Home Cosmetic Science Talk Formulating Advanced Questions VISCOSITY ALERT!!!


    Posted by filiz on September 18, 2020 at 5:12 am

    Hi everyone…

    ı study a shower gel but I can not adjust it’s thickening. 
    I know about the salt curve. that’s why I set the COCAMIDE DEA and salt amount not to exceed 4% in total.

    SLES 14
    DEA 2
    GLYCERIN 0,5
    VITAMINE E 0,1
    PARFUME 0,5
    SALT 1
    COLOR 0,02

    there is no need adjust the pH with citric acid. pH=5,4
    the range ı want is 5,5-6

    ı would appreciate it if you could help me find the problem affecting thickening badly. I need some advice. Thank you.

    filiz replied 3 years, 9 months ago 3 Members · 6 Replies
  • 6 Replies
  • ketchito

    September 18, 2020 at 12:20 pm

    @filiz You can increase the SLES a bit, or the Betaine, or the Sodium chloride. 

    Also, you don’t want to go too down on pH, since Betaine would behave as a cationic and react with the SLES (don’t go lower than 6). Actually, you can test if a raise on pH would increase viscosity. Do you want your pH range to be between 5.5 - 6.0 for an specific reason?  

  • filiz

    September 21, 2020 at 6:20 am

    Hi @ketchito thank you

    The pH range I have determined is 5.5-6. however, after adding the salt before it reached this range, the pH = 5.4. I thought I had reached the maximum amount of salt I could add. because the sum of the DEA and salt ratio should not exceed 4%. as a result: I made the salt 1.5. but it didn’t work.

    At the same time, the thickening deteriorated suddenly with the 0.5% salt I added. 
    My biggest problem is not getting the thickening.

  • ketchito

    September 21, 2020 at 1:01 pm

    @filiz I recommend you to approach a pH of 6 before adding the Betaine. You might notice an increase in viscosity compared to your other formulas, since Betaine will be mostly in the zwitterionic state and interact better with SLES, allowing you to add less salt to reach your viscosity. 

    If this doesn’t work, try to either increase SLES (1 or 2% increase would be fine), or increase Betaine (1% would be ok). In both cases you’ll notice an increase in viscosity without much salt compared to your previos tests.

  • filiz

    September 24, 2020 at 5:15 am

    thank you for your help @ketchito

    I increased the amount of betaine and removed AQUAXYL.

  • chemicalmatt

    September 25, 2020 at 6:22 pm

    Just an addedendum here @filiz  since @ketchito called it right. The classic ratio of surfactant build in formulas such as these is 4:2:1 anionic:amphoteric:alkanolamide. Increasing ampho ratio generally -but not always- will build viscosity even more until you have a gel on your hands. I rarely need to add NaCl.  Also you found out on your own that deleting polyols like Aquaxyl (and glycerin - DEL that too) increases your viscosity. Good lesson to learn! Friends: stop adding glycerin and other polyols to body washes, shampoos and shower gels. All it does is kill viscosity and reduce foam.  

  • filiz

    September 28, 2020 at 5:31 am

    @chemicalmatt thank you for explain… 

    I developed the formulation further. 

    I added C12-13 ALKYL LACTAT instead of DEA. I fixed the foam with polyquaternium-7. I think I reduced the effect of my foam by adding 0.5 instead of removing the glycerin completely. The result is pretty good. the only problem is the pH is highly variable. I worked 4 parallel and the salt ratio I needed to add changed a little.

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