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Q for Dr. T re: ZnO

 
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dven



Joined: 17 Nov 2007
Posts: 8

PostPosted: Sun Jan 06, 2008 5:17 pm    Post subject: Q for Dr. T re: ZnO Reply with quote

Mixed a new cream w/actives DMAE, Glycolic Acid (8%) + 600 mg of ZnO (for an SPF of about 20) Total cream is about 2 oz. I thought the DMAE and AHA would balance the ph but the stuff burns (tested on forearm). What do you think is going on? Is the ZnO giving me the burn? Thanks for any help.
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drtodorov
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Joined: 10 Dec 2004
Posts: 3255

PostPosted: Sun Jan 06, 2008 5:26 pm    Post subject: Reply with quote

Could be a number of things. What is the pH of your cream? (you can measure with a pH strip). What is the exact form and concentration of DMAE you used? Keep in mind that acids increase the solubility of Zn0, so it stops being inert.

Overall, I do not (and never did) recommend this kind of experimentation unless you are an expert. There are too many factors too take into account.
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dven



Joined: 17 Nov 2007
Posts: 8

PostPosted: Sun Jan 06, 2008 6:18 pm    Post subject: Thanks for the info Reply with quote

I used 500 mg of DMAE (from 1.5g DMAE bit) Remember, it's 2 oz of cream, so nothing excessive. My base, besides being crappily thin, is aloe and udder cream (2:1 ratio). I have tried glycerin, KY and Curel and they all leave me sticky. (I have the DIY info pack.)

Is the fact that I'm experimenting w/ ZnO reason for concern, or the glycolic acid? (My doc recommended Neostrata for my skin and when I realized it's basically just glycolic acid, I wanted to try and make something myself....)

And I read that any AHAs w/o sun protection is a bad idea. Hence, the ZnO.

Testing with a ph strip is an excellent idea. Thanks.

With this new info, any thoughts, Dr. T?
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drtodorov
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Joined: 10 Dec 2004
Posts: 3255

PostPosted: Sun Jan 06, 2008 9:27 pm    Post subject: Reply with quote

If you used DMAE bitartrate or another DMAE salt -- those are pH neutral and won't fully neutralize glycolic acid that you added. As a result, you have DMAE, and Zinc Oxide in acidic environment. This is not their typical use in skin care and their side effects under these atypical conditions are not known -- except we do know that zinc oxide definitely becomes far more soluble and less inert in acidic environment.

I think mixing either DMAE bitartrate or zinc oxide with acid is NOT a good idea w/o serious research and testing, which is not a DIY proposition.
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dven



Joined: 17 Nov 2007
Posts: 8

PostPosted: Tue Jan 08, 2008 8:36 am    Post subject: Thanks Reply with quote

Thanks for the advice and concern, Dr. T. Think I'll hold off with this latest batch...
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