Home Cosmetic Science Talk Formulating Instability in 2 in 1 shampoo


  • Instability in 2 in 1 shampoo

    Posted by DanielleNel on March 17, 2024 at 9:05 am

    Hi everyone,

    I’m studying cosmetic formulation Science and got my first project. I’m very unsure of my answers and would love some help.

    The 2 in 1 shampoo separates at 0C, room temp. and 40C. Separation occurs after 2 weeks at low and elevated temp. The viscosity also drops at these temps. The shampoo has rheology problems and has poor foaming abilities.

    Any help will be much appreciated.

    Kind regards


    DanielleNel replied 1 month ago 3 Members · 4 Replies
  • 4 Replies
  • Perry44

    March 17, 2024 at 2:22 pm

    They didn’t give you an ingredient list? It seems pretty pointless without it.

    I guess they want you to add some HPMC (cellulose polymer). That could help with viscosity, stability & foam.

  • DanielleNel

    March 18, 2024 at 5:01 am

    Only the two formulations in the document I attached.

    Ps. Such a honor receiving a response from you.

  • Camel

    March 19, 2024 at 5:55 am

    @Perry44 I think the document preview is only showing the first page, but if you download the file, there are two more pages which show the formulations and questions. I’m attaching a screenshot if you would like to review them.

    @DanielleNel I am not a chemist, so I cannot answer these questions, but I will take a guess.

    The top layers of both formulas are opaque/hazy because the dimethicone was not properly suspended and/or the fragrance was not properly solubilized. The formulas are not using a water-soluble dimethicone and there doesn’t appear to be anything that would keep it suspended, so I imagine that is the viscous, oily texture forming at the top.

    The pearlescent mica is likely settling at the bottom of the shampoo for the same reason—there is nothing keeping it suspended and/or the viscosity is not high enough to do so. Adding hydroxypropyl methylcellulose (HPMC), as Perry suggested, will likely solve this issue. It can keep the mica suspended while also increasing the stability and foam.

    The foam is likely impaired by the dimethicone, as silicones can suppress foam, but the high fragrance load (1%) may also play a role here. I am usually using around 0.3% fragrance in a shampoo.

    • DanielleNel

      March 19, 2024 at 12:35 pm

      Thank you!

      I appreciate your recommendations 🙏

      and giving me a sound mind knowing I’m on the right tack.

      Kind regards

Log in to reply.