Foaming and Cloudiness in HPMC Serum
Question
I made a serum formulation using 1% Hydroxypropyl Methylcellulose (HPMC) as a thickener, using [url=http://www.myskinrecipes.com/shop/%E0%B8%AA%E0%B8%A3%E0%B9%89%E0%B8%B2%E0%B8%87%E0%B9%80%E0%B8%99%E0%B8%B7%E0%B9%89%E0%B8%AD%E0%B9%80%E0%B8%88%E0%B8%A5-thickener/336-hydroxypropyl-methylcellulose-hpmc.html:3lj7glwr]. When I rub it on the skin, it turns cloudy and foams. I would like to know the cause or if I should adjust the pH first.
Answer
# Understanding Foaming in HPMC Serums
The observation of your serum formulation, thickened with 1% Hydroxypropyl Methylcellulose (HPMC), turning cloudy and foaming when rubbed on the skin is a known characteristic of HPMC.
HPMC is a polymer that has a unique property of helping to create bubbles or foam. This is why it is commonly used not only as a thickener in serums and gels but also in cleansing formulations like shampoos and liquid soaps to create lather.
Therefore, the foaming you are experiencing is likely due to the inherent nature of HPMC itself, especially at a 1% concentration which provides significant viscosity and gel structure.
Regarding pH adjustment, HPMC is generally stable and effective across a wide pH range, typically from 3 to 11. While maintaining an appropriate pH for your overall formulation is important for stability and skin compatibility, adjusting the pH within this range will not eliminate the foaming caused by the HPMC.
In summary, the foaming is a natural outcome of using HPMC as a thickener, particularly when the product is agitated or rubbed on the skin.
