Aluminum-Free Deodorant Formula discoloration

Formulating

Aluminum-Free Deodorant Formula discoloration

Posted by Picoboo on February 8, 2018 at 2:46 am

Hi there, I’ve made a batch of (roll on) deodorant using the following basic formula and while the first few batches were great I suddenly discovered that a batch turned various shades of pink/brown! I can’t figure out which element would possible turn the formula brown. I assumed it was the Sodium bicarbonate or magnesium, but my latest test batches seem to be stable. I’m wondering if the temperate of the water would do it? I can’t seem to get a repeat discolouration but i’m wary about this formula now. I would LOVE any help or suggestions. Thanks in advance. This is the formula:

Aqua 80%
Witch Hazel 5%
Sea Salt 5%
Bicarb Soda 5%
fragrance 1%
Xanthan Gum .5%
Aloe Vera .5%
Magnesium .5%
Preservative .5%

Picoboo replied 7 years, 2 months ago 4 Members · 8 Replies
8 Replies

belassi

Member
February 8, 2018 at 5:30 am

Magnesium .5%
I’m sure you don’t mean actual magnesium?
Picoboo

Member
February 8, 2018 at 6:11 pm

I mean the supplement. Wouldn’t want to kill anyone.
gld010

Member
February 8, 2018 at 6:48 pm

What preservative was it, specifically? I’ve seen cases on this forum of a certain preservative, I think one that was designed for the “natural” crowd, turning product pink. I think it was grapefruit seed extract or something related like an essential oil. Perhaps put a chelate compound in your formula? Or would putting a chelate compound not make sense if a metal salt, magnesium, is present on purpose?
gld010

Member
February 8, 2018 at 6:49 pm

Here are some threads about preservatives turning pink! Did you use one of these?

https://chemistscorner.com/cosmeticsciencetalk/discussion/comment/20155#Comment_20155

https://chemistscorner.com/cosmeticsciencetalk/discussion/comment/21957#Comment_21957
Picoboo

Member
February 8, 2018 at 8:48 pm

Thank you so much for your comments. I have used the Microcare DB brand of Dehydroacetic acid and benzyl alcohol. It IS the eco brand.
ozgirl

Member
February 8, 2018 at 11:12 pm

Benzyl alcohol and Dehydroacetic acid is designed to be used at pH values less than 6 and then still may be a little weak in protecting against mould.

I am guessing with all of that sodium bicarbonate your pH is above that level so your discolouration is most likely mould and/or bacteria.

Dehydroacetic acid is also known to discolour under some conditions.

Magnesium supplement can mean any number of magnesium salts (e.g. magnesium oxide, magnesium citrate, magnesium chloride, magnesium gluconate) some of which could also contribute to raising the pH of your product to levels that are not suitable for your preservative.
belassi

Member
February 9, 2018 at 2:45 am

^^^ what Ozgirl said. With 5% sodium bicarb - a base - and an acid?… isn’t that going to cause some kind of replacement reaction? My organic chemistry isn’t good enough to say.
It’s obvious your preservative is useless for this formula.
Picoboo

Member
February 10, 2018 at 7:12 am

Thanks Ozgirl and Belassi for all your help! I’ve decided to remove the bicarb (for starters) and I’m considering ditching the magnesium. I’ll also ask my supplier and for a nice strong preservative. As it turns out the fragrance in my formula is very high in Vanilla which will have also contributed to the discoloration. Thanks again!