Maya, bentonite, laponite or good old Veegum (magnesium aluminum silicate) would solve your stability issue, even with the oils incorporated. Clays tend to deactivate formaldehyde donor preservatives, (and others I suspect), especially when added after incorporation. Always add your preservative first to the water, before adding the clays and colloids. Perhaps someone else in the Forum knows the best preservative to use with clays. I have to believe simpler molecules like benzyl alcohol, sodium benzoate, sodium dehydroacetate would do well; PCMX would be a slam-dunk.
I think sometimes we forget to start from the beginning.
What is the purpose that consumers use a clay mask for?
What benefit does adding oil to a water-based clay product deliver? Are you able to add enough oil to a clay mask to overcome the oil-absorbing properties of the clay?
Why would you expect that adding oil to a water and clay mixture without using emulsifiers would result in a stable product?
Is your finished product passing micro? If not, which of your raw materials is contaminated?
April 6, 2014 at 9:41 pm
Bobzchemist, these are very good questions. The formulas are provided by our supplier, and it looks like other customers have already tried them. Probably they used the products right away, so stability wasn’t an issue…
Since mold grew on a couple of the products, those masks definitely wouldn’t pass micro. I don’t think that oils were contaminated (low water activity). We used the same source of water for all the products, and with only 2 of them we had a problem. So, if I see it correctly, the source of contamination is clay. I don’t expect raw materials to be sterile, and if I want to store those masks for a while (and not in the fridge), I guess we will have to use preservatives… That’s very weird that the supplier doesn’t include them in the recipe.
@chemicalmatt I’m having stability issues with my clay mask and after comparing samples before and after adding preservative, I can definitely say it’s the preservative that is causing it.
My mask is actually an emulsion (I’m also against the idea of having oils in the mask, but that’s what our customer wanted) with kaolin and MgAl Silicate. I’m adding phenoxyethanol at the end of the process.
Is there a reason why adding it at the beginning would make a difference- more stable?