want to make a sunscreen lotion without other actives than the UV filters, for
own use. The SPF will be about 15. The UV filters I use are micron. zinc- and
titanium(di)oxide, coated with simethicone (SofiTix).
I also want to add another, volatile silicone, because of its nice skinfeel. I know silicones can be tricky, so I hope the stability of the way I formulated etc will be sufficient. This is the first time I will be working with silicones.
My formula, feel free to comment, much appreciated!
· q.s. deionized water
· 8% E-wax (glyceryl stearate + PEG100 stearate)
· 2% cetyl alcohol
· 1% cyclopentasiloxane
· 9% sunflower seed oil
· 1% petrolatum
· 1.5% glycerin
· 0.5% α-tocopherol
· 6% SofiTix (nano zincoxide/nano titaniumdioxide/simethicone)
· 0.4% phenoxyethanol
· 0.3% benzyl alcohol + DHA (Cosgard)
· 0.1% potassium sorbate
· citric acid in aqua for pH < 5.5
Disperse SofiTix in mixture of sunflower oil + cyclo D5
Water + glycerin, heat to 70C
Melt the emulsifiers + petrolatum -> 70C
phase 1 to the 2+3 emulsion in the cooling phase.
Add preservatives + α-tocopherol.
QUERY: Would 9% oil be enough to disperse 6% SofiTix?
If so, should I use even less oil in the premix and add oil to phase 3?
Would this be stable enough for the 1% cycloD5 and the simethicone coating?
I wanted to add benzyl alcohol to prevent discoloration by potassium sorbate, like @DRBOB@VERDIENT.BIZ said. I don’t use it very long, so it probably won’t be necessary.
Is pH 5.5 low enough for potassium sorbate to ‘metabolize’ into sorbic acid?
Thanks a bunch!
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