Using fresh lemon or lime juice in soap..?

Discussion in 'Lye-Based Soap Forum' started by Jerry S, May 14, 2011.

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  1. Jul 22, 2019 #61

    StoneCottageSoapworks

    StoneCottageSoapworks

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    Earlene,

    Yes, you are correct that adjustments need to be made to a formula when you add an acid that will affect the base used in the product, but you said very little about how you made the calculations to correct the addition of an acid to the base included in your formula. In the 2nd. portion of my response, I was responding to the scent aspect mentioned below by the original poster, Jerry who created this thread to find out the information about using lemon in his soapmaking process. My reply, as others who have replied to this thread, is to everyone who has posted or who is reading this thread.

    Sorry I didn't delete the second section of your post. You are entitled to express your opinion about the pH of soap as you did in the 3rd. section. I don't happen to feel the same way about this issue. I am very careful in determining pH in soap, shaving soap, shaving cream or any other types of products I formulate and manufacture. I have been taught by several friends of mine who are cosmetic chemists how important it is to test the pH of a product if there is any concern about it having a higher pH than is appropriate for that product. I was instructed that I should use a pH meter (and I do feel much more comfortable using my pH meter!) to do the appropriate testing as it is the only proper way to perform this task! I am saying this to all those out there who may read it as I think it is important and correct information for them to have so that they can do the right thing when they are creating their products! This goes for amateurs and professionals alike! :)
     
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  2. Jul 22, 2019 #62

    DeeAnna

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    Most people expect way too much out of a pH test, especially when it comes to soap. Most soap makers want the pH test to tell them whether their soap contains excess alkali when they pH test their soap.

    Problem is, the pH test is not sufficiently precise enough to give you a useful answer. Only a few parts per thousand of excess alkali means the difference between skin safe or not, and a simple pH check cannot come close to telling you this.

    The other aspect is that the pH of a fully neutralized soap will vary with the fatty acids present in the soap. One soap that tests at a pH of 10.0 might be skin safe and another soap testing at a pH of 9.5 might contain excess alkali.

    For both of these reasons, it is unwise to depend on pH for confirmation that the soap is skin safe (no excess alkali). A titration test for free alkali is the gold standard procedure that answers this question accurately. The quick qualitative check of excess alkali is the zap test.
     
    Last edited: Jul 22, 2019
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  3. Jul 22, 2019 #63

    cmzaha

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    I remember reading a chart on the mildest rated soap for babies several years ago and one of the highest ph soaps was rated the mildest. Someone here might remember the article, I just do not.
     
  4. Jul 22, 2019 #64

    earlene

    earlene

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    Hmm.

    but you said very little about how you made the calculations to correct the addition of an acid to the base included in your formula. [/QUOTE] No, as it has already been covered elsewhere. Refer to post #14 for instructions how to do so as I would have said had a new person asked.


    That was not apparent to me. Since you quoted me specifically and then in the very same paragraph said, "Besides, the lemon scent won't "... <snipped the rest for brevity>

    Perhaps I need to learn to read between the lines better.
     
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  5. Jul 22, 2019 #65

    DeeAnna

    DeeAnna

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    That was probably me. The research paper is -- Baranda L, R González-Amaro, et al. Correlation between pH and irritant effect of cleansers marketed for dry skin. International Journal of Dermatology. 2002, 41, 494–499.

    Here is the relevant data from Baranda's article showing the irritation index versus pH values for the commercial soaps they tested. These soaps would not have had excess alkali -- the pH is for the fully neutralized soap. More irritation = higher irritation index. --

    Baranda soap irritation vs pH.jpg
     
    Last edited: Jul 22, 2019
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