Home Cosmetic Science Talk Formulating Shampoo itching and scalp deposition

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  • Shampoo itching and scalp deposition

    Posted by Anna_Maria on May 22, 2023 at 5:55 am

    Hello everyone!

    So i’ve been working on my shampoo formula (2 in 1 conditioning shampoo cold process). It is a very efficient formula that gives a very good after feel for the hair. However, after using the product for a while, you notice itching and some residue scalp deposition. I was thinking about the coacervation mechanism, so i tried to dilute my shampoo (1:10 v:v in water) and i noticed the formation of a white precipitate. I looked about it and it seems its the sulfate-guar reaction that is leading to the formation of this white precipitate.

    Actually i’m a little bit confused, is it normal to have this precipitate? is this is the coacervate? or this precipitate is the reason of the itching and the irritation. How can i know the reason behind this effect?

    I will be sharing the formula and will be very grateful for your help and opinions.




    Cocamidopropyl betaine

    Decyl glucoside

    Guar hydroxipropyltrimonium chloride

    Hydrolyzed wheat protein


    Amodimethicone emulsion (siltech E-4177)

    Salicylic acid (for ph regulation 0.3%) (also i tried citric acid but same effect)



    Sodium benzoate

    Abdullah replied 1 year, 2 months ago 4 Members · 6 Replies
  • 6 Replies
  • ketchito

    May 22, 2023 at 3:41 pm

    Perhaps you could post your full formula, to know if there are ingredients at too high levels. Nevertheless, coacervates are simply speaking precipitates that form upon dilution, which deposit maily in your hair. The size of coacervates is usually small, and your shouldn’t be able to see it too evidently, nor that it causes itchiness. Now, your surfactant system should be powerfull enough to remove most of the coacervate on the next shower.

    By the way, do you use fragrance or essential olis? These are usually involved in contact dermatitis due to cosmetics, and not only can cause itchiness, the could also upregulate the normal cell proliferation and shedding, resulting in a similar flakiness that you see with dandruff.

    • Anna_Maria

      May 23, 2023 at 12:33 am

      When i dilute my shampoo, i can see white filaments that ends up as white insoluble precipitate in the water.

      Yes i use fragrance but i thought about it at the beginning and i tried hypoallergenic fragrance still the same result.

      concerning the ingredients i have:

      SLES 70% : 15%

      CPB 45% : 8

      Decyl glucoside 50% : 5

      Guar: 0.2%

      PQ7: 0.5

      Silicone emulsion 30% : 2%

      HWP powder: 0.2%

      Final formula pH: 5.5

      • ketchito

        May 23, 2023 at 9:18 am

        Yes, when you dilute the product in just water you see the coacervate since in solution it’s able to agglomerate. The story is different when you take a shower, since particles start binding to different sites the moment they start precipitating. And they attach pretty strongly, so you wouldn’t see them fall as shedded cells from scalp do. Now, even hypoallergeninc fragrances can cause some reaction in a person who is sensitive to some component. Why don’t you reast for a few days and try a sample of your shampoo that has no fragrance at all?

        Also, check that your CAPB has only trace amounts of amidoamines, which are known sensitizers.

  • fareloz

    May 23, 2023 at 3:18 am

    The sediment is most likely Salicylic Acid. It is almost insoluble in water.

    • Anna_Maria

      May 23, 2023 at 3:32 am

      i tried with citric acid but still got same result

  • Abdullah

    May 23, 2023 at 11:04 am

    I think thapt guar+ pq7+ 2% amodimethicone emulsion is too much. You can reduce everything by half.

    Can you write the details of your amodimethicone emulsion?

    I couldn’t find it on internet.

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