Updated: Feb 24
In this Vol, we will cover:
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The pH scale
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Testing pH
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Adjusting pH.
THE PH SCALE
pH is the measure of acidity and alkalinity.
The pH scale ranges from 0-14.
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The centre of the scale, 7.0, is neutral.
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Above 7 is classified as alkaline.
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Below 7 is acidic
The skin has a slightly acidic pH, ideally pH 5.5. It can range from pH 4.5-6.5 depending on your skin’s chemistry and the type of products you have been using on the skin. Usually, cosmetic products will have a pH somewhere between 4.5 and 5.5.
It is not only mandatory that the pH of the cosmetic products remain in a certain range to guarantee consumers’ safety, it is essential in product stability, and most importantly, in natural cosmetics it is essential for the performance of the preservative system you are using.
TESTING PH
The pH of a product can be quickly and easily tested by using a pH strip. pH meters are also available but these are more complicated to use, so when you are starting out we recommend using pH strips.
You only need to test the pH of products that contain water
When making emulsions you can spread a little of the emulsion onto your pH strip once you have added the cooling phase. You then need to wait one to two minutes for the strip to show the pH. When creating simple emulsions such as the ones featured in this course, to make pH adjustment easier, you can check the pH of the water phase (before mixing it with the oil phase). Dip the pH strip into the water phase, read the strip and adjust the pH. After adding cooling phase ingredients into the emulsion, retest the pH. Usually there is no big change in the pH and there is no need for further adjustment. This method is faster, because the pH strips change color immediately in the water and can be read straight away, as opposed to waiting a minute or two, when testing the emulsion.
