# do I need a preservative in my zinc oxide deodorant??



## BodyOdorProblem (Jul 19, 2014)

Hi guys,

I have a problem with my deodorant which is that whenever I start sweating the zinc oxide in my roll on deodorant goes rancid on my skin. I don't know why that is and am wondering is it because I need to add a preservative??

the recipe is:
10g zinc oxide
40ml lemon juice
tea tree oil (10 drops)
sandalwood fragrant oil (10-20 drops)

why does the zinc oxide go rancid on my skin I don't understand this???


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## CanaDawn (Jul 19, 2014)

Are you using zinc oxide mixed in some kind of base cream or as pure powder?
I don't understand how zinc oxide can go rancid.


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## new12soap (Jul 19, 2014)

I don't think it's the zinc oxide, I think it's the lemon juice that is the problem. You can't really mix water soluble ingredients with oils without a preservative but even then I wouldn't recommend food unless you are going to both use a preservative and keep it refrigerated.


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## CanaDawn (Jul 19, 2014)

or...do you mean it shows up in little clumps?  (I'm not really understanding)


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## Susie (Jul 19, 2014)

OK, completely re-writing this after re-reading the OP.

Let's start with the _*cause*_ of odor in the underarms:  
You have bacteria all over your skin at all times.  Most of this bacteria is completely harmless.  The bacteria particularly love dark, moist areas.  Like your armpits.  So, lots of happy bacteria are reproducing there to make more happy bacteria.  

Then you sweat.  You sweat more in places where skin meets skin as you have 2 sets of sweat glands involved.  Sweat alone does not have a bad smell.   However, you mix that sweat with the bacteria, and it starts killing off that bacteria, and then you have smell.  More bacteria + more sweat = more smell.

To stop having this problem, you have several things you can try before going to see a doctor.  But, honestly, I would start by going to a doctor, so you can get all the potential underlying causes ruled out, as some of them can be quite serious and require medical treatment.

First, you can try reducing the bacterial load of the skin.  This means using an antibacterial soap/cleanser of some sort.  There are a couple of excellent ones your doctor can prescribe.  If you must try something at home before going to the doctor, then you can look up over the counter options on the internet.  I would NOT try to use these on all of your body, nor is it an "every day, forever" type solution.  This is a short term solution at best.  If you have an objection to using antibacterial soaps/cleansers, then you are going to be washing several times a day.(with less than stellar results)

Second, you can try sweating less.  Using an antiperspirant, not just a deodorant.  And the formerly prescription-only strengths are now available over the counter.  There are also other products an MD can prescribe or recommend that I just do not feel comfortable discussing in a forum.  That would be stepping over the "practicing medicine without a license" line.

As to your original question.  It is not the zinc oxide going rancid.  It is most likely the lemon juice spoiling.  If you keep this for more than 3 days at room temperature, or 7 days in the refrigerator, then that is exactly the problem.  I would never use lemon juice in anything I needed to store.  You might want to think about adding the other ingredients to a lotion multibase that already has preservative, and perhaps using citric acid to drop the pH.


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