Home Cosmetic Science Talk Formulating Sodium cocyl isethionate

  • seaberry

    Member
    July 10, 2021 at 5:50 pm

    Hi! Sodium cocoyl isethionate can be annoying to work with. It doesn’t dissolve well in water or in oil on its own. 

    There are two basic ways to work with it. You can mix it with a liquid amphoteric or non-ionic surfactant, such as cocamidopropyl betaine. It will take a while and maybe a little heat, but they should eventually melt into a smooth paste

    The other way is to use an ethoxylated emulsifier such as Emulsifying Wax NF or Lotionpro 165. It will keep the SCI stable in the formula the same way it would stabilize oils. You may need around one percent emulsifier for every three percent oil. 

  • markbroussard

    Member
    July 10, 2021 at 6:11 pm

    The key to working with SCI is to first grind it into a fine powder.  Add the powder to room temperature water while stirring at 200RPM.  Then begin heating it up to 90C or so.

    It’s best if you use a jacketed container to keep the heat even or immerse the vessel in a hot water bath.  It also helps if you cover the opening to the container … again, it’s all about keeping an even distribution of heat over the entire surface of the vessel.

  • ngarayeva001

    Member
    July 10, 2021 at 7:30 pm

    SCI isn’t meant to be used at any substantial amount in a liquid product. It’s used at 1-3% and if you add more it will eventually precipitate. If you need a similar surfactant that is watersoluble use SLMI. It dissolves at around 80C. Chelator is needed if clarity is important (well chelator is always needed).

  • markbroussard

    Member
    July 10, 2021 at 9:26 pm

    I routinely use SCI at 10% in Shampoos without any issue with precipitation.

  • ngarayeva001

    Member
    July 12, 2021 at 2:12 am

    @MarkBroussard are you using any suspending agents (carbopol aqua sf, etc)? 10% is impressive. My understanding was the max is 7% with yield modifiers.

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