Home Cosmetic Science Talk Formulating Skin Syndt Bar vs Soap?

  • Syndt Bar vs Soap?

    Posted by prizes2011 on August 17, 2015 at 4:11 pm

    What are the scientific reasons for using a syndet bar over traditional alkali soap? I know pH is the main reason, but what else? Does aging a soap making a difference or is it just marketing? Thanks!

    RKB replied 8 months, 2 weeks ago 10 Members · 19 Replies
  • 19 Replies
  • belassi

    Member
    August 17, 2015 at 4:51 pm

    1. None, in fact the reverse.

    2. Yes it does.
    • RKB

      Member
      August 7, 2023 at 2:16 pm

      Belassi, I know this is an old post, but I just came across it. Can you talk a bit more about soap over syndet? I usually see people prioritizing syndet.

      • PhilGeis

        Member
        August 7, 2023 at 2:51 pm

        Syndets last century were marketed on the basis of eliminate soap scum the hard water Ca salt of soap fatty acids - and were less irritating than C12 coconut fatty acid bar soaps.

        • RKB

          Member
          August 8, 2023 at 12:13 am

          Hi Phil. Thank you for your response. And forgive me if this is a dumb question because my brain tends to be really literal and sometimes I misread things because of it. But were the comparisons done to coconut oil-only soap rather than blends intended to soften the harsh effects of saponified oils like coconut?

          • PhilGeis

            Member
            August 8, 2023 at 5:37 am

            Any fatty-acid based soap. P&G advertised its Zest against its own (but unnamed) Ivory soap. Lever advertised its Dove vs the same (also unnamed) Ivory for “mildness”.

            • RKB

              Member
              August 9, 2023 at 12:08 pm

              Thank you for all that, Phil!

  • prizes2011

    Member
    August 17, 2015 at 7:35 pm

    Certain surfactants are suppose to be better for skin than soap. You know like Vanicream’s cleansing bar. 

  • belassi

    Member
    August 17, 2015 at 8:29 pm

    Please define “better”. In what way?

  • prizes2011

    Member
    August 18, 2015 at 12:53 am

    Most cleansing bars are based off Sodium Cocoyl Isethionate, a very mild surfactant that doesn’t damage the acid mantle or remove protective lipids like alkali soap. Are you a chemist? 

  • Microformulation

    Member
    August 18, 2015 at 1:22 am

    The lower pH of a syndet bar is thought to be better for the skin mantle, although any disruption is minimal.

    Syndet bars will perform better in hard water.

  • prizes2011

    Member
    August 18, 2015 at 1:29 am

    And I know different oils have different drying effects when saponified. What oil would be most gentle in that regard, in your opinion? My guess would be canola, olive, or Shea. 

  • David08848

    Member
    August 18, 2015 at 1:16 pm

    As a soapmaker, I have made myself aware of the fatty acid structure of all the oils and exotic butters I use in my soaps.  Many surfactants are also made from fatty acids and each one of them has a certain characteristic as a result.  Oleic Acid creates a soap that is more mild than other fatty acids.  Olive oil contains about 80-82% oleic acid and as such is considered mild when it is made into a soap whether it is with sodium hydroxide or potassium hydroxide.  I use olive oil in many of my soaps and I also use Oleic Acid in my liquid soap for that same purpose.  Keep in mind that is is the percentages of these oils in a blend that makes the difference.  If one were to use a high percentage of Coconut oil then the resultant soap would be irritating/drying to the skin but in a small percentage coconut oil can produce great lather.  Keep in mind that the balance of these oils is what created a long lasting, lathering and gentle soap!

  • OldPerry

    Member
    August 19, 2015 at 2:11 pm

    I’m not sure that this is a scientific question.  It’s more of an aesthetic question.

    The primary purpose of these cleansing bars is to clean the skin.  Both soap and syndet bars will do that.  You could do a lab test to see which cleans better but for most purposes the only thing that matters is what consumers think cleans better. I’d say consumers would generally have a tough time determining whether a syndet bar or soap bar cleans skin better so it’s really a wash (pun intended).
    But consumers like their skin to feel good and when it comes to irritation the reality is that syndet bars based on something like Isethionate are more mild than Soap.  Read this chapter.  Syndet bars are superior here.
    Syndet bars can also be made to foam in all types of water where soap doesn’t foam as well in hard water.  So syndet bars are superior here.
    Like I said, it is not really a scientific question but based on what I think makes a product that consumers would want to use, syndet bars win.
  • Bobzchemist

    Member
    August 19, 2015 at 2:46 pm

    Please also bear in mind that for soaps, “gentle” is exactly the same thing as “Less Effective Cleaner”. A “harsh” soap cleans off all the dirt and oil that should be cleaned off, but also takes off the sebum, etc. that should be there, leaving the skin dry and possibly rough. A “gentle” soap leaves oil behind, but also some of the dirt and debris that possibly should have been cleaned off.

  • BartJ

    Member
    August 20, 2015 at 9:02 am

    As another soap maker…
    That’s my tool of reference:
    http://soapcalc.net/calc/soapcalcWP.asp

    You can check the properties of canola, olive and Shea there. You can see that they are different chemically, although marketing-wise, they are all labelled as ‘moisturising’ and ‘good-for-the-skin’.

  • OldPerry

    Member
    August 20, 2015 at 12:23 pm

    @BartJ - cool tool.

  • pma

    Member
    August 21, 2015 at 11:03 am

    It also depends a lot of your surfactant system in your syndet. I’m sure that a sodium lauryl sulfate base syndet could dry out the skin even more than many soapy based cleanser bars.

  • prizes2011

    Member
    September 3, 2015 at 7:30 pm

    Okay, but Sodium Cocoyl Isethionate is still a better choice for skin health? 

  • Bobzchemist

    Member
    September 3, 2015 at 10:09 pm

    Perhaps you should try saponifying a few different oils, and find out for yourself?

Log in to reply.