Friday, April 9, 2010

Surfactants: Alkyl ether sulfates

Alkyl ether sulfates result from the sulfation of an ethoxylated fatty alcohol. Ethoxylation is the process by which ethylene oxide is added to a fatty acid alcohol to create detergent properties in a surfactant.

If you compare the molecule above to that of SLS (from yesterday), you'll see that little oxygen (O) atom is messing up the clean squiggliness of the carbon chain. That's the ether part of the process. (Ethers are a type of organic molecule that contains an oxygen joining two alkyl groups. You can see how the oxygen is in the middle, implying it is connecting stuff.)

Alkyl ether sulfates - like sodium laureth sulfate (SLeS) - have good foam stability in hard water, good skin tolerance (less irritation), and are easily thickened by salt, Crothix, or glycol distearate. They are also thickened by adding cocamidopropyl betaine. It is considered a mild cleanser (definitely milder than SLS!).

You can find SLeS in two forms - SLeS 2 EO (or SLeS 2 mole) and SLeS 3 EO (or SLeS 3 mole). This EO part is about the ethoxylation of the surfactant. The higher the ethoxylation, the less irritating it will be for your skin or eyes and the more soluble in water.

You'll also find different concentrations of the amount of SLeS in your bottle. I use Stepan Steol CS-230 (click here for the data bulletin sheet for Steol CS-230), which contains 26% active SLeS and is a 2 mole version. It has a pH of 6 to 7.5 and a freezing point of -2˚C.

For SLeS, we find mild to moderate skin irritation at 10% active. So if you used 40% SLeS in your body wash, you'd get 10.4% active SLeS in your product, which could cause some mild skin irritation. You wouldn't want to use that much of one surfactant in any product, so it's safe to say that this is a less irritating surfactant than SLS and on par with most of the others we'll be investigating!

We're also seeing ammonium laureth sulfate gaining in popularity. It has all the qualities of SLeS - good foaming and stability in hard water, better skin tolerance, good thickening with salts - with a little more mildness. It is considered a gentle to mild cleanser. Stepan's Steol CA-230 is 25% active with 15% required for mild to moderate skin irritation, which means you need to use 60% before you get that to that amount! It has a pH of 6.5.

Either of these surfactants would be suitable for most, if not all, skin types. The more sensitive skin types might prefer ALeS over SLeS because of its increased mildness.

I enjoy using both SLeS and ALeS in my creations, so here are a few ideas for formulating with alkyl ether sulfates!

Join me tomorrow for more fun with the sulfates!


persian girl said...

Hi Susan, I wanted to buy some ALES and SLES to make some shampoos but I don't know where to buy from. Like you I'm also from Canada, expect the east coast. :) Thanks!

Anonymous said...

This is the dumbest thing ever. Why use man made chemicals to strip the essential oils off your skin and hair? Coconut oil is a natural surfactant and so good for you whereas als sles and SLS are not! SLS and SLeS are derived from coconut oil but so chemically altered that's it provides no benefits. Look into making any of your soaps using Dr. Bronner's Castile Soap if you want a natural cleansing shampoo or body wash that you can make yourself that's good for your hair and skin, provides a good lather all without stripping essential oils your body produces for your skin/hair. You want to promote skin aging, stripping those oils is a quick way to do it. Try that Dr. Bronners soap for a soap base, fill most of the bottle with Aloe Vera Juice (so beneficial), and add some oils to help promote skin health.

Susan Barclay-Nichols said...

Thank you so much for your opinion, Ryan. I'm sure you can find blogs that cater to your point of view as mine clearly doesn't. If you're interested in learning more about cold process soap and its effect on your hair, check out the hair care section of the blog.

devits35 said...

Ryan, you look silly. all of what you said makes no sense. how can raw coconut oil be a surfactant? all your doing is adding oil to a product that already has a surfactant in it and whats worse is your using castille soap in your hair! wow so many errors in your post.

equine66 said...

Susan thank you for sharing ur know how. I am a novice at this I'm just wondering regarding ur formulation in regards to the body soap which has honey Quat n SLeS (one is cationic the other anionic) I am under the impression these two species cannot mix pls share ur insights regarding this perplexing situation. Tq Gautam Dutta.

Susan Barclay-Nichols said...

Hi Gautum! Check out this post on honeyquat for more information. It is suitable for mixing in surfactant systems.