microfoam on hand sanitizer

Hi fellow chemist, I have problem about making simple hand sanitizer. The texture of the gel, clarity, and aroma is good. However when I rub it on the hand, it forms micro foam which is not pleasant at all. Eventually when totally dries, the micro foam is gone, but still the micro foam is a problem.

Here is the formula:
To 100 Purified Water
70.0 Ethanol
0.2 Carbopol 980
0.2 Fragrance Oil
TEA (only 4 drops)

My method is to combine first the carbopol with water until it is transparent, then I add TEA to thicken it. Then I add the ethanol slowly until everything is mixed properly and turn to light gel consistenty. I add Fragrance oil in the last step.

Do you have any idea what cause the micro foam? I thought at first 60% ethanol is not enough, so I changed to 70% hoping that the foam will not form. But still at 70% the micro foam is very visible. My benchmark product has the same ingredients, although the composition may differ.

Thank you so much and hope to get your insight about this problem.
Regards,
Vincent

Comments

  • Try carbopol 21
  • Andraous said:
    Try carbopol 21@ 0.3%
  • Hi @Andraous . Thanks for your insight. I did right away trying what you suggest which is using other carbomer.

    I tried Carbopol Ultrez 20, with same formula and input rate. However it turns out to form microfoam even more. It is even more unpleasant.

    Do you think think Ultrez 21 will be different? Sorry I cannot find ultrez 21 in my region, thats why i decided to try ultrez 20.

    Thanks so much 

  • chemicalmattchemicalmatt Member, Professional Chemist
    Better yet, use RapidGel EZ-1 (3V Sigma). It drops right in, no pilling, no foaming, no problem. 
  • @chemicalmatt i cannot source that in my region.. carbopol series available in my area are 980, 940, 990, ultrez20, ultrez21. Maybe i can get more if I contact directly to the factory, but it is impossible as I cannot afford to buy big quantities at this stage

  • chemicalmattchemicalmatt Member, Professional Chemist
    @vhogiono ; In that case, use Ultrez-21, its  the best for that application. Your "microfoam" can only be originating from the fragrance BTW. It must have a surfactant solvent/fixative. 

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