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pH stability of zinc oxide as skin protector.
Can 1% zinc oxide function as skin protector when used at 1% @ pH 4-5 in emulsion?
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7 Replies
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What phase are you adding the zinc oxide to- water or oil? below pH 6 zinc oxide will start dissolving and you will have Zn ions in solution or new complexes which causes some formulation instability
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evchem2 said:What phase are you adding the zinc oxide to- water or oil? below pH 6 zinc oxide will start dissolving and you will have Zn ions in solution or new complexes which causes some formulation instabilityOff topic….as I am looking at Zn options (deo) ….. would this same aspect be true with Zinc Citrate? (Emulsified cream… with pH of 4.4.)
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I am not sure at this input (1%), but zinc oxide self regulates to pH of around 7 (in SPF or balms products)
I guess you get a slight skin protective benefits as it covers the skin a bit, but I would not rely on it.
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evchem2 said:What phase are you adding the zinc oxide to- water or oil? below pH 6 zinc oxide will start dissolving and you will have Zn ions in solution or new complexes which causes some formulation instability
I can use it in both phases. I just wanted that skin protection effect of it.
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Paprik said:I am not sure at this input (1%), but zinc oxide self regulates to pH of around 7 (in SPF or balms products)
I guess you get a slight skin protective benefits as it covers the skin a bit, but I would not rely on it.
Yes for SPF it should be around pH 7. But does it need to be at pH 7 for skin protection too?
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It has to be higher than 7 and a couple of buffers are needed.But why not just buy a bottle of calamine lotion？
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zetein said:It has to be higher than 7 and a couple of buffers are needed.But why not just buy a bottle of calamine lotion？
At what pH is calamine stable?
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