Home Cosmetic Science Talk Formulating Why the viscosity of sulfate-free shampoo dropped after adding the menthol crystal?

  • Why the viscosity of sulfate-free shampoo dropped after adding the menthol crystal?

    Posted by Anonymous on March 10, 2015 at 7:09 am

    Hi everyone.
    My sulfate-free shampoo’s viscosity dropped after adding the mixture of menthol and fragrance.
    Below is my ingredients.

    Cocamidopropyl betaine
    Disodium Cocoyl Glutamate
    Decyl Glucoside
    Glucamate VLT
    PEG-7 Glyceryl Cocoate
    PQ-7
    Cocamide MEA
    Euxyl PE 9010
    Fragrance
    Menthol - 0.5%
    PQ-10
    Disodium EDTA

    Pls help me to increase the viscosity to 5000cps. Thanks.

    belassi replied 9 years ago 3 Members · 3 Replies
  • 3 Replies
  • bobzchemist

    Member
    March 10, 2015 at 2:11 pm

    Experimentation is one of the keys to success in cosmetic chemistry. I’ll give more details on
    that below.

    One of the others is knowing your raw materials. At a bare minimum, you should have a
    Technical Data Sheet (TDS), a Specification Sheet and/or a Certificate of
    Analysis, and a Safety Data Sheet (formerly a MSDS) for each and every one of
    your ingredients. Ideally, you would have read and kept a copy of all of the
    supplier literature available for every chemical (and not just the literature
    from your supplier) that you are using.

    After you have (at least) read all of the technical data sheets, it should be a little easier to
    fix your formula, For example, in your formula, one of the ingredients that
    provides thickening is Glucamate VLT. Here’s the experimentation part - you
    need to make a series of batches that use increasing amounts of Glucamate VLT
    until you have reached a viscosity you are comfortable with. Then you need to
    duplicate this experiment with any other thickeners you’re using. Then, you
    need to see if any of the thickeners are synergistic with each other. By this
    point, you should be fairly comfortable with using the chemicals that thicken
    your batch, and you will be able to answer your own question.


  • oldperry

    Member
    March 10, 2015 at 2:29 pm

    Experimenting is the key.  You could try using more surfactant, less menthol, less fragrance.  Add a thickener.  Lots you can do but you have to experiment.

  • belassi

    Member
    March 10, 2015 at 3:40 pm

    I’m very familiar with the Glucamate VLT. First, the PEG-7 Glyceryl Cocoate will negatively impact viscosity, I would replace it with glycerin. 

    The menthol and fragrance always will reduce viscosity, you’ll have to increase the VLT to compensate. VLT does not have a linear thickening profile. As you approach the necessary amount, small additions cause large viscosity increases.
    I found that using 1% of cocamide MEA allowed 2.75% VLT. More MEA than 1% precipitated after several days.

Log in to reply.