Tuesday, September 14, 2010

Deodorants: An aside...

It seems many of us are looking to make our own deodorants, and although it's not a difficult process to make them, it is hard to find a recipe you like. You'll see recipes for deodorants that look like lotion bars with some baking soda in them and recipes for making a clear gel stick into which you can add various essential oils and other destinkifying ingredients. I'm going to focus on the clear gel sticks as I don't like the feeling of a lotion bar under my arms - I find them far too greasy! But you could make them feel less greasy by including up to 5% IPP or IPM and some esters in place of the oils! (You really can't get away from the greasiness of the butter!)

A clear gel stick is generally made by using sodium stearate and a glycol. Sometimes you'll see glycerin, sometimes propylene glycol, and sometimes a combination of these humectants with alcohol as the base, but you'll almost always find sodium stearate or another sodium salt of a fatty acid.

Why sodium stearate? Sodium stearate is an anionic surfactant that is the sodium salt of a fatty acid, in this case stearic acid (C18:0). It is produced through the saponification process when a triglyceride comes in contact with sodium hydroxide (or lye), leaving us with 3 moles of sodium stearate and one mole of glycerin. And yes, it is considered a type of soap and is one of the main compounds we find in soap!

We buy it as a fine white powder and it's safe to use in leave-in products at up to 25%. It offers lubricity and thickening to the deodorant, and it's what makes it a clear gel stick type product. It also offers a little emulsification to the product, so we can add a fragrance oil at 1% to 2% without it eventually rising to the top of the stick. Sodium stearate is soluble in hot water or alcohol, so you'll want to melt it in either of these two liquids. Some recipes call for you to melt it on its own - you'll be there forever as the melting point is around 245˚C, and we simply can't reach those temperatures with our double boilers!

As an aside, you can use sodium stearate with sodium hydroxide as a kind of emulsification system. The sodium stearate goes into the oil portion, the sodium hydroxide in the water portion, and it creates a type of soap that will keep the lotion together. Unfortunately, the inclusion of anything with an electrolyte will destabilize the emulsion. So if you see sodium hydroxide in a lotion, look for sodium stearate to see if they've used this as an emulsifier! As a secondary note, this happens in our lotions all the time in little ways when we use stearic acid, and that's what causes the "soaping effect". 

So we know we need sodium stearate in our deodorant sticks. What else do we need?

I mentioned the humectant above. We need a polyol, which is an alcohol containing multiple hydroxyl groups. We can use glycerin or any of the glycols (propylene, di-propylene, hexylene, or butylene glycol) to create the clear stick with the sodium stearate. You can use alcohol as well, but you'll need to include one of these polyols with it. (The sticks with alcohol or witch hazel will offer a cooling effect, so there's a bonus to using those liquids.) Some deodorant sticks also contain water, generally to help melt the sodium stearate.

What else do we want to include? Well, you can pretty much any water soluble ingredient you want. I like to add proteins, aloe vera, and water soluble esters, like the PEG- or PPG esters. The esters offer slip and glide as well as detackification, which is a huge issue when you're using a humectant to make a deodorant. The last thing we want is something we have to drag along our sensitive underarm area every morning! You can include cyclomethicone to increase the slip and glide (generally around 3%) and you could include some botanical ingredients if you include a preservative. You can include things like cationic polymers to add a little moisturizing and to increase the mildness as well.

Interestingly enough, a lot of the deodorant recipes you see won't include a preservative. There are three reasons for this - the sodium stearate and polyol create a soap and soaps are supposed to be okay if unpreserved, and because a lot of recipes use Tinosan as the anti-bacterial component. (Tinosan is a preservative that doesn't play well with cationic ingredients, and we'll learn more about it in the next few days.) And products are supposed to be self-preserving if you use 60% or more alcohol. I like to include a preservative anyway, especially if I'm using a hydrolyzed protein or botanical ingredient.

Join me tomorrow for fun formulating a deodorant stick! 


Petra said...

I've been waiting for this!!!
I made a test batch of the recipe with sodium stearate that you sent me a while ago (#22) and I like the way it feels. It feels like a good starting point, so I look forward to "playing" along in the coming days.

I was curious about the need for a humectant. Seems kind of counter to what you would want happening under your arms.

TheSoapGallery said...

OH Wow! Thank you for starting a series on deodorants! I always get so much from your blogs :)

Susan Barclay-Nichols said...

Hi Petra. The humectant isn't for attracting water; it's what will make the sodium stearate into a soap to make the clear gel stick. Did you notice tomorrow's recipe is the one I sent you. I quite like it, but there's one more I really like coming up!

Hi TheSoapGallery. I've always wanted to play with deodorants, so here's my chance!

Meg UK said...


Thank you for this wonderful post. I'm hoping to try this myself as I'm trying to make a Lush's Aromaco-type deodorant myself and this is a perfect starting place for that.

I was just wondering whether you think magnesium stearate might work here instead of sodium stearate? I'm really not sure chemistry-wise whether it would. Unfortunately it seems pretty much impossible for the home crafter to get hold of sodium stearate here in the UK (and the French supplier I normally use doesn't stock it either). I've got some stearic acid but really don't want to have to go through the whole Stearic Acid/Sodium Hydroxide reaction thing just to get the sodium stearate required for the deodorant. I've also checked out some pure soaps on sale but they seem to be some combination of sodium stearate, sodium cocoate, sodium palmate and/or sodium palm kernelate. Fingers crossed there might be an alternative you can suggest. Thanks again.

Robert Williams said...

Great blog post!

Sânziene şi Mătrăgună said...

hi Susan!

saponifying stearic acid with NaOH will result in sodium stearate?

I have no supplier for sodium stearate, but .. I may consider making the salt if I got this right ; )

Sânziene şi Mătrăgună said...

oh, sh*t- why did I not just search before asking?


"Purified sodium stearate can be made by neutralizing stearic acid with sodium hydroxide."

here I come, home made deodorant gels!!!!! :-)

Ina said...

Synthesizing sodium stearate is NOT all it's cracked up to be! Just for anyone thinking about trying to soap it. Just saying. Not that I've been fighting with it for the last hour or so or anything.

Srjnm said...

Hi Susan,
I recently found your blog and I can't stop reading! You have been a fabulous resource and have encouraged me to experiment on new products. Thank you for your time, sharing your knowledge, and your research!

And now for my question.... :) One of the comments indicated that sodium stearate can be made by neutralizing stearic acid with sodium hydroxide. I have not been able to find a reliable source on how to do that....the process and the formula.

Can you help?

I apologize in advance if you have written about this already and I just couldn't find it. Thank you so much!! - Rodeth

Susan Barclay-Nichols said...

HI Srjnm! I'm afraid I don't know how to make sodium stearate. There are some French speaking blogs that show how to go through this process...

Erin Foster said...

Hello Susan,
Thank you for your blog; your information is so helpful! I'm trying to source sodium stearate and I am not having any luck, like everyone else. Is there something that could be used as a substitute?

Daisy said...

Hi! I have learned so much from your blog, I was hoping you might be able to help me with something... I'm trying to create a deodorant for very sensitive skin. I'm planning to use:

7% beeswax
25% cocoa butter
25% hempseed oil
10% cyclomethicone
5% IPM
1.5% tea tree oil
1.5% fragrant oil
25% Dry-Flo

I know these are all oil-based ingredients, but I hope the cyclomethisone and IPM will stop it from feeling greasy.

Is there anything I've missed? Anything which will definitely not work?

Susan Barclay-Nichols said...

Hi Daisy. What you're making is a lotion bar with essential oils. I don't recommend using that amount of fragrance or essential oils in something that'll be on your skin all day. A few thoughts... Why are you using such a low amount of beeswax? This is going to be a very soft bar with so little wax. Have you tried this? Did it work? Why so much Dry-Flo? Why include it and why so much? Are you going to be able to handle having all that greasiness under your arms all day? It might be less greasy feeling, but it won't be non-greasy.

Just a few thoughts to spur some creativity! Let us know how this turns out!

Daisy said...

That was fast!

I wanted to use as much tea tree oil as possible because it seems to be the only antimicrobial agent in the recipe (and the only thing which will stop me getting stinky). I can't use any kind of alcohol because it gives me contact dermatitis (same with aluminium or alum salts).

I've tried a couple of haphazard recipes with a greater concentration of beeswax, and they feel very waxy, even more than what I'd be comfortable with in a body butter - very dense and oily. I was hoping I wouldn't have to add quite so much beeswax if I was using cocoa butter (rather than something like coconut oil). I know the recipe is all oils, but with the exception of cyclomethisone, I'm only adding things I know I won't be allergic to.

I included Dry-Flo because it seems to thicken the mixture really well. I want to make something resembling a stick deodorant, rather than a cream.

And you're right, the greasiness is my main concern. I know I should try one of the recipes you've already posted, but I've never made an emulsion before, and I'm too scared to get it thoroughly wrong.

Kim said...

Can sorbitol be used as the polyol for this gel deodorant- will the recipe work? What is the feel of this deodorant like- is it glidy or is it dry feeling?

Susan Barclay-Nichols said...

Hi Kim. I don't know. Make a small batch and see what you think! I used glycerin and it was a terrible choice, so it's only through experience whether you know or not if it'll work in practice. The ones I made were like solid clear sticks, and they were glidy. I didn't think they were greasy or dry feeling. They felt like the clear sticks I've bought in the past.

It sounds like you'll get all your answers through a small experiment! I really hope you return and share your thoughts.