Home Cosmetic Science Talk Formulating How much to dilute 70% SLES gel so it becomes liquid?

  • How much to dilute 70% SLES gel so it becomes liquid?

    Posted by Gunther on August 1, 2018 at 1:23 am

    Dilute it by half, down to 35%? 30%
    Do you need a preservative when it becomes liquid?

    DAS replied 6 years, 3 months ago 7 Members · 7 Replies
  • 7 Replies
  • em88

    Member
    August 1, 2018 at 6:13 am

    There are commercial SLES solutions at 26-27% which are liquids. My guess it should be liquid even at 35%, but it should be tested. 
    Regarding preservatives, I’ve seen without, but I guess it depends on the shelf life. 

  • Bill_Toge

    Member
    August 1, 2018 at 8:00 pm
    between around 30 and 65% w/w it forms a crystalline phase which is completely rigid, and much harder to process than the lamellar phase it forms at 70% and above - this is why it’s sold as 70%, 28% or lower
    whether or not it needs preservatives depends on the pH of the dilution; dilutions without preservatives are around pH 12, and use their high alkalinity as preservation
    in my experience, industrial-scale dilution tends to be carried out using a specialist (and complex) Bran-Luebbe mixer like this one
  • Fekher

    Member
    September 12, 2018 at 6:40 pm

    @Gunther for sure it needs preservative

  • ZivBA

    Member
    September 13, 2018 at 7:03 am

    When SLES70% is converted into SLES27%, it diluted by a lot of water,
    At the same time the osmolarity of the solution decreases, due to a lower concentration of salts,
    Which gives room for bacterial growth.

    In my factory we consume large quantities of SLES70%, and sometimes in the winter we use SLES27%.
    Solutions of SLES27% are manufactured according to factory orders and are with the same preservation system as the plant uses and at its request.



  • jeremien

    Member
    September 13, 2018 at 10:22 am

    Bill_toge is right, at around 30% in water SLES form an hexagonal liquid crystalline phase that is very viscous. The concentration limits of the phases may vary a lot depending the impurities contained in the different batches of SLES.  I guess that the hexagonal phase is present in a large range of temperature (is is the case for SDS not sure with SLES).

  • Gunther

    Member
    September 13, 2018 at 3:08 pm

    @jeremien so that means that SLES is still viscous at 30%, so you’d need to dilute it down to 27% or less for it to become water-thin ?

  • DAS

    Member
    September 13, 2018 at 3:41 pm

    @jeremien yes, SLES will also get gummy at low temp. Specially the natural type. 

    @Gunther that’s why is usually sold at 25%, it remains liquid. If you are buying higher concentration, if the supplier doesn’t give you the COA is usually watered down.

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