Home Cosmetic Science Talk Formulating What causes precipitation in this shampoo formula?


  • What causes precipitation in this shampoo formula?

    Posted by abdullah on January 23, 2024 at 11:11 pm

    This is my shampoo formula

    60% SLES liquid ( 12% AS)

    7% CAPB (2.1% AS)

    2% amodimethicone micro emulsion ( 0.5% active)

    0.2% cationic guar

    1% nacl pre dissolved in water


    Citric acid




    pH 5

    Method: mix cationic guar with water, add CAPB , then citric acid and EDTA, then amodimethicone micro emulsion , then SLES liquid then fragrance and preservative, then NACL to adjust viscosity.

    After only one day, there are some precipitations as you can see in pictures.

    What is precipitating, what is the cause and how can i solve it?

    abdullah replied 1 month ago 3 Members · 8 Replies
  • 8 Replies
  • ketchito

    January 24, 2024 at 6:47 am

    Your system might be salting out. Could you make a batch without NaCl? If that one works fine, you’ll need to add small amounts of NaCl and test if it doesn’t precipitate. You’ll find out then the max amount of NaCl your system can handle.

    • abdullah

      January 25, 2024 at 8:13 am

      It has only one percent NACL. I did make another batch with 0.5% NACL and it was the same.

      Yesterday i did mix them again with high shear mixer and now that precipitation has gone to the top.

      If it is salting, will it only precipitate to the bottom or it can go to the top too?

  • ketchito

    January 25, 2024 at 8:31 am

    Hi @abdullah, long time no see! Check if the precipitate that went to the top yesterday, will settle over time. I believe that will happen since it’s a lot of precipitate shown in your pics. Try one sample without salt and put it in the fridge, to see what happens 👍

    • abdullah

      January 26, 2024 at 10:11 am

      Hi @ketchito

      Thanks for the comments.

      Yes it precipitated again.

      I will make another batch without NACL and see what happens.

  • abdullah

    January 29, 2024 at 9:50 pm

    @ketchito i found the problem.

    I made two batches. One without NACL and one with 1.5% NACL but without amodimethicone micro emulsion.

    The one with 1.5% NACL but without amodimethicone micro emulsion was stable. But the one without NACL that had amodimethicone micro emulsion precipitated again in one day.

    Now that we know the problem is amodimethicone micro emulsion, what should I do about it to prevent it’s precipitation?

    Emulsion is: Amodimethicone (and) Trideceth-12, 3000 cps amodimethicone viscosity, <0.1um particle size, 25% silicone.

  • ketchito

    January 30, 2024 at 5:39 am

    That’s strange. One thing I could suspect is that your microemulsion also has Cetrimonium chloride, and it might be reacting with your SLES. Else, I don’t know what could be happening. If that’s the case, switch to a microemulsion with a purely non ionic enulsifying system.

    • abdullah

      January 30, 2024 at 9:14 am

      No it doesn’t have Cetrimonium chloride. It is clear as it is micro emulsion. The one with Cetrimonium chloride is opaque and it was creaming to the top. This one is going to the bottom.

  • Meemcha

    January 30, 2024 at 6:59 am

    Maybe your method is the problem? Try adding guar at the end, before NaCl. Let hydrate, then add salt. You are introducing a lot of water after the gum has been hydrated.

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