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What is the adequate way to measure the pH of a cosmetic cream?
I’ve been looking for information about the adequate procedure to measure the pH of cosmetic creams, but I have found conflicting information on the Internet. Some state that the pH should be measured in the cream as it is, while others say that it should be first diluted with water. If the latter is the case, What sense does it make? the pH of a diluted cream won’t be the same when the undiluted cream is applied to the skin. Can you help me clarify this, please? Thanks.
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7 Replies
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Depends on the type and viscosity of the cream.Diluting 1:10 doesn’t change pH in a way that someone in the cosmetics field would bother about. -
So it seems that the more adequate procedure is to dilute the product. It is interesting to see the wide acceptance of this method, a ten-fold dilution makes a significant difference to me, but it’s just my opinion. Since pH measurement depends on the characteristics of the cream, Can you suggest me a reliable book to go deeper into this topic? I produce both, o/w and w/o skin creams with different viscosities.Thank you for commenting -
Nobody uses 10:1 dilutions for pH testing except under some very rare conditions.
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Diluting with 1 to 10 parts water is common pharmaceutical practice if it’s not possible to get an adequate reading otherwise (for example water content <30% in a o/w emulsion); less water is always better. What I’m saying is that in most cases (high stearic acid products are one of the exceptions) the pH will not change enough to be of any cosmetically relevant concern.Regarding w/o emulsions: determining the ‘real’ pH of the inner phase may be close to impossible with standard means.
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Be consistent in your practice but be aware 1:10 dilution of your product is not your product.
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Just put your pH meter directly in the cream. The only reason to dilute is if you are dealing with a product that is a solid.
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Ok, thanks for the recommendation
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