Home Cosmetic Science Talk Formulating Viscosity problem


  • Viscosity problem

    Posted by Larissa9 on September 19, 2020 at 5:51 pm

    Hello everybody,
    I am on my final year of Pharmacy college (read: no experience) and working on a gel with glycolic acid and suspended olive pit particles that are suposed to work as mechanical body peeling. When I make this gel everything looks great for maybe two weeks then olive pits start to sediment. I chose a pH of 3 and currently considering to make it 3,5.
    This is what I have now;

    Aqua purificata 79,56%
    Glycolic acid (70%) 5,72%
    NaOH 0,42%
    Hypromellose 2%
    Xanthan gum 1%
    Olive pit particels (500, Fagron) 1,2%
    Cocamidopropyl betaine 9%
    Vitis viniferae 0,4%
    Aurantii aeth 0,7% 

    How do you think I can stop sedimentation?
    Thank you very much for your help.

    Larissa9 replied 3 years, 9 months ago 2 Members · 2 Replies
  • 2 Replies
  • Pharma

    September 19, 2020 at 6:45 pm

    If sedimentation is caused by a progressive viscosity loss, raising pH might be the solution. pH 3 is the lower end of stability for both polymers and I’d guess it’s hydrolysis of these which would be responsible for said viscosity loss.

  • Larissa9

    September 19, 2020 at 7:14 pm

    Thank you for your suggestion, makes sense.
    I will try with pH 3,6 which is also the pKa of glycolic acid and see what happens.

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