Home Cosmetic Science Talk Formulating Advanced Questions cationic surfactant in a shampoo bar -possible or not?

  • cationic surfactant in a shampoo bar -possible or not?

    Posted by Unknown Member on January 13, 2024 at 12:16 pm

    Hello everyone,

    I have a question regarding shampoo bars composed of powder/needle anionic surfactants containing cationic surfactants. During my cosmetic chemistry studies I learned that we should not combine cationic and anionic substances - does this rule apply also to solid cleansers?

    There are many sources, including professional brochures from cosmetic ingredient suppliers, which have exemplary formulas combining these two types of surfactants. I am confused and I would be very grateful if you could share your expertise in this matter…

    Best wishes to all.

    Anca_Formulator replied 1 month ago 4 Members · 3 Replies
  • 3 Replies
  • fekher

    January 13, 2024 at 2:01 pm

    I guess you can do it, almost liquid shampoo contains both cationic and anionic surfactants.

  • ketchito

    January 15, 2024 at 8:56 am

    There are some excepcions to the rule of not mixing cationic surfctants with anionic surfactants. There are few papers on the matter. But in the case you mention (solid bars), they do it so you can get a hard smooth bar. Now, I don’t see much issue there since when you lather, SCI for example, will rapidly dissolve in water, while Behentrimonium methosulfate will not, so they won’t actually meet, or at least not to cause a dramatic loss in foam or performance. The cause would be different if you add Cetrimonium chloride to a shampoo that has quite some SLES, forming precipitates when they meet.

  • Anca_Formulator

    January 27, 2024 at 12:22 pm


    I was struggling with the same questions recently, but learned (from Susan Barclay Nichols, aka Swift Crafty Monkey) that you CAN mix anionic with cationic in SOLID formulations that do not contain water. If you try to mix them in a liquid cleanser, you get a complex/precipitate, as ketchito said.

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