Home Cosmetic Science Talk Formulating lowest pH at which SLES can be stable Long term

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  • lowest pH at which SLES can be stable Long term

    Posted by abdullah on October 5, 2021 at 6:59 am

    I want to make shampoo at lowest pH possible. Below pH 5

    What is the lowest pH at which ALS,SLES, CAPB and lauryl Glucoside can be stable Long term specially SLES? 

    abdullah replied 2 years, 5 months ago 3 Members · 8 Replies
  • 8 Replies
  • ketchito

    Member
    October 5, 2021 at 1:19 pm

    @Abdullah SLES due to the presence of an ether group, might be the more sensitive of that group. I remember some degree of hydrolisis might occur below a pH of 4 (at higher pH, some hydrolisis can also occur, it’s so little and slow that it becomes irrelevant). That’s why acid cleansers don’t use SLES. 

  • abdullah

    Member
    October 5, 2021 at 2:07 pm

    @ketchito so what anionic surfactant should we use in acid cleanser? 

  • ketchito

    Member
    October 6, 2021 at 1:16 pm

    @Abdullah I’ve seen Sulfonates (like AOS) as very common anionics in low pH products.

  • abdullah

    Member
    October 6, 2021 at 2:12 pm

    @ketchito what about SLS and ALS?

    I will not formulate in very low pH. Any pH below 5 at which SLES can be stable is good.

    How do you know if hydrolysis is happening so i can check up to what pH it is stable? 

  • bill_toge

    Member
    October 6, 2021 at 7:25 pm

    in my experience, SLES is stable down to pH 3 (not tried any lower than that) - if the acid is non-nucleophilic, e.g. citric or lactic, ethers can’t easily be hydrolysed

  • abdullah

    Member
    October 7, 2021 at 2:54 am

    @Bill_Toge thanks.
    What about salicylic acid? 

  • bill_toge

    Member
    October 7, 2021 at 7:28 pm
    again, it’s effectively non-nucleophilic, so it’s likely to have minimal if any reactivity
    it’d be quite a different story if you were using hydrobromic or hydroiodic acid
  • abdullah

    Member
    October 8, 2021 at 1:18 am

    That’s Bill

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