Tuesday, July 16, 2013

Newbie Tuesday: What are surfactants?

Let's start this series on surfactants! You'll want to bookmark the surfactants section of the blog and download the comparison charts. I encourage you to follow the links on this page as I've written quite a lot on surfactants and these are summaries of those posts.

What are surfactants? First, a definition (from Wikipedia): Surfactants are wetting agents that lower the surface tension of a liquid, allowing easier spreading, and lower the interfacial tension between two liquids. (In other words, a surfactant makes it possible to mix oil and water or for lathery things to remove oil or dirt from your skin or clothes.)

Surfactants have a hydrophilic (or water-loving) head and a lipophilic (or fat-loving) tail. The hydrophilic head clings onto watery stuff - say the water phase of our lotion - and the lipophilic tail creates a ball around the oily stuff - the oil phase of our lotion.

For the purposes of these posts, my focus will be the lathery, foamy types of surfactants or surfactants that exhibit detergency - meaning something that wets and solubilizes oils, soils, and proteins, and removes them from surfaces, clothes, and people. They tend to be bubbly, foamy, and lathery.

Basic, general informationAll detergents will irritate our skin, no matter how mild they are. (Yes, even cold process soap because the very nature of putting a detergent-y surfactant of our skin means we are removing oils, and our skin doesn't like that! Heck, even water can irritate some skin types!) Our goal is to find surfactants that are less irritating to our skin or scalp and include ingredients in our products that will increase mildness.

Every liquid surfactant contains water, which means it will contain - at the very least - the surfactant, water, and preservative. If you read a data bulletin or a suppliers' write up on a surfactant, it should tell you the active amount of surfactant in the bottle.

For instance, if you click on this data bulletin for Bioterge AS-40 (C14-16 olefin sulfonate), you can see that it contains 39.1% active ingredients. If the safe as used rate for this surfactant is "safe as used" for rinse off products, meaning you could make a product with 100% this ingredient and be safe. The eye and skin irritation level is at 10% active ingredient - meaning you have 10% in your rinse off product. If you use 25% in your product, you would have less than 10% (25 grams of product x 0.38 = 9.75 grams of active C14-16 olefin sulfonate).

As a note, the reason this surfactant could irritate your eyes or skin is because it's alkaline with a pH of 8.5. Our eyes are pH 7.2, meaning something that isn't around that neutral pH is going to bother them. Our skin has a pH of 4.5 to 5.5 or so, meaning it's acidic. This doesn't mean the surfactant is harsh or bad for us, it means that our skin and eyes like things that match their pH levels. 

If you're interested in knowing the "safe as used" rates for various ingredients, click here!

It's safe to assume that most - if not all - are considered mild cleansers when it comes to personal care products. I'll be using a scale that's a little annoying - sorry, but they all want to be considered "mild cleansers", so we need to re-define the word! Think of it on a scale from 1 to 3 (but I hate using numbers, so you won't see "1" or "3" in my posts!)
  • Gentle or very mild - this surfactant is unlikely to cause skin irritation when used at the suggested amount or lower. It is unlikely to bother your eyes as well.
  • Mild - this surfactant is unlikely to cause skin irritation when used at the suggested amount or lower, but don't get it in your eyes. It could cause irritation for people with very sensitive skin.
  • Not so mild - this surfactant may cause mild skin irritation when used at the suggested amount or lower, and it may cause eye irritation. It could cause irritation for people with sensitive to normal skin. The only one that falls definitely in this category is SLS.
Part of what we'll be doing in this Newbie Tuesday series is figuring out which surfactants work best for you - your skin or hair type, your skin sensitivity, your formulating level, your philosophy about formulating, and so on. This is where the surfactants section of the blog comes in handy! You will want to get those charts and keep them handy!

How to interpret surfactant names? One of the things I see a lot is the idea of something being bad for you because it has a long name you can't understand. Here's your chance to learn what those names mean! (Again, check out the longer version of this post for more information.)

Name: Sodium C14-16 Olefin Sulfonate
The sodium is the cationic or positively charged ion.
The C14-C16 indicates the type of fatty acid used in the surfactant (C14 - myristic, c16 - stearic).
The olefin indicates it is a straight chain organic molecule (click here if you are dying to learn more!) It is an unsaturated alkene, a straight chain with at least one double bond. (You might remember the whole unsaturated-double bond thing from the oils and butters.)
The sulfonate part indicates it was created through a process of sulfonation, but the sulfur is directly linked to a carbon molecule.

C14-16 olefin sulfonate could be derived from coconuts or shea butter or anything else that contains C14 and C16 fatty acids.

Your homework for next week is to take a look at the long forms of these summarized posts, and download and take a look at the charts. I really want you to visit your favourite supplier and see what surfactants they carry because there's no point in falling in love with using SCI if you can't get it in your part of the world!

See you next week when we take a look at a few surfactants in depth. 

1 comment:

Ren Simonitis said...

Thank you so much for all the great information you're sharing! It's helpful to me in my endeavors to use essential oils safely and share safety with others!