Home Cosmetic Science Talk Formulating Does liquid soap + oils need preserving?


  • Does liquid soap + oils need preserving?

    Posted by jjackson on February 28, 2016 at 2:04 pm

    Hi there, 

    This may be another basic question, and I have researched online and cannot find the exact answer I am looking for. So would appreciate your help and advice. I have made a product which combines oils and butters (e.g. argan oil, avocado butter) with a liquid soap base - do I need to add a preservative? as the oils are anhydrous and the liquid soap doesn’t have (need?) a preservative… If I do, which one(s) would you recommend? 

    The INCI for the liquid soap base is:

    Aqua, Potassium Oleate, Potassium Cocoate, Glycerin, Potassium Citrate, Citric Acid

    Thank you!! Jemma
    belassi replied 8 years, 1 month ago 5 Members · 5 Replies
  • 5 Replies
  • Bobzchemist

    February 29, 2016 at 2:24 pm

    As I’ve said before - EVERYTHING needs a preservative, always.

  • BartJ

    February 29, 2016 at 2:44 pm

    Have a read though the documents I’ve linked in your other topic. If you aspire to be a skincare entrepreneur in our part of the world, you will simply not survive a few months without indepth knowledge of them to see any profit before penalties start rolling in and trading standards officers start knocking at your door. 

    The reason why some liquid soaps get away without preservation is that their pH is above 10.
    In theory only… because a product with pH above 10 would make the skin feel quite awful - notice how whoever invented it went and lowered the pH with citric acid.
    The product is now a disaster, not only it doesn’t perform well, now someone ruined it’s ingrown preservation system with the acid.

  • belassi

    February 29, 2016 at 2:59 pm

    I’ve been wondering about this. If you add citric acid to sodium cocoate to lower its pH you get a snotty mess. It simply doesn’t work. That is why boracic acid (borax) is used, as I understand, for liquid soap. I agree totally with BartJ.

  • David08848

    March 1, 2016 at 1:49 am

    In many cases, an acid is added to lower pH to a more neutral level, but sometimes in soapmaking  a soaps pH is lowered to a less alkaline level to make it more skin friendly but not lowered so much that it will cause oils to precipitate out of the product.  Also, some soapmakers will add more lye in the process to make sure a product is fully saponified and then adjust the pH later.  Make sense, Belassi et al?

  • belassi

    March 1, 2016 at 5:21 am

    Yes. I have been making cold process soap for about 5 years and with the solid soap process it’s easy to allow say 5% superfat allowance and then you’re certain that all the base is converted and the product is skin friendly. As I understand it, and my own experiments confirmed, if you try to superfat with KOH (liquid) soap, then you end up sequestering while the superfat layer settles out, and so on … or you use no superfat allowance (or excess KOH) and neutralise with borax. We still sell CP bar soap but much prefer synthetic liquid soap.

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