. Hydrolysed keratin is keratin cut into fragments small enough to cling to those rough, porous spots, so damaged hair feels stronger, smoother and less fragile when wet. The effect washes out gradually, so it works as regular care.

Question	Short answer
What is it?	Keratin protein broken into small pieces so it can cling to the hair surface
What does it do?	Helps hair feel stronger and reduces the appearance of breakage and split ends
Who needs it?	Bleached, coloured, heat-styled or long hair that snaps or feels stretchy when wet
Who may not?	Uncoloured, coarse hair that already feels stiff; extra protein can make it feel straw-like
How often?	Once or twice a week is a normal starting point, not every wash

What is hydrolysed keratin?

It is keratin protein that has been deliberately broken into smaller pieces.

Whole keratin is a large molecule. Applied to hair, it sits on the surface and rinses straight off. Hydrolysis breaks it into shorter protein chains, and those fragments are small enough to attach to the rough, raised and porous parts of the hair surface. That is why hair cared for with protein feels smoother and less stretchy when wet.

The deposit is cosmetic. It washes out over the following shampoos, which is why protein care is something you repeat rather than something you do once.

Why does damaged hair need protein?

Because the wear that damage causes is mostly to the protein structure of the fibre, and moisture alone cannot stand in for it.

An undamaged hair has a smooth outer layer, the cuticle, laid like overlapping tiles around a protein-rich core. Bleach and permanent colour lift those tiles to do their work. Heat styling roughens them with less chemistry. Every brush stroke, towel rub and tight hair tie adds mechanical wear on top. The result is a porous fibre, full of small gaps.

Porous hair takes up water quickly and swells. That is the state people describe as "fine when dry, mushy and stretchy when wet, and then it snaps." A regular conditioner adds slip and softness, which helps with combing, but it does not add protein. Hydrolysed keratin does, temporarily, so the fibre behaves more like an undamaged one for a while.

Does my hair need protein or moisture?

Test a strand while it is wet; the way it stretches tells you more than the way it looks in a mirror.

Take one shed strand, wet it, and pull gently from both ends.

What the wet strand does	What it suggests	What to reach for
Stretches a long way, then snaps without springing back	Protein-depleted	A protein mask, weekly
Snaps almost at once with very little stretch	Too much protein, or very dry	Pause protein for a few weeks; condition and use an oil
Stretches a little and returns	Balanced	Keep your current routine

Most bleached and heat-styled hair lands in the first row. Uncoloured, coarse hair often lands in the second, which is why "protein overload" is a real complaint and not an internet myth. The test is a rough guide rather than a diagnosis, but it is far more useful than guessing.

How do you use a keratin hair mask?

On freshly shampooed, towel-dried hair, through the lengths and ends, for the time the label states.

1. Shampoo, then squeeze out the water. Hair that is already full of water takes up less of anything else.
2. Apply generously to mid-lengths and ends. That is where the wear is. The scalp does not need protein.
3. Leave it on. Our mask asks for five to ten minutes. A protein mask rinsed after thirty seconds has not had time to do much.
4. Rinse thoroughly. Use it in place of your regular conditioner that day.

Our Keratin Intensive Rescue Hair Mask follows this pattern. It combines hydrolysed keratin with wheat proteins and peptides, plus shea butter and vitamin E to condition dry lengths and ends, so hair feels softer and looks shinier. Two things to know before buying. It is the one product in our range that is not vegan, because hydrolysed keratin is animal-derived. And it contains wheat protein, so if you avoid wheat-derived ingredients, read the full ingredient list first. You can find it in our hair care collection.

How often should you use a protein mask?

Once or twice a week to begin with, then adjust based on how the hair feels.

After four weeks, repeat the wet-strand test. If the hair now snaps quickly with no give, or feels rough and stiff when dry, you have gone too far: drop to once every two weeks and use a plain conditioner in between. If it still stretches a long way and snaps, stay at once or twice a week.

Protein is not something you use more of because you like the results. You use enough of it, and then you stop adding.

What hydrolysed keratin won't do

It improves how the existing fibre looks and feels, and stops there.

• It will not seal a split end for good. A split is a physical tear. A mask can smooth it down so the end looks neater for a few washes. Only a trim removes it.
• It does nothing at the root or scalp. Everything here happens on the lengths that already exist.
• It is not a salon keratin smoothing service. Those use heat and different chemistry to change how hair behaves for months. A mask is a rinse-off product whose effect lasts a few washes.
• It will not outrun the cause. If you bleach every six weeks and flat-iron daily, the mask is a bucket under a leaking roof. Useful, but still a bucket.
• It will not make each hair thicker. Hair can look fuller when fewer lengths snap off, which is a smaller, honest promise.

Common mistakes

Most of them come down to using protein in the wrong amount or in the wrong place.

• Using protein on hair that already feels stiff. Rough, straw-like hair after a "strengthening" routine usually has too much protein, not too little.
• Applying to dripping-wet hair. Squeeze first. You will use less product and get more from it.
• Putting it on the scalp. Keep a protein mask to the lengths and ends.
• Rinsing too early. Give it the stated time.
• Judging it on one wash. One use feels pleasant. The real test is how your ends look, and how much broken hair is in your brush, after six weeks.

Frequently asked questions

What does hydrolysed keratin do for hair?

It deposits small protein fragments on the rough, porous parts of the hair surface. Hair feels stronger and smoother, and is less stretchy when wet, which reduces the appearance of breakage. The effect washes out over several shampoos, so it is used regularly rather than once.

How often should I use a keratin hair mask?

Once or twice a week is a sensible start for bleached, coloured or heat-styled hair. After a month, do the wet-strand test again. If the strand now snaps with almost no stretch, cut back to once every two weeks.

Can keratin fix split ends?

No. A split end is a tear, and only cutting removes it. A keratin mask can smooth splits so the ends look and feel neater for a few washes, and by making lengths less prone to snapping, it helps reduce the appearance of new breakage.

What is protein overload?

It describes hair that has taken on more protein than it needs and feels dry, rough and brittle rather than soft. The usual sign is a wet strand that snaps immediately with very little stretch. Pause protein products for a few weeks and use conditioner and a hair oil instead.

Is a keratin mask vegan?

Ours is not, because hydrolysed keratin comes from animal sources. It is the only product in our range that is not vegan. If you need a vegan hair routine, look for masks built on plant proteins, such as wheat or rice, without keratin.

Last reviewed: October 2026.