Home Cosmetic Science Talk Formulating liquid soap composition

  • liquid soap composition

    Posted by chemistgr1 on October 22, 2018 at 11:18 pm

    I read the article on body wash composition, but I still need some help here!!! 

    I formulate a liquid soap based on the classic recipe (oil + KOH + citric acid to reduce the pH). I noticed that without any additional compounds, the odor and the color of the liquid soap change or diminish by time. Also the foam is not that rich and the pH is only reduced up to 9. 
    Is there any surfactants or any other additives :

    1. To stabilize the odor and color 
    2. To further reduce the pH to 7 or below
    3. To increase the foam. 

    And in which percentage w/w or w/v ?
    Finally, all the additives (surfactants or colorants or chelants or thickening agents) are all added at the final product or during saponification and in which stage?
    Thank you for your response.
    OldPerry replied 5 years, 7 months ago 7 Members · 12 Replies
  • 12 Replies
  • ngarayeva001

    October 23, 2018 at 1:17 pm

    Classic soaps are drying. If you formulate a liquid product anyway, maybe you consider making it with surfactants instead? I am talking about a product made of SLES and Non-Ioninc/Amophoteric surfactants. You can bring the pH to 6 and have a nice foam.

  • belassi

    October 23, 2018 at 2:46 pm

    Saponified oils … it is what it is. The reason it slowly changes is that you have a mixture of soluble and insoluble soap compounds, it is not a stable product.
    Using citric acid to reduce the pH will result in separation into FFA’s and water, quite unpleasant.
    The answer to all your problems is to use synthetic surfactants.

  • chemistgr1

    October 23, 2018 at 3:45 pm

    Thank you all the answers. The reason I use oils- the traditional way- is that my clients want a natural (as far as it gets) liquid soap. 
    Let’s say that we can’t change the pH to less than 9, what about the other properties that I mentioned?
    do you think that if I add an amphoteric surfactant, an anionic one, xantan gum or a chellant and preservative I could potentially retain the odor and color and produce a little more foam? 

    Thank you again for you responses.

  • Gunther

    October 23, 2018 at 4:15 pm

    The problem is that if pH is too low (it is too acidic),
    soap begins to decompose back to the water-insoluble free fatty acids
    being insoluble, they separate
    usually rising to the top.

    You mentioned an odor change
    so it looks to me like you are using unsaturated oils which oxidize and decompose
    To avoid that from happening please consider using saturated oils, like coconut.
    You can also buy hydrogenated oils.

  • OldPerry

    October 23, 2018 at 4:16 pm

    If you add an anionic surfactant and an amphoteric surfactant then get rid of the Oils and KOH, you’ll produce better foam & a better product. 

    But sure, you can try adding those in small amounts to improve the performance of your product. (Betaine, SLES, Glucosides) It’s not going to be much improvement because you are starting with ancient technology.

    It’s a decision you have to make then adjust your expectations of performance. You can give your clients an inferior product based on tradition, or a superior product based on science. Trying to turn a saponified oil product into a standard cleanser is like trying to turn a rotary, landline phone into an iPhone.

  • ngarayeva001

    October 23, 2018 at 8:23 pm

    I am pretty sure that you can achieve your marketing story with surfactants. Just don’t use sulfates. You will get much better product. Use ingredients like coco betaine, coco glucoside, thicken it with xantham and label it ‘natural’. It’s not really defined anywhere.

  • Fekher

    October 24, 2018 at 12:45 pm

    @chemistgr1 For soap you can use TEA to have lower ph compairing to KOh and NaOh you can also increase to degree of greasing to have softer soap but increasing greasing will make liquid soap opaque , about foam you just need to use the adequat oils to give better foam no needs to have any other add.

  • chemistgr1

    October 25, 2018 at 9:26 am

    thank you all for your answers! I will consider the facts and try to evolve further your precious knowledge at my work. 

  • ngarayeva001

    October 25, 2018 at 1:09 pm

    @chemistgr1, I can suggest you to have a look at this product (as a referrence)


    It is marketed as organic and parabens free. The LOI:

    Aloe Barbadensis Leaf Juice(1), Aqua (Water), Coco-Glucoside, Glycerin, Sodium Laurylglucosides Hydroxypropylsulfonate, Heptyl Glucoside, Decyl Glucoside, Xanthan Gum, Citrus Aurantifolia (Lime) Oil, Citrus Limon (Lemon) Peel Oil, Lavandula Angustifolia (Lavender) Oil, Calendula Officinalis Flower Extract(1), Chamomilla Recutita (Matricaria) Flower Extract(1), Chenopodium Quinoa Seed(1), Lavendula Angustifolia (Lavender) Flower/Leaf/Stem Extract(1), Tocopheryl Acetate, Bisabolol, Citric Acid, Inulin(1), Sodium Chloride, Alcohol(1), Benzyl Alcohol, Potassium Sorbate, Sodium Benzoate, Coumarin, Limonene, Linalool

  • mikethair

    October 26, 2018 at 9:24 am
    We do a lot of liqiud soap the classic way (oil + KOH). In response to some of the comments:
    “the foam is not that rich” - different oils have different characteristics and level of foam. For example olive oil = low foam, coconut oil = high foam. We blend a few oils to get the characteristics we want.
    “the pH is only reduced up to 9.” - ours are usually around 9.5 and we do not adjust with citric acid etc. Bring the pH down too far and you may then need to consider using a preservative. Will also tend to cause some seperation.
    “Classsic soaps are drying.” - a sign of poor saponification methods/calculation. Our customers say different. With many recipes we super-fat.
    ” it is not a stable product.” - not in our experience. As part of our compliance requirement we retain product samples. After 4-5 years, products are still OK.
    “the traditional way- is that my clients want a natural (as far as it gets) liquid soap.” - our experience exactly. We also produce for other brands as well./

    “You can give your clients an inferior product based on tradition” - then I wonder why this inferior product is in such high demand. I will add however, this tradition is not easy.
  • ngarayeva001

    October 26, 2018 at 2:32 pm

    There always will be a market for soap. Many  people love that squeaky feel. They have a feeling that such a product cleanses better. I have not used soap on my hands for years (and on my face for more than 10 years). Maybe they are better now.

  • OldPerry

    October 26, 2018 at 2:48 pm

    @mikethair - “inferior” is merely my opinion and refers to the complaint in the initial comment that “foam is not that rich.” 

    If you did a laboratory evaluation of the foam density of the best made soaps versus the best made modern surfactants, the new technology would win.

    Since your customers like your product, then your foam quality is sufficient to match their expectations. They obviously don’t share my opinion that the performance is inferior.

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