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The truth about silk and cashmere proteins

Laura`s Questions:

Question 1:

Products such as Softsoap’s Pure Cashmere line claim to contain a cashmere extract, taken from protein in goat hair oil. Does this sound plausible?

Answers From The Right Brain:

Yes, it’s plausible. Protein is a natural ingredient derived from animals (from skin, hooves, horns, and hair) and from vegetables. Cashmere extract belongs to the class of proteins extracted from animal hair; goat hair to be precise. In fact, goats have two layers of hair and the softer, inner hair is what we know as cashmere. The technical name for this ingredient is hydrolyzed keratin (sometimes called hydrolyzed wool. I’ll explain what hydrolyzed means in a minute.)

Question 2:

Some products contain hydrolyzed silk protein. Is this product common in hair products?

Answer: Yes, many cosmetic products use silk protein as a featured ingredient. And silk protein, as the name implies, is extracted from silk. As in silk worm cocoons. Or spider’s silk.

Question 3:

What benefits would the cashmere extract likely have? Would it prevent moisture loss? Soften skin? Would this cashmere be considered an oil?

Question 4:

What specifically does silk protein do? (I’ve read it temporarily fills cracks in the hair shaft, but I’m not sure what this means.) Would this silk protein have a sealing effect on dry skin? If so, how and why?

Answers: Here’s where it gets tricky. In theory, proteins can help moisturize skin and smooth hair because hair and skin are also made of protein and because proteins are large molecules that are able to form films. By forming a film they can retard moisture loss, much like the skin that forms on pudding.

However, in practice, proteins are not very effective moisturizing ingredients. That’s because in their native form, they are very large molecules and they are not easy to incorporate into body washes or shampoos. So, the chemical companies that sell proteins have to break them down into smaller units that are more water soluble and therefore easier to work with. This process of breaking big proteins into smaller pieces is called “hydrolysis.” The good news is hydrolyzed proteins are easier to put into formulas. The bad news is, they aren’t very effective because making the molecules smaller causes them to lose much of their film forming properties.

Another reason that proteins aren’t very effective is that they won’t stick to hair very well from a rinse out product (like a shampoo or a body wash.) There are special proteins (called quaternized proteins) that are chemically modified so they’ll stick to hair and skin better.

Does all this mean that Softsoap and other products that use proteins don’t really moisturize hair and skin? No, not at all. It just means that the proteins are not really the functional ingredients doing the moisturizing. That’s a common game that the cosmetic industry plays. Manufacturers try to differentiate their products with “sexy” sounding ingredients. In reality, it’s usually the formula as a whole, and not any specific ingredient, that’s getting the job done.

Comments on this entry are closed.

  • KCB GUPTA October 18, 2015, 5:17 am

    Nicely explained about this silk protein, which does not extend any benefit when added to Poos. But it is used as a marketing gimmick by cosmotic mfrs.

  • Joseph Tucci February 16, 2017, 12:43 pm

    Hello: I am wanting to purchase hydrolized keratin, hydrolized wheat protein and Hydrolized silk protein. I would like to add the concentrates to hair color or conditioners for my hair salon. My question to you is would it be beneficial to do this and what proportions would I use?

    • Randy Schueller February 17, 2017, 7:53 am

      I don’t think you’ll see much benefit from adding this ingredients to your formula.

  • Osemerr Avery January 11, 2018, 2:18 am

    Hi, I read your response on adding hydrolyzed proteins to shampoos and conditioners, but would it be more affective in a leave in conditioner?

    • Perry Romanowski January 12, 2018, 10:22 am

      Yes, it would be more effective in a leave-in product.

  • Andrzej S. January 15, 2019, 6:40 am


    If this is true, then why people with wavy/curly hair, when not using conditioners with proteins (but using conditioners with emollients and humectants) for a while, have their hair less curly, less defined? Their hair return to normal after deep conditioning with some product that contains hydrolyzed proteins. And if proteins are used to frequently, hair become very dry like a hay, light like a feather, matte, with many fly aways, hard to style and in worst cases hair crumbles?

    I read on some science-based hair-care blog that proteins are slightly cationic at lower than neutral pH (around 5 is best) so they’ll bond to hair. They’re most substantive when their molecular weight is about 1000 daltons or less and smaller than 500 daltons can penetrate into the hair.

    Or maybe Slavic hairs (delicate and soft) are just protein sensitive and can benefit from proteins or make them worse if overproteined?
    Anyway, these are my and thousands of people with wavy/curly hair experiences.

    • Perry Romanowski June 15, 2019, 12:48 pm

      There are lots of explanations and any individual is difficult to explain. We report what controlled scientific research says. Anecdotal evidence is just not reliable.

  • Lavern Evans February 10, 2019, 6:08 pm

    Is it safe too use over a long durations
    And what do you think about beekman products

    • Perry Romanowski February 11, 2019, 8:03 pm

      Sure, silk is fine to use over long durations. I don’t know, I’m not familiar with Beekman products.

  • Sophia Emmanuel February 17, 2019, 11:52 am

    Thank you for clarifying this in such an easy way we as consumers can understand.

  • Hinda Moore January 3, 2020, 5:35 pm

    Which products have quaternize proteins as for shampoo, conditioners and leave In conditioner or daily hair dressing creme or moisturizing lotion for hair.. Other than that are there other option such as (diy)at home.. Thanks

  • Jodie Marie April 13, 2020, 3:24 am

    How do you know which protein your hair needs? There are so many and different from others

    • Perry Romanowski April 13, 2020, 6:45 pm

      Proteins delivered from rinse out products will all have the same effect on hair which is not much. But the type you pick will not matter.