Just wondering if anyone can provide any research articles or personal insights into whether any ingredients should be avoided when a formula has clays (kaolin and/or bentonite - ie for a clay mask).
We've been testing some clay mask formulas, and a small portion of people have had a reaction (red and burning).
I'm wondering if the clays are having a reaction with the preservative ingredients used? We don't get any reports of red/flushing or burning sensation when using the same preservatives in formulas that do not have the clays included. We're using a preservative mixture of Sodium benzoate 0.15%, potassium sorbate 0.1%, sodium dehydroacetate 0.15%, phenoxyethanol 0.3%. Also have EDTA 0.15%, Citric acid 0.15% Which is also present in the formulas without the clay and do not get reports of red/flush or burning. So only seem to get some reports of skin sensitivity when the clay is added.
I cant find any research to suggest anything.
Any suggestions or articles much appreciated.